News Feature | May 29, 2014

ASCO Updates Treatment Guidelines For Breast Cancer Drug Tamoxifen

By Marcus Johnson

Tamoxifen, the breast cancer drug which works by blocking the ability of cells to use the estrogen hormone, was recently given new treatment guidelines by the American Society of Clinical Oncology, or ASCO. The ASCO has deemed that the drug should be used for a period of as long as ten years, depending on the type of breast cancer being treated.

Dr. Harold Burstein, the guideline update panel co-chair at the ASCO, released a statement on the matter. “Tamoxifen taken for five years has been the standard . . . but we now have evidence to recommend up to 10 years of tamoxifen for women with hormone receptor-positive breast cancer,” he said.

The new guidelines affect women who are suffering from hormone receptor-positive breast cancers that are between stages 1 and 3. Hormone receptor-positive breast cancer refers to breast cancer that is driven by hormones, and oftentimes that hormone is estrogen. The ASCO has stated that hormone receptor-positive breast cancer is the most typical type of breast cancer on the planet.

The ASCO based their new guideline decisions on information from 5 studies that have been reviewed in depth since 2010. In the studies with the longest follow-up periods, researchers found that women who took Tamoxifen for 10 years lived longer than those who took the drug for only 5. Women who took Tamoxifen for the longer period also saw lower rates of cancer remission, and their breast cancer was less likely to develop in the other breast.

The updated guidelines were published in the May edition of the Journal of Clinical Oncology. Guideline update panel co-chair Dr. Jennifer Griggs also commented on the new guidelines. “It is important for clinicians and patients to discuss the trade-offs between potential risks of side effects and potential benefits of taking adjuvant endocrine therapy for up to 10 years,” said Griggs. “Many women taking adjuvant tamoxifen experience side effects, and these appear to persist with longer duration. However, the trials did not find any new or unexpected side effects.”