Short-term versus long-term tamoxifen use in BRCA mutation carriers

The authors aimed to determine whether the duration of tamoxifen (Nolvadex) treatment could significantly affect the risk of recurrent (the cancer returns) cancer.

Genetic mutations can often cause harmful changes in our body. BRCA1 and BRCA2 are two such genes that are known as cancer susceptibility genes. Women with these mutations face a lifetime risk of developing breast cancer. Following cancer in one breast, these mutations increase the risk of developing cancer in the other breast. Tamoxifen treatment has been known to reduce this risk. It is not well understood, however, whether or not the length of treatment time has significant effects on a woman’s risk of developing cancer in the other breast.

The aim of this study was to evaluate the effects of tamoxifen duration on the risks of developing cancer  in the other breast in BRCA mutation carriers. A total of 1504 women were evaluated in this study.  411 of these women had cancer in both breasts, while 1093 had cancer in one breast.

331 patients had used tamoxifen. The duration of tamoxifen use was split between up to one year, 1-4 years and 4 or more years. 24.7% of those with cancer in one breast and 14.8% of those with cancer in both breasts underwent tamoxifen treatment.

There was no significant difference in survival outcome between BRCA1 and BRCA2 breast cancer cases. BRCA1 carriers who were treated with tamoxifen had a 42% reduced risk of developing cancer in the other breast. BRCA2 carriers showed a 61% reduced risk.

Women treated for up to 1 year had a 63% reduced risk of cancer in the other breast. Those treated for 1-4 years had a 47% reduced risk, and those treated for 4 or more years had a 17% reduced risk.

A subset of women were treated with tamoxifen for a year or less who then developed cancer in the other breast. In those women, the cancer did not develop for an average of 2 years following treatment.

The authors concluded that tamoxifen treatment can reduce the risk of contralateral breast cancer in carriers of the BRCA1 and BRCA2 mutations. They also suggested that this treatment does not have to be long-term, as treatment up to one year can still provide protective anti-cancer effects.

This study does not imply that tamoxifen courses should be shortened. The length of treatment time should be discussed with your doctor to determine what is appropriate.