Breast cancer screening is a way in which doctors check the breasts for early signs of cancer in those who have no symptoms of breast cancer. The main test used to screen for breast cancer is a special kind of X-ray called a mammogram.

The goal of breast cancer screening is to find cancer early, before it has a chance to grow, spread, or cause problems. Studies show that being screened for breast cancer lowers the chance that someone will die of the disease.

Who should be screened for breast cancer?

Different experts have different recommendations for screening. Starting at the age of 40, it's important to talk to your doctor or nurse about the benefits and drawbacks of screening and decide, with your doctor or nurse's help, whether to get screening and when. If you're under 40 but have a relative who got breast cancer at a young age, you should also talk to your doctor or nurse.

People aged 40 to 74, and some older people who are healthy, might be offered screening with mammograms. Some who are at high risk of breast cancer might need to begin screening at a younger age. This might include people who:

  • Carry genes that increase their risk of breast cancer, such as the BRCA genes
  • Have close relatives (such as a parent, sibling, child) who got breast cancer at a young age

What are the benefits of being screened for breast cancer?

The main benefit of screening is that it helps doctors find cancer early, when it might be easier to treat. This lowers the chances of dying of breast cancer.

What are the drawbacks to being screened for breast cancer?

The drawbacks include:

  • False positives – Mammograms sometimes give false positive results. This means they suggest you have cancer when you do not. This can lead to unneeded worry and to more tests—including a biopsy, which, in some cases, can be painful. False positive results are more likely to happen in people younger than 50 than they are in older people.
  • Overdiagnosis – Sometimes mammograms find cancer that would never have affected your health. This is called "overdiagnosis." It can be a problem because treating these cancers does not have any benefit and can actually cause harm. For example, you might get surgery or chemotherapy to treat a cancer that never would have caused problems if it hadn't been found. There is no way to know which cancers found by screening will lead to problems and which won't.
  • Radiation exposure – Like all X-rays, mammograms expose you to some radiation. But, studies show that the number of lives saved by finding cancer early greatly outweighs the very small risks that come from radiation exposure.

What happens during a mammogram?

Before the mammogram, you will be asked to undress from the waist up and put on a hospital gown. Your breasts will be x-rayed one at a time, and each breast is x-rayed twice. Each is x-rayed once from the top down and once from side-to-side so that the radiologist can get a good look at all the tissue. To make the breast tissue easier to see, a nurse or technician will flatten each breast between two panels. This can be uncomfortable, but it lasts only a few seconds. If possible, avoid scheduling your mammogram just before or during your period. Breasts are extra sensitive at that time. Also, do not use underarm deodorant or powder on the day of your appointment.

What happens after a mammogram?

If a radiologist (the doctor who will look at your X-ray) is able to look at your mammogram right away, you might get the results the same day. If not, you should get a phone call or letter with your results within 30 days. If you do not hear back about your results, call your doctor or nurse's office. Do not assume that your mammogram was normal if you hear nothing.

What if my mammogram is abnormal?

If your mammogram is abnormal, don't panic. Nine out of 10 people with an abnormal mammogram turn out not to have breast cancer. You will need more tests to find out what's really going on.

If your doctor thinks your abnormal result is probably not due to cancer, they might suggest that you wait and have another mammogram in six months. If your doctor thinks the abnormal result might be due to cancer, they will probably send you for more tests. You might also have other tests if your doctor needs to get a better view of part of your breast. Other tests could include a more detailed mammogram, called a diagnostic mammogram, or an ultrasound of the breast. Ultrasound tests might also be suggested for those whose mammogram shows very dense breasts. That's because dense breasts can make a mammogram harder to read.

If the other tests still show any suspicious findings, your doctor or nurse will probably order a biopsy. During a biopsy, a doctor takes samples of breast tissue and sends them to the lab to be checked for cancer. Biopsies are usually done by taking some tissue from the breast with a needle during a mammogram or ultrasound. In some cases, biopsies involve a small surgery.

What about breast exams?

Many experts no longer believe that breast exams by a doctor or nurse are helpful for people who have no breast symptoms. Most lumps that are found when a doctor examines the breast turn out not to be cancer. Also, studies have not found that doing both a breast exam and mammogram is better than doing a mammogram alone.

Some people want to do exams on their own breasts. No study has shown that breast self-exams lower the risk of dying from breast cancer, and most experts do not encourage self-exams. Still, if you decide to do breast self-exams, make sure you know how to do them the right way.

Can I have a breast MRI instead of a mammogram?

You might have heard about breast MRIs, but they are not for everyone. Compared with mammograms, breast MRIs give more false positives and sometimes lead to unneeded biopsies. Still, breast MRIs are sometimes used to help find breast cancer in younger adults who have a high risk of breast cancer. Doctors do not recommend breast MRIs to screen for breast cancer in people who do not have a higher risk of breast cancer, and MRIs don't replace mammograms. They are used along with mammograms for the high-risk people who need them.

How often should I have a mammogram?

It is not clear what the best schedule for mammography is. Many experts suggest screening every two years for most people. Some experts suggest yearly screening for younger adults (under age 50 or 55). The schedule for screening might be different for those who have a high risk of breast cancer.

Routine screening with mammograms should continue as long as you are healthy and expected to live for at least 10 more years.