Most inherited cases of breast cancer are associated with one of two abnormal breast cancer genes: BRCA1 (BReast CAncer gene one) and BRCA2 (BReast CAncer gene two). Women with an abnormal BRCA1 or BRCA2 gene have up to an 85% risk of developing breast cancer by age 70. Women with an abnormal BRCA1 or BRCA2 gene who have been diagnosed with disease also have a higher risk of developing a new, second breast cancer compared to women who don't have an abnormal breast cancer gene. Women with an abnormal BRCA1 or BRCA2 gene also have a higher-than-average risk of ovarian cancer.
The results of two studies were presented at the 2010 European Breast Cancer Symposium.
The first study compared surgery options for 655 women with an abnormal BRCA1 or BRCA2 gene who had been diagnosed with breast cancer:
- 302 women had lumpectomy plus radiation therapy
- 355 women had mastectomy; 103 women who had mastectomy also got radiation therapy
The women were followed for about 8 to 9 years.
Survival rates were the same no matter which type of surgery the women had.
Still, women with an abnormal BRCA1 or BRCA2 gene who had lumpectomy plus radiation were between 4 and 5 times more likely to develop another breast cancer (either the same cancer coming back or a new breast cancer) in the same breast compared to women with an abnormal BRCA1 or BRCA2 gene who had mastectomy. But when the women who had lumpectomy plus radiation also had chemotherapy after surgery, their risk of developing another breast cancer was about the same as the women who had mastectomy.
Based on the results, the researchers suggested that lumpectomy plus radiation therapy could be a good choice for women with an abnormal breast cancer gene, but only if chemotherapy is included in the treatment plan.
After a breast cancer diagnosis, women with an abnormal breast cancer gene also may consider removing the other healthy breast, called contralateral prophylactic mastectomy. Research has shown that contralateral prophylactic mastectomy lowers the risk of breast cancer developing in the healthy breast. In the second study, the researchers looked at whether contralateral prophylactic mastectomy lowered the risk of developing metastatic breast cancer (breast cancer that has spread outside the breast area to another part of the body) or helped improve survival rates in women with an abnormal breast cancer gene.
The researchers followed 390 women with an abnormal breast cancer gene who had been diagnosed with breast cancer for about 6 years:
- 138 women had contralateral prophylactic mastectomy
- 252 didn't have contralateral prophylactic mastectomy
In this study, contralateral prophylactic mastectomy didn't lower the risk of developing metastatic breast cancer and also didn't improve overall survival in women with an abnormal breast cancer gene.
Still, it's important to remember that other research has shown that contralateral prophylactic mastectomy lowers the risk of developing a new breast cancer in the healthy breast.
If you have an abnormal breast cancer gene and have been diagnosed with breast cancer, you and your doctor need to consider the risks associated with an abnormal breast cancer gene as well as the specific characteristics of the cancer and your preferences as you develop your treatment plan.
Lumpectomy plus radiation may be a good choice for you, but the first study reviewed here suggests that chemotherapy also should be part of your treatment plan.
Deciding to have the healthy breast removed also may make sense for you as you try to do all you can to reduce your future risk. Still, you may want to talk to your doctor about ALL of your risk reduction options. Contralateral prophylactic mastectomy is only one of these options and is a very aggressive step. While it may be the right decision for you, give yourself the time you need to consider your decision carefully. Prophylactic mastectomy doesn't have to be done at the same time as lumpectomy or mastectomy. Together, you and your doctor can make the decisions that are best for you and your unique situation.
Editor’s note: In 2014, a study found that an abnormal PALB2 gene increases breast cancer risk 5 to 9 times higher than average. Research is being planned to see if treatment strategies need to be tailored for cancers caused by this genetic abnormality.