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There has been some controversy surrounding the length of time women with estrogen receptor (ER)-positive breast cancer should take the selective estrogen receptor modulator tamoxifen. Adam Brufsky, MD, PhD, explains that, for most women, tamoxifen is given for 5 to 10 years. For someone with a smaller tumor (eg, 1 to 2 centimeters) who is ER-positive and node negative, 5 years of therapy with tamoxifen may be appropriate. By contrast, someone with 8 to 10 positive nodes or a larger tumor (eg, 5 to 7 centimeters) may benefit from extended therapy with tamoxifen.
Genomic assays are available that can help determine the prognosis in women with early stage breast cancer. The Breast Cancer Index (BCI) categorizes ER-positive, lymph node negative breast cancer patients as low-, intermediate-, or high-risk. Brufsky notes that the BCI appears to outperform some of the other assays on the market in terms of predicting 5- to 10-year recurrence. The 5-year recurrence rate is approximately 13% for patients who are intermediate-risk and approximately 3% to 4% for those who are low-risk according to the BCI, he says.
One of the obstacles in using BCIs centers on reimbursement, notes Brufsky. He predicts a greater acceptance among payers in the future, given the usefulness of these tools in determining the appropriateness of certain therapies. Brufsky adds that it is important to weigh the risk and benefits for each patient—tamoxifen lowers the risk for recurrence but also carries a small risk of endometrial cancer and blood clots.