Breast Cancer Screening: When Should I Start Having Mammograms?

You may want to have a say in this decision, or you may simply want to follow your doctor's recommendation. Either way, this information will help you understand what your choices are so that you can talk to your doctor about them.

Breast Cancer Screening: When Should I Start Having Mammograms?

Get the facts

Your options

  • Start having screening mammograms at age 40 (or anytime in your 40s).
  • Start having screening mammograms at age 50.

This information is for women who are choosing to have screening mammograms and who are at average risk for breast cancer. It is not for women who are at high risk. If you don't already know your breast cancer risk, you can ask your doctor. Or you can look it up at www.cancer.gov/bcrisktool/.

Key points to remember

  • Mammograms can find some breast cancers early, when the cancer may be more easily treated. Studies show that a small number of women who have mammograms may be less likely to die from breast cancer.
  • The risk for breast cancer goes up as you get older. In general, women younger than 50 are at a lower risk for breast cancer. Because of this, women ages 50 to 70 are more likely to benefit from having mammograms than women who are in their 40s.
  • Mammograms may miss some breast cancers. And some cancers that are found may still be fatal, even with treatment.
  • Mammograms may show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.
  • Mammograms may find cancers that will never cause a problem (called overdiagnosis). Some breast cancers never grow or spread and are harmless. You might have this type of cancer, but a mammogram can't tell whether it's harmless. So you may get cancer treatment—including surgery, radiation, or chemotherapy—that you don't need.
  • If you have health problems that would make it too hard to go through cancer treatment, or if you would not want to have treatment, there may not be a good reason to have a mammogram.
FAQs

What is a mammogram?

A mammogram is an X-ray of the breast that is used to screen for and diagnose breast cancer.

There are two types of mammograms.

  • A screening mammogram looks for signs of breast cancer before any symptoms appear.
  • A diagnostic mammogram looks for breast cancer in women who have symptoms. Or it is done if you had an abnormal screening mammogram. It's also used to find an area of suspicious breast tissue to remove for a biopsy.

This decision aid is about screening mammograms.

What are the benefits of having a mammogram?

Mammograms can find some breast cancers early, when the cancer may be more easily treated. Often a mammogram can find cancers that are too small for you or your doctor to feel.

Studies show that a small number of women who have mammograms may be less likely to die from breast cancer.

The risk for breast cancer goes up as you get older. In general, women younger than 50 are at a lower risk for breast cancer. Because of this, women ages 50 to 70 are more likely to benefit from having a mammogram than women who are in their 40s.

What are the risks of having a mammogram?

Each time you have a mammogram, there is a risk that the test:

  • May miss some breast cancers. And some cancers that are found may still be fatal, even with treatment.
  • May show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.
  • May find cancers that will never cause a problem (called overdiagnosis). Some breast cancers never grow or spread and are harmless. You might have this type of cancer, but a mammogram can't tell whether it's harmless. So you may get cancer treatment—including surgery, radiation, or chemotherapy—that you don't need.
  • Will briefly expose you to very small amounts of radiation. While the risk from being exposed to radiation from a mammogram is low, it can add up over time.

What do the numbers tell us about the benefits and risks of having a mammogram?

Benefits

Breast cancers found in women having annual mammograms over 10 years*footnote 1
Ages 40–49 About 19 out of 1,000 women
Ages 50–59 About 30 out of 1,000 women
Ages 60–69 About 44 out of 1,000 women

*Based on the best available evidence (evidence quality: moderate to high)

Breast cancer deaths over 10 years with or without annual mammograms*footnote 1
Women who have mammograms Women who don't have mammograms Mammograms making a life-saving difference
Ages 40–49 About 3 out of 1,000 will die of breast cancer Between 3 and 4 out of 1,000 will die of breast cancer For less than 1 out of 1,000 women
Ages 50–59 About 6 out of 1,000 will die of breast cancer About 7 out of 1,000 will die of breast cancer For about 1 out of 1,000 women
Ages 60–69 About 9 out of 1,000 will die of breast cancer About 13 out of 1,000 will die of breast cancer For about 4 out of 1,000 women

*Based on the best available evidence (evidence quality: moderate to high)

Breast cancer diagnosis

Mammograms can find some breast cancers early, when the cancer may be more easily treated. Often a mammogram can find cancers that are too small for you or your doctor to feel.

Take a group of women who have a mammogram every year for 10 years .footnote 1

  • About 19 out of 1,000 women ages 40 to 49 will be diagnosed with breast cancer. This means that about 981 won't.
  • About 30 out of 1,000 women ages 50 to 59 will be diagnosed with breast cancer. This means that about 970 won't.
  • About 44 out of 1,000 women ages 60 to 69 will be diagnosed with breast cancer. This means that about 956 won't.

Survival

Studies show that a small number of women who have mammograms may be less likely to die from breast cancer. Since the risk for breast cancer goes up as you get older, women ages 50 to 70 are more likely to benefit from having a mammogram than women who are in their 40s.

Take a group of women who have a mammogram every year for 10 years .footnote 1

  • Mammograms will make a life-saving difference for less than 1 out of 1,000 women ages 40 to 49. This means that for more than 999 of them, having mammograms won't make a difference.
  • Mammograms will make a life-saving difference for about 1 out of 1,000 women ages 50 to 59. This means that for about 999 of them, having mammograms won't make a difference.
  • Mammograms will make a life-saving difference for about 4 out of 1,000 women ages 60 to 69. This means that for about 996 of them, having mammograms won't make a difference.

The numbers in the tables and narratives include women who are expected to be diagnosed with invasive breast cancer or an early form of noninvasive breast cancer called ductal carcinoma in situ.

Risks

False-positive test results and unnecessary biopsies with annual mammograms over 10 years*footnote 1
Number of women who will have at least one false-positive that results in more testing (but turns out not to be cancer) Number of women who will have a biopsy they don't need
Ages 40–49 About 613 out of 1,000 women About 70 out of 1,000 women
Ages 50–59 About 613 out of 1,000 women About 94 out of 1,000 women
Ages 60–69 About 497 out of 1,000 women About 98 out of 1,000 women

*Based on the best available evidence (evidence quality: moderate to high)

Mammograms may show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.

Take a group of women who have a mammogram every year for 10 years .footnote 1

  • About 613 out of 1,000 women ages 40 to 49 will have at least one false-positive test result. This means that about 387 won't.
  • About 613 out of 1,000 women ages 50 to 59 will have at least one false-positive test result. This means that about 387 won't.
  • About 497 out of 1,000 women ages 60 to 69 will have at least one false-positive test result. This means that about 503 won't.

Breast cancer screening can also lead to unnecessary biopsies.

Take a group of women who have a mammogram every year for 10 years .footnote 1

  • About 70 out of 1,000 women ages 40 to 49 will have a biopsy they don't need. This means that about 930 won't.
  • About 94 out of 1,000 women ages 50 to 59 will have a biopsy they don't need. This means that about 906 won't.
  • About 98 out of 1,000 women ages 60 to 69 will have a biopsy they don't need. This means that about 902 won't.

Mammograms may find cancers that would never have caused a problem if they had not been found through screening (called overdiagnosis). But a mammogram can't tell whether the cancer is harmless. So you may get cancer treatment that you don't need.

Out of 1,000 women who are diagnosed with breast cancer during screening mammograms, experts estimate that about 190 of them may get treatment they don't need.footnote 1

The numbers in the tables and narratives include women who are expected to be diagnosed with invasive breast cancer or an early form of noninvasive breast cancer called ductal carcinoma in situ.

Understanding the evidence

Some evidence is better than other evidence. Evidence comes from studies that look at how well treatments and tests work and how safe they are. For many reasons, some studies are more reliable than others. The better the evidence is—the higher its quality—the more we can trust it. The information shown here is based on the best available evidence.footnote 1 The evidence is rated using four quality levels: high, moderate, borderline, and inconclusive.

Another thing to understand is that the evidence can't predict what's going to happen in your case. When evidence tells us that 2 out of 100 people who have a certain test or treatment may have a certain result and that 98 out of 100 may not, there's no way to know if you will be one of the 2 or one of the 98.

When do experts advise starting mammograms?

For women who are at average risk for breast cancer, there are no easy answers for when to start having mammograms. Even the experts don't agree on when is the best time to start.

For example:

  • The U.S. Preventive Services Task Force recommends that most women begin screening at age 50, and then have a mammogram every 2 years. The Task Force recommends that women in their 40s be offered screening and allowed to make an informed choice.
  • The American Cancer Society recommends that most women begin screening at age 40, and then have a mammogram every year.

But most experts do agree that all women should be informed about the risks and benefits of mammograms and offered screening by age 50.

When to stop having mammograms is another decision. You and your doctor will decide on the right age to stop screening based on your personal preferences and overall heath.

Compare your options

Compare

What is usually involved?









What are the benefits?









What are the risks and side effects?









Start mammograms at age 40 Start mammograms at age 40
  • At age 40:
    • You go to your doctor if you notice any changes in your breasts.
    • You may get a mammogram every 1 to 2 years, depending on what you and your doctor decide.
    • If you have an abnormal test result, you may have more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer.
  • Mammograms can find some breast cancers early, when the cancer may be more easily treated.
  • Studies show that a small number of women who have mammograms may be less likely to die from breast cancer.
  • Earlier screening may help you find breast cancer sooner.
  • Each time you have a mammogram, there is a risk that the test may:
    • Miss some breast cancers. And some cancers that are found may still be fatal, even with treatment.
    • Show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.
    • Find cancers that will never cause a problem (called overdiagnosis). You might have this type of cancer, but a mammogram can't tell whether it's harmless. So you may get cancer treatment—including surgery, radiation, or chemotherapy—that you don't need.
  • By starting mammograms earlier, you increase your chances of getting a false-positive test.
  • By starting mammograms earlier, you increase your chances of finding a cancer that may never cause a problem.
  • You are briefly exposed to very small amounts of radiation each time you have a mammogram.
Start mammograms at age 50 Start mammograms at age 50
  • Until age 50:
    • You go to your doctor if you notice any changes in your breasts.
  • At age 50, you start getting mammograms. You may get one every 1 to 2 years, depending on what you and your doctor decide.
    • If you have an abnormal test result, you may have more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer.
  • Mammograms can find some breast cancers early, when the cancer may be more easily treated.
  • Studies show that a small number of women who have mammograms may be less likely to die from breast cancer.
  • Since the risk for breast cancer goes up as you get older, women ages 50 to 70 are more likely to benefit from having a mammogram than women who are in their 40s.
  • By waiting until age 50 to start having mammograms:
    • You avoid the cost and inconvenience of getting a mammogram during your 40s.
    • You limit the number of mammograms that may result in a false-positive test.
    • You limit the number of mammograms that may find a cancer that may never cause a problem.
    • You limit your exposure to radiation.
  • Each time you have a mammogram, there is a risk that the test may:
    • Miss some breast cancers. And some cancers that are found may still be fatal, even with treatment.
    • Show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.
    • Find cancers that will never cause a problem (called overdiagnosis). You might have this type of cancer, but a mammogram can't tell whether it's harmless. So you may get cancer treatment—including surgery, radiation, or chemotherapy—that you don't need.
  • You are briefly exposed to very small amounts of radiation each time you have a mammogram.
  • There is a small risk that a cancer that develops before age 50 may not be found early. You could miss the chance to start treatment early when it has a higher chance of success.

Personal stories about when to start having mammograms

These stories are based on information gathered from health professionals and consumers. They may be helpful as you make important health decisions.

No one in my family has ever had breast cancer. So I'm not at high risk for getting it. I talked with my doctor about this, and I read all of the information I could. My doctor says it's my decision, but she is here to answer any questions and talk it over. I'm worried about false positives. I have a friend who has had two biopsies, and many sleepless nights, and it turned out to be nothing. I'm having a tough time deciding. I think for me the best decision is no decision. I'll keep reading and thinking about it. I'm okay with this.

Keiko, 41

I'm not really worried about getting breast cancer, so I've decided to wait until I'm 50 to start having mammograms. I just turned 40, and I've always been healthy and active. Plus, I don't have any extra risk factors. In the meantime, I'm going to mention any changes I notice in my breasts to my doctor.

Helen, 40

My friend was diagnosed with late-stage breast cancer after finding a lump in her breast when she was 48. She didn't have any risk factors for the disease, so she hadn't had any mammograms before then. I can't help but think that maybe if she'd had a mammogram a year or two before, the cancer may have been found earlier. I'm not at high risk for breast cancer either, but I'm going to keep having my yearly mammogram just to be sure nothing is wrong.

Sally, 46

I travel a lot for my job, and my days are often crammed with back-to-back meetings, so trying to schedule a mammogram is a challenge. But I've managed to do it, and all my mammograms have been normal. Now some doctors are saying that it's okay for women to wait and start having mammograms at 50. I think that's reasonable, and I don't feel like I would be putting myself at much greater risk for missing a cancer by waiting until I'm 50 to get my next one.

Bella, 44

What matters most to you?

Your personal feelings are just as important as the medical facts. Think about what matters most to you in this decision, and show how you feel about the following statements.

Reasons to start mammograms at age 40 (or anytime in your 40s)

Reasons to start mammograms at age 50

I'm worried that I might get breast cancer at an earlier age.

I'm not too worried that I might get breast cancer at an earlier age.

More important
Equally important
More important

I think starting mammograms earlier is worth the increased risk of having a false-positive test result if it could find cancer early.

I think the chance of having a false-positive test result is more likely than the test finding a real problem if I start having mammograms earlier.

More important
Equally important
More important

I'm not afraid to have a biopsy or other tests if my doctor sees a problem on the mammogram.

I don't want to have a biopsy or other tests that I may not need.

More important
Equally important
More important

I'm not afraid of being exposed to small doses of radiation each time I have a mammogram.

I don't want to be exposed to any more radiation than is necessary.

More important
Equally important
More important

My other important reasons:

My other important reasons:

More important
Equally important
More important

Where are you leaning now?

Now that you've thought about the facts and your feelings, you may have a general idea of where you stand on this decision. Show which way you are leaning right now.

Start mammograms at age 40 (or anytime in your 40s)

Start mammograms at age 50

Leaning toward
Undecided
Leaning toward

What else do you need to make your decision?

Check the facts

1.

Does the risk of breast cancer go up as you get older?

  • Yes That's right. The risk for breast cancer goes up as you get older. In general, women younger than 50 are at a lower risk for breast cancer.
  • No Sorry, that's not right. The risk for breast cancer goes up as you get older. In general, women younger than 50 are at a lower risk for breast cancer.
  • I'm not sure It may help to go back and read "Get the Facts." The risk for breast cancer goes up as you get older. In general, women younger than 50 are at a lower risk for breast cancer.
2.

Can having mammograms help save lives?

  • Yes That's right. Studies show that a small number of women who have mammograms may be less likely to die from breast cancer. Since the risk for breast cancer goes up as you get older, women ages 50 to 70 are more likely to benefit from having mammograms than women who are in their 40s.
  • No Sorry, that's not right. Studies show that a small number of women who have mammograms may be less likely to die from breast cancer. Since the risk for breast cancer goes up as you get older, women ages 50 to 70 are more likely to benefit from having mammograms than women who are in their 40s.
  • I'm not sure It may help to go back and read "Get the Facts." Studies show that a small number of women who have mammograms may be less likely to die from breast cancer. Since the risk for breast cancer goes up as you get older, women ages 50 to 70 are more likely to benefit from having mammograms than women who are in their 40s.
3.

If your mammogram shows an abnormal result, does that mean you have breast cancer?

  • Yes Sorry, that's not right. Mammograms may show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.
  • No That's right. Mammograms may show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.
  • I'm not sure It may help to go back and read "Get the Facts." Mammograms may show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.

Decide what's next

1.

Do you understand the options available to you?

2.

Are you clear about which benefits and side effects matter most to you?

3.

Do you have enough support and advice from others to make a choice?

Certainty

1.

How sure do you feel right now about your decision?

Not sure at all
Somewhat sure
Very sure

Your Summary

Here's a record of your answers. You can use it to talk with your doctor or loved ones about your decision.

Your decision  

Next steps

Which way you're leaning

How sure you are

Your comments

Your knowledge of the facts  

Key concepts that you understood

Key concepts that may need review

Getting ready to act  

Patient choices

Credits and References

Credits
Author Healthwise Staff
Primary Medical Reviewer Adam Husney, MD - Family Medicine
Specialist Medical Reviewer Joann G. Elmore, MD, MPH, FACP - Internal Medicine

References
Citations
  • American Cancer Society (2012). American Cancer Society Guidelines for the Early Detection of Cancer. Atlanta: American Cancer Society. Available online: http://www.cancer.org/Healthy/FindCancerEarly/CancerScreeningGuidelines/american-cancer-society-guidelines-for-the-early-detection-of-cancer.
  • American College of Obstetricians and Gynecologists (2011). Breast cancer screening. ACOG Practice Bulletin No. 122. Obstetrics and Gynecology, 118: 372–382.
  • U.S. Preventive Services Task Force (2009). Screening for breast cancer. Available online: http://www.uspreventiveservicestaskforce.org/uspstf/uspsbrca.htm.
You may want to have a say in this decision, or you may simply want to follow your doctor's recommendation. Either way, this information will help you understand what your choices are so that you can talk to your doctor about them.

Breast Cancer Screening: When Should I Start Having Mammograms?

Here's a record of your answers. You can use it to talk with your doctor or loved ones about your decision.
  1. Get the facts
  2. Compare your options
  3. What matters most to you?
  4. Where are you leaning now?
  5. What else do you need to make your decision?

1. Get the Facts

Your options

  • Start having screening mammograms at age 40 (or anytime in your 40s).
  • Start having screening mammograms at age 50.

This information is for women who are choosing to have screening mammograms and who are at average risk for breast cancer. It is not for women who are at high risk. If you don't already know your breast cancer risk, you can ask your doctor. Or you can look it up at www.cancer.gov/bcrisktool/.

Key points to remember

  • Mammograms can find some breast cancers early, when the cancer may be more easily treated. Studies show that a small number of women who have mammograms may be less likely to die from breast cancer.
  • The risk for breast cancer goes up as you get older. In general, women younger than 50 are at a lower risk for breast cancer. Because of this, women ages 50 to 70 are more likely to benefit from having mammograms than women who are in their 40s.
  • Mammograms may miss some breast cancers. And some cancers that are found may still be fatal, even with treatment.
  • Mammograms may show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.
  • Mammograms may find cancers that will never cause a problem (called overdiagnosis). Some breast cancers never grow or spread and are harmless. You might have this type of cancer, but a mammogram can't tell whether it's harmless. So you may get cancer treatment—including surgery, radiation, or chemotherapy—that you don't need.
  • If you have health problems that would make it too hard to go through cancer treatment, or if you would not want to have treatment, there may not be a good reason to have a mammogram.
FAQs

What is a mammogram?

A mammogram is an X-ray of the breast that is used to screen for and diagnose breast cancer.

There are two types of mammograms.

  • A screening mammogram looks for signs of breast cancer before any symptoms appear.
  • A diagnostic mammogram looks for breast cancer in women who have symptoms. Or it is done if you had an abnormal screening mammogram. It's also used to find an area of suspicious breast tissue to remove for a biopsy.

This decision aid is about screening mammograms.

What are the benefits of having a mammogram?

Mammograms can find some breast cancers early, when the cancer may be more easily treated. Often a mammogram can find cancers that are too small for you or your doctor to feel.

Studies show that a small number of women who have mammograms may be less likely to die from breast cancer.

The risk for breast cancer goes up as you get older. In general, women younger than 50 are at a lower risk for breast cancer. Because of this, women ages 50 to 70 are more likely to benefit from having a mammogram than women who are in their 40s.

What are the risks of having a mammogram?

Each time you have a mammogram, there is a risk that the test:

  • May miss some breast cancers. And some cancers that are found may still be fatal, even with treatment.
  • May show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.
  • May find cancers that will never cause a problem (called overdiagnosis). Some breast cancers never grow or spread and are harmless. You might have this type of cancer, but a mammogram can't tell whether it's harmless. So you may get cancer treatment—including surgery, radiation, or chemotherapy—that you don't need.
  • Will briefly expose you to very small amounts of radiation. While the risk from being exposed to radiation from a mammogram is low, it can add up over time.

What do the numbers tell us about the benefits and risks of having a mammogram?

Benefits

Breast cancers found in women having annual mammograms over 10 years*1
Ages 40–49 About 19 out of 1,000 women
Ages 50–59 About 30 out of 1,000 women
Ages 60–69 About 44 out of 1,000 women

*Based on the best available evidence (evidence quality: moderate to high)

Breast cancer deaths over 10 years with or without annual mammograms*1
Women who have mammograms Women who don't have mammograms Mammograms making a life-saving difference
Ages 40–49 About 3 out of 1,000 will die of breast cancer Between 3 and 4 out of 1,000 will die of breast cancer For less than 1 out of 1,000 women
Ages 50–59 About 6 out of 1,000 will die of breast cancer About 7 out of 1,000 will die of breast cancer For about 1 out of 1,000 women
Ages 60–69 About 9 out of 1,000 will die of breast cancer About 13 out of 1,000 will die of breast cancer For about 4 out of 1,000 women

*Based on the best available evidence (evidence quality: moderate to high)

Breast cancer diagnosis

Mammograms can find some breast cancers early, when the cancer may be more easily treated. Often a mammogram can find cancers that are too small for you or your doctor to feel.

Take a group of women who have a mammogram every year for 10 years .1

  • About 19 out of 1,000 women ages 40 to 49 will be diagnosed with breast cancer. This means that about 981 won't.
  • About 30 out of 1,000 women ages 50 to 59 will be diagnosed with breast cancer. This means that about 970 won't.
  • About 44 out of 1,000 women ages 60 to 69 will be diagnosed with breast cancer. This means that about 956 won't.

Survival

Studies show that a small number of women who have mammograms may be less likely to die from breast cancer. Since the risk for breast cancer goes up as you get older, women ages 50 to 70 are more likely to benefit from having a mammogram than women who are in their 40s.

Take a group of women who have a mammogram every year for 10 years .1

  • Mammograms will make a life-saving difference for less than 1 out of 1,000 women ages 40 to 49. This means that for more than 999 of them, having mammograms won't make a difference.
  • Mammograms will make a life-saving difference for about 1 out of 1,000 women ages 50 to 59. This means that for about 999 of them, having mammograms won't make a difference.
  • Mammograms will make a life-saving difference for about 4 out of 1,000 women ages 60 to 69. This means that for about 996 of them, having mammograms won't make a difference.

The numbers in the tables and narratives include women who are expected to be diagnosed with invasive breast cancer or an early form of noninvasive breast cancer called ductal carcinoma in situ.

Risks

False-positive test results and unnecessary biopsies with annual mammograms over 10 years*1
Number of women who will have at least one false-positive that results in more testing (but turns out not to be cancer) Number of women who will have a biopsy they don't need
Ages 40–49 About 613 out of 1,000 women About 70 out of 1,000 women
Ages 50–59 About 613 out of 1,000 women About 94 out of 1,000 women
Ages 60–69 About 497 out of 1,000 women About 98 out of 1,000 women

*Based on the best available evidence (evidence quality: moderate to high)

Mammograms may show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.

Take a group of women who have a mammogram every year for 10 years .1

  • About 613 out of 1,000 women ages 40 to 49 will have at least one false-positive test result. This means that about 387 won't.
  • About 613 out of 1,000 women ages 50 to 59 will have at least one false-positive test result. This means that about 387 won't.
  • About 497 out of 1,000 women ages 60 to 69 will have at least one false-positive test result. This means that about 503 won't.

Breast cancer screening can also lead to unnecessary biopsies.

Take a group of women who have a mammogram every year for 10 years .1

  • About 70 out of 1,000 women ages 40 to 49 will have a biopsy they don't need. This means that about 930 won't.
  • About 94 out of 1,000 women ages 50 to 59 will have a biopsy they don't need. This means that about 906 won't.
  • About 98 out of 1,000 women ages 60 to 69 will have a biopsy they don't need. This means that about 902 won't.

Mammograms may find cancers that would never have caused a problem if they had not been found through screening (called overdiagnosis). But a mammogram can't tell whether the cancer is harmless. So you may get cancer treatment that you don't need.

Out of 1,000 women who are diagnosed with breast cancer during screening mammograms, experts estimate that about 190 of them may get treatment they don't need.1

The numbers in the tables and narratives include women who are expected to be diagnosed with invasive breast cancer or an early form of noninvasive breast cancer called ductal carcinoma in situ.

Understanding the evidence

Some evidence is better than other evidence. Evidence comes from studies that look at how well treatments and tests work and how safe they are. For many reasons, some studies are more reliable than others. The better the evidence is—the higher its quality—the more we can trust it. The information shown here is based on the best available evidence.1 The evidence is rated using four quality levels: high, moderate, borderline, and inconclusive.

Another thing to understand is that the evidence can't predict what's going to happen in your case. When evidence tells us that 2 out of 100 people who have a certain test or treatment may have a certain result and that 98 out of 100 may not, there's no way to know if you will be one of the 2 or one of the 98.

When do experts advise starting mammograms?

For women who are at average risk for breast cancer, there are no easy answers for when to start having mammograms. Even the experts don't agree on when is the best time to start.

For example:

  • The U.S. Preventive Services Task Force recommends that most women begin screening at age 50, and then have a mammogram every 2 years. The Task Force recommends that women in their 40s be offered screening and allowed to make an informed choice.
  • The American Cancer Society recommends that most women begin screening at age 40, and then have a mammogram every year.

But most experts do agree that all women should be informed about the risks and benefits of mammograms and offered screening by age 50.

When to stop having mammograms is another decision. You and your doctor will decide on the right age to stop screening based on your personal preferences and overall heath.

2. Compare your options

  Start mammograms at age 40 Start mammograms at age 50
What is usually involved?
  • At age 40:
    • You go to your doctor if you notice any changes in your breasts.
    • You may get a mammogram every 1 to 2 years, depending on what you and your doctor decide.
    • If you have an abnormal test result, you may have more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer.
  • Until age 50:
    • You go to your doctor if you notice any changes in your breasts.
  • At age 50, you start getting mammograms. You may get one every 1 to 2 years, depending on what you and your doctor decide.
    • If you have an abnormal test result, you may have more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer.
What are the benefits?
  • Mammograms can find some breast cancers early, when the cancer may be more easily treated.
  • Studies show that a small number of women who have mammograms may be less likely to die from breast cancer.
  • Earlier screening may help you find breast cancer sooner.
  • Mammograms can find some breast cancers early, when the cancer may be more easily treated.
  • Studies show that a small number of women who have mammograms may be less likely to die from breast cancer.
  • Since the risk for breast cancer goes up as you get older, women ages 50 to 70 are more likely to benefit from having a mammogram than women who are in their 40s.
  • By waiting until age 50 to start having mammograms:
    • You avoid the cost and inconvenience of getting a mammogram during your 40s.
    • You limit the number of mammograms that may result in a false-positive test.
    • You limit the number of mammograms that may find a cancer that may never cause a problem.
    • You limit your exposure to radiation.
What are the risks and side effects?
  • Each time you have a mammogram, there is a risk that the test may:
    • Miss some breast cancers. And some cancers that are found may still be fatal, even with treatment.
    • Show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.
    • Find cancers that will never cause a problem (called overdiagnosis). You might have this type of cancer, but a mammogram can't tell whether it's harmless. So you may get cancer treatment—including surgery, radiation, or chemotherapy—that you don't need.
  • By starting mammograms earlier, you increase your chances of getting a false-positive test.
  • By starting mammograms earlier, you increase your chances of finding a cancer that may never cause a problem.
  • You are briefly exposed to very small amounts of radiation each time you have a mammogram.
  • Each time you have a mammogram, there is a risk that the test may:
    • Miss some breast cancers. And some cancers that are found may still be fatal, even with treatment.
    • Show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.
    • Find cancers that will never cause a problem (called overdiagnosis). You might have this type of cancer, but a mammogram can't tell whether it's harmless. So you may get cancer treatment—including surgery, radiation, or chemotherapy—that you don't need.
  • You are briefly exposed to very small amounts of radiation each time you have a mammogram.
  • There is a small risk that a cancer that develops before age 50 may not be found early. You could miss the chance to start treatment early when it has a higher chance of success.

Personal stories

Personal stories about when to start having mammograms

These stories are based on information gathered from health professionals and consumers. They may be helpful as you make important health decisions.

"No one in my family has ever had breast cancer. So I'm not at high risk for getting it. I talked with my doctor about this, and I read all of the information I could. My doctor says it's my decision, but she is here to answer any questions and talk it over. I'm worried about false positives. I have a friend who has had two biopsies, and many sleepless nights, and it turned out to be nothing. I'm having a tough time deciding. I think for me the best decision is no decision. I'll keep reading and thinking about it. I'm okay with this."

— Keiko, 41

"I'm not really worried about getting breast cancer, so I've decided to wait until I'm 50 to start having mammograms. I just turned 40, and I've always been healthy and active. Plus, I don't have any extra risk factors. In the meantime, I'm going to mention any changes I notice in my breasts to my doctor."

— Helen, 40

"My friend was diagnosed with late-stage breast cancer after finding a lump in her breast when she was 48. She didn't have any risk factors for the disease, so she hadn't had any mammograms before then. I can't help but think that maybe if she'd had a mammogram a year or two before, the cancer may have been found earlier. I'm not at high risk for breast cancer either, but I'm going to keep having my yearly mammogram just to be sure nothing is wrong."

— Sally, 46

"I travel a lot for my job, and my days are often crammed with back-to-back meetings, so trying to schedule a mammogram is a challenge. But I've managed to do it, and all my mammograms have been normal. Now some doctors are saying that it's okay for women to wait and start having mammograms at 50. I think that's reasonable, and I don't feel like I would be putting myself at much greater risk for missing a cancer by waiting until I'm 50 to get my next one."

— Bella, 44

3. What matters most to you?

Your personal feelings are just as important as the medical facts. Think about what matters most to you in this decision, and show how you feel about the following statements.

Reasons to start mammograms at age 40 (or anytime in your 40s)

Reasons to start mammograms at age 50

I'm worried that I might get breast cancer at an earlier age.

I'm not too worried that I might get breast cancer at an earlier age.

             
More important
Equally important
More important

I think starting mammograms earlier is worth the increased risk of having a false-positive test result if it could find cancer early.

I think the chance of having a false-positive test result is more likely than the test finding a real problem if I start having mammograms earlier.

             
More important
Equally important
More important

I'm not afraid to have a biopsy or other tests if my doctor sees a problem on the mammogram.

I don't want to have a biopsy or other tests that I may not need.

             
More important
Equally important
More important

I'm not afraid of being exposed to small doses of radiation each time I have a mammogram.

I don't want to be exposed to any more radiation than is necessary.

             
More important
Equally important
More important

My other important reasons:

My other important reasons:

   
             
More important
Equally important
More important

4. Where are you leaning now?

Now that you've thought about the facts and your feelings, you may have a general idea of where you stand on this decision. Show which way you are leaning right now.

Start mammograms at age 40 (or anytime in your 40s)

Start mammograms at age 50

             
Leaning toward
Undecided
Leaning toward

5. What else do you need to make your decision?

Check the facts

1. Does the risk of breast cancer go up as you get older?

  • Yes
  • No
  • I'm not sure
That's right. The risk for breast cancer goes up as you get older. In general, women younger than 50 are at a lower risk for breast cancer.

2. Can having mammograms help save lives?

  • Yes
  • No
  • I'm not sure
That's right. Studies show that a small number of women who have mammograms may be less likely to die from breast cancer. Since the risk for breast cancer goes up as you get older, women ages 50 to 70 are more likely to benefit from having mammograms than women who are in their 40s.

3. If your mammogram shows an abnormal result, does that mean you have breast cancer?

  • Yes
  • No
  • I'm not sure
That's right. Mammograms may show an abnormal result when it turns out there wasn't any cancer (called a false-positive). This means you may need more tests—such as another mammogram, a breast ultrasound, or a biopsy—to make sure you don't have cancer. These tests can be harmful and cause a lot of worry.

Decide what's next

1. Do you understand the options available to you?

2. Are you clear about which benefits and side effects matter most to you?

3. Do you have enough support and advice from others to make a choice?

Certainty

1. How sure do you feel right now about your decision?

         
Not sure at all
Somewhat sure
Very sure

2. Check what you need to do before you make this decision.

  • I'm ready to take action.
  • I want to discuss the options with others.
  • I want to learn more about my options.
 
Credits
By Healthwise Staff
Primary Medical Reviewer Adam Husney, MD - Family Medicine
Specialist Medical Reviewer Joann G. Elmore, MD, MPH, FACP - Internal Medicine

References
Citations
  1. Pace LE, Keating NL (2014). A systematic assessment of benefits and risks to guide breast cancer screening decisions. JAMA, 311(13): 1327–1335. http://jama.jamanetwork.com/article.aspx?articleid=1853165. Accessed January 16, 2015.

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