In an updated clinical practice guideline, the American Society of Clinical Oncology has named the Breast Cancer Index (BCI) as the only genomic test that should be used to guide extended endocrine therapy decisions for women with early-stage, hormone receptor–positive breast cancer. The update applies to women who are node negative or have one to three positive nodes treated with 5 years of endocrine therapy and no sign of recurrence.
The update was published in the Journal of Clinical Oncology. It also gives more specific details on how to apply other, previously recommended, genomic tests to guide treatment choices.
More than half of breast cancer deaths occur after 5 years of tamoxifen therapy. The National Surgical Adjuvant Breast and Bowel Project (NSABP)- B14 trial, published in 2001, showed no benefit to extending tamoxifen therapy to 10 years, but other studies have produced mixed results.
Extended endocrine therapy may reduce the risk of recurrence, but significant side effects can impact quality of life, including osteoporosisbone fractures, and joint pain. The uncertain benefits of extended endocrine therapy, combined with its side effects and impact on quality of life, has generated interest in genomic tests to identify patients most likely to benefit.
