Many women receive chemotherapy and a hormonal therapy medicine such as tamoxifen after breast cancer surgery to reduce the risk of the cancer coming back. The study reviewed here showed that, either alone or in combination, chemotherapy and tamoxifen also reduce the risk that a new cancer will develop in the opposite (contralateral) breast.
Chemotherapy reduced the risk of a new cancer in the other breast by 43% over 10 years. Tamoxifen reduced the risk of a new cancer in the other breast by 34% over 5 years.
These results are important because once a woman is diagnosed with breast cancer, her risk of developing a new, second breast cancer in the other breast is 2 to 6 times higher than the breast cancer risk of a woman who's never been diagnosed.
If you've been diagnosed with breast cancer, you and your doctor will decide whether treatments like chemotherapy and hormonal therapy are right for you. Worrying about recovering from treatment and getting healthy, plus being anxious about the cancer possibly coming back is hard enough without having to think about the possibility of a new, second breast cancer in the other breast. The good news is that the treatments your doctor may recommend to lower the risk of the cancer coming back also can lower your risk of developing a new, second breast cancer.
If you've been treated for breast cancer, visit the Lowering Risk for People with a Personal History area to learn more about steps you can take to lower your risk of developing a new and different breast cancer.
NEW YORK (Reuters Health) - Among women with breast cancer, both chemotherapy and tamoxifen reduce the long-term risk of developing a second cancer in the other breast, researchers report in the January 2, 2008 issue of the Journal of the National Cancer Institute. The risk reduction persists for at least 10 years with chemotherapy and for 5 years with tamoxifen.
For breast cancer patients the risk of developing cancer in the other breast is two to six times greater than the breast cancer risk of the general public. Previous reports have shown that both chemotherapy and tamoxifen reduce the risk of "contralateral" breast cancer, but the length of this reduced risk was unclear.
Dr. Lisbeth Bertelsen, from the Danish Cancer Society in Copenhagen, and colleagues report investigated the relationship between tamoxifen and chemotherapy -- either alone or in combination -- and the risk of cancer in the opposite breast among American and Danish women who were first diagnosed with breast cancer before age 55.
The study included 1,158 women who developed cancer in one breast and an additional 634 who initially had cancer in one breast then developed a second cancer in the other breast.
Results showed that chemotherapy was associated with a 43 percent reduced risk for developing cancer in the opposite breast, compared with no chemotherapy. This risk reduction lasted up to 10 years after the initial cancer diagnosis.
Tamoxifen use was associated with a 34 percent reduced risk of a second breast cancer, compared with no tamoxifen use, and this reduction continued for five years after diagnosis.
SOURCE: Journal of the National Cancer Institute, January 2, 2008.
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