September 30, 2015 — Few women who are using hormone-blocking drugs to treat early-stage breast cancer would benefit from undergoing chemotherapy, a new study found, according to AP/U.S. News & World Report.
According to AP/U.S. News & World Report, more than 100,000 U.S. women each year are diagnosed with the most common type of breast cancer, which is hormone-positive, has not yet spread to lymph nodes, and is not responsive to the drug Herceptin. Women with this type of breast cancer usually undergo surgery, undergo a multi-year regimen that blocks hormones and are encouraged to undergo chemotherapy as a precaution. Although most women with this type of breast cancer do not require chemotherapy, health care providers have no accurate means to determine which patients can safely forego the treatment.
In 2004, California-based Genomic Health released Oncotype DX, which can accurately measure genes that control cancer cell growth and gauge the effectiveness of hormone therapy. The test costs $4,175, which Medicare and many insurers cover, and similar alternatives to Oncotype DX exist.
The study, published Monday in the New England Journal of Medicine, was sponsored by the National Cancer Institute. It studied 10,253 women with this type of breast cancer.
Women were sorted into three groups based on risk of recurrence as determined by the Oncotype test: 16% were low risk, 67% were intermediate risk and 17% were high risk (Marchione, AP /U.S. News & World Report, 9/28). The women in the low-risk cohort were given hormone therapy exclusively (Sparano et al., NEJM, 9/28). The study is ongoing for the intermediate-risk group, which was randomly assigned hormone therapy alone or hormone and chemotherapy, and the high-risk group, which was given hormone therapy plus chemotherapy.
The study found that, after five years, about 99% of low-risk participants did not have any recurrence of breast cancer, about 98% were alive and about 94% did not have any invasive cancer.
Hope Rugo -- a breast cancer specialist at University of California-San Francisco, who had no involvement with the study -- said, "These patients who had low risk scores by Oncotype did extraordinarily well at five years," adding, "There is no chance that for these patients, that chemotherapy would have any benefit."
Clifford Hudis of New York's Memorial Sloan Kettering Cancer Center, an independent expert, said, "There is really no chance that chemotherapy could make that number better." Using the genetic test "lets us focus our chemotherapy more on the higher risk patients who do benefit," Hudis said, adding that he hopes more genetic tests will develop to encourage price competition and improve accuracy (AP/U.S. News & World Report, 9/28).