Second Cancers After Breast Cancer

Breast cancer survivors can be affected by a number of health problems, but often a major concern is facing cancer again.

If this happens, it’s most often the result of the breast cancer coming back after treatment. This is called a breast cancer recurrence. But some cancer survivors develop a new, unrelated cancer later on. This is called a second cancer.

Women who’ve had breast cancer can still get other cancers. Although most breast cancer survivors don’t get cancer again, they are at higher risk for getting some types of cancer.

The most common second cancer in breast cancer survivors is another breast cancer. (This is different from the first cancer coming back.) The new cancer can develop in the opposite breast, or in the same breast for women who were treated with breast-conserving surgery (such as a lumpectomy).

Depending on which types of cancer treatment they received (and other factors), some breast cancer survivors might also be at higher-than-average risk for:

• Salivary gland cancer
• Esophagus cancer
• Stomach cancer
• Colon cancer
• Uterine cancer
• Ovarian cancer
• Thyroid cancer
• Soft tissue cancer (sarcoma)
• Melanoma of the skin
• Acute myeloid leukemia (AML)

Of course, breast cancer survivors can get other types of cancer as well.

The increased risk for these cancers can be due to a number of factors, including genetic risk factors and the use of some types of breast cancer treatments. For example:

• Women with inherited mutations in one of the BRCA genes have an increased risk of breast cancer, ovarian cancer, and some other cancers.
• Radiation therapy to the chest as part of treatment seems to increase the risk for lung cancer (especially in women who smoke), sarcomas (cancers of connective tissues such as blood vessels and bones), and certain blood cancers, such as leukemia and myelodysplastic syndrome (MDS). Overall, though, the increase in risk is small, and the overall risk of these cancers is still low. 
• Certain chemotherapy (chemo) drugs can increase the risk of developing leukemia and myelodysplastic syndrome (MDS) slightly.
• While tamoxifen can lower the chance of hormone receptor-positive breast cancer coming back (as well as the risk of getting a second breast cancer), it can increase the risk of uterine cancer (endometrial cancer and uterine sarcoma). Still, the overall risk of uterine cancer in most women taking tamoxifen is low, so the benefits of this drug in treating breast cancer are generally greater than the small increase in risk of a second cancer.

Follow-up after breast cancer treatment

If you have completed treatment for breast cancer, you should still see your doctor regularly, both to look for signs that the cancer might have come back and to look for any late effects from cancer treatment.

If you have not had both breasts removed, you still need regular mammograms to look for breast cancer (either a recurrence of the cancer or a new breast cancer). See Follow-up Care After Breast Cancer Treatment for more on the other types of tests you might need after treatment.

You should also follow the American Cancer Society guidelines for the early detection of cancer, such as those for colorectal cancer and cervical cancer. Screening tests can often find these cancers early, when they are likely to be easier to treat. In some cases, the tests might even help prevent these cancers if pre-cancers are found and treated. For women who have had breast cancer, most experts do not recommend any additional testing to look for second cancers unless you have symptoms. 

Let your doctor know about any new symptoms or problems, because they could be caused by the breast cancer coming back or by a new disease or second cancer. For example, abnormal menstrual bleeding, such as bleeding or spotting after menopause or between periods, can be a symptom of uterine cancer.

Can I lower my risk of getting a second cancer?

There's no sure way to prevent all cancers, but there are steps you can take to lower your risk and stay as healthy as possible. Getting the recommended early detection tests, as mentioned above, is one way to do this.

It’s also important to stay away from tobacco products. Smoking increases the risk of many cancers, including some of the second cancers that are more likely after breast cancer.

To help maintain good health, breast cancer survivors should also follow the ACS Guidelines on Diet and Physical Activity for Cancer Prevention:

• Get to and stay at a healthy weight.
• Keep physically active and limit the time you spend sitting or lying down.
• Follow a healthy eating pattern that includes plenty of fruits, vegetables, and whole grains, and limits or avoids red and processed meats, sugary drinks, and highly processed foods.
• It's best not to drink alcohol. Women who drink should have no more than 1 drink per day.

These steps may also lower the risk of some other health problems.

See Second Cancers in Adults for more information about causes of second cancers.