An abnormality in two genes can make a common class of chemotherapy drugs used to fight breast cancer less effective, U.S. researchers said on Sunday in a finding that could help doctors better tailor treatments, according to Reuters. They said changes in two genes on a small region of chromosome 8q made tumors resist the effects of drugs called anthracyclines, but not other types of chemotherapy drugs. "This is useful because it helps select who might be resistant to anthracyclines," said Dr. Andrea Richardson of the Dana-Farber Cancer Institute in Boston, whose study appears in the journal Nature Medicine. "This can potentially be used to help guide therapy on a more personalized way based on a patient's own tumor. That's why it's exciting," Richardson said in a telephone interview. She said it may be possible to develop a genetic test to better tailor treatments to a patient's individual tumor. Doctors already can test for certain genes to tell whether a woman's breast cancer is sensitive to estrogen, making her a candidate for hormone-blocking drugs such as tamoxifen. Breast cancer patients whose tumors generate a protein called HER-2, which can fuel cancer growth, are often treated with Herceptin, or trastuzumab, a drug developed by Genentech, now a unit of Roche Holding AG. Last month, a study presented at the American Association for Cancer Research San Antonio Breast Cancer Symposium found that a gene-based test called Oncotype DX made by Genomic Health Inc helped identify women who are not likely to benefit at all from chemotherapy.
