Some women diagnosed with early-stage breast cancer in one breast choose to have both breasts removed. Removing the healthy breast is called "contralateral prophylactic mastectomy." In most cases, the healthy breast is removed because a woman has many risk factors for breast cancer or understandable fears that a new, second breast cancer might develop in the healthy breast.
A large study found that women diagnosed with early-stage breast cancer who chose to have contralateral prophylactic mastectomy were 16% less likely to die from breast cancer in the 4 years after diagnosis than women who didn't have the healthy breast removed. Still, it's unclear if removing the healthy breast is the reason for the better survival.
Women diagnosed with early-stage breast cancer in one breast have a higher-than-average risk of developing a new, second cancer in the other breast. This risk is very high for some women and only a little higher than average for other women. Factors that can increase this risk are being diagnosed with hormone-receptor-negative breast cancer and testing positive for the BRCA1 or BRCA2 genes.
If the risk of a new cancer in the opposite breast is very high, doctors may recommend contralateral prophylactic mastectomy. Even if their doctor doesn't recommend removing the opposite breast, some women choose contralateral prophylactic mastectomy because they're understandably afraid of developing another breast cancer. Some women also may ask for contralateral prophylactic mastectomy to have more balanced cosmetic results after reconstructive surgery on both breasts.
This study looked at the outcomes of more than 107,000 women diagnosed with early-stage breast cancer who had mastectomy as part of their treatment. About 8,900 of those women also chose to have contralateral prophylactic mastectomy. All of the women were followed for about 4 years so the researchers could compare the outcomes of the women who had contralateral prophylactic mastectomy to women who didn't.
Overall, women who had contralateral prophylactic mastectomy were 16% less likely to have died from breast cancer, compared women who didn't have the opposite breast removed:
- Survival gains were greatest in premenopausal women younger than 50 diagnosed with stage I or stage II hormone-receptor-negative breast cancer.
- 88.5% of women younger than 50 who had the opposite breast removed were alive after nearly 4 years, compared to 83.7% of those who didn't, a 32% increase in survival.
It's important to know that most of the women were alive 4 years after surgery, whether or not they had contralateral prophylactic mastectomy.
The researchers aren't sure whether the link between contralateral prophylactic mastectomy and better survival is related to removing the healthy breast or to other health/breast cancer factors or treatment choices -- such as getting chemotherapy after surgery.
Other doctors who looked at the study results noticed that women younger than 50 diagnosed with hormone-receptor-negative breast cancer were a large portion of the group that chose to have contralateral prophylactic mastectomy and had better survival. These doctors said that removing the opposite breast might not have the same benefits for older women diagnosed with hormone-receptor-positive breast cancer.
Women younger than 50 diagnosed with hormone-receptor-negative breast cancer have a higher risk of the cancer coming back (recurrence) and of developing a new cancer in the future compared to older women diagnosed with hormone-receptor-positive breast cancer. So it makes sense that contralateral prophylactic mastectomy might improve survival in some younger women diagnosed with early-stage, hormone-receptor-negative breast cancer.In January 2009, Breastcancer.org reviewed an earlier study looking at the benefits of contralateral prophylactic mastectomy. That study found that women with a specific breast cancer risk profile and/or one of three specific breast cancer characteristics got the most benefit from removing the opposite breast:
- a breast cancer risk assessment tool score (also called a Gail score) of more than 1.67% risk; the score is based on personal health questions that women and their doctors answer together and estimates the risk of developing invasive breast cancer in the next 5 years
- a pathology report showing invasive lobular breast cancer (ILC), less common than invasive ductal breast cancer (IDC)
- cancer in more than one location in the breast
Women with one of these three factors were more than 3 times more likely than women who had none of the factors to develop breast cancer in the opposite breast. So the results suggested that contralateral prophylactic mastectomy makes the most sense for women with any of the factors.
If you've been diagnosed with early-stage breast cancer, ask your doctor about ALL your treatment and risk reduction options. Prophylactic mastectomy is only one of these options and it's a very aggressive step. It may be the right decision for you, but do talk to your doctor to make sure that your decisions are based on your actual risk and not only fear. Ask about your Gail score and how the information in your pathology report may affect your future risk. If you're not completely sure about removing the opposite breast, waiting to decide until after your breast cancer treatment plan is complete could be a good idea. Together, you and your doctor can make the decisions that are best for you and your unique situation.