ASCO Recommends Ovarian Suppression for ER-Positive Breast Cancer

An American Society of Clinical Oncology (ASCO) expert panel issued an updated guideline recommending that higher-risk premenopausal women with estrogen receptor (ER)-positive breast cancer receive ovarian suppression in addition to adjuvant endocrine therapy. Lower-risk patients, however, should not receive ovarian suppression.

“In the past year, randomized trials with robust methodological designs have analyzed the effect of ovarian suppression among premenopausal women with ER-positive breast cancers treated with tamoxifen,” wrote the panel, led by ASCO expert Harold J. Burstein, MD, PhD, of Dana-Farber Cancer Institute in Boston. In the past, studies of this therapy have suffered from problems such as selection criteria confounding.

The guideline update is based on four randomized controlled trials. These include the Eastern Cooperative Oncology Group 3193 (E-3193) trial, the Suppression of Ovarian Function Trial (SOFT), the Tamoxifen and Exemestane Trial (TEXT), and the Austrian Breast Cancer Study Group (ABCSG)-12 trial. Overall, the studies did not find a significant difference with regard to overall survival between tamoxifen alone, tamoxifen plus ovarian suppression, or aromatase inhibitors (AIs) plus ovarian suppression. The guideline update was published in the Journal of Clinical Oncology.

In some cases, the trials did show an improvement in disease-free survival (DFS) or freedom from recurrence. After a median follow-up of 67 months, the SOFT trial found that ovarian suppression with AI therapy reduced the risk of recurrence compared with tamoxifen alone; this was true even after adjustment for a number of factors.

Furthermore, for the “large clinical subset” of SOFT patients who were at high enough risk for recurrence that adjuvant or neoadjuvant chemotherapy was administered, the addition of ovarian suppression did improve DFS significantly, as well as freedom from breast cancer and distant recurrence.

The addition of ovarian suppression to therapy did increase adverse events and worsened quality of life. In the E-3193, SOFT, and TEXT trials, women receiving ovarian suppression and tamoxifen reported more menopausal symptoms, diminished sexual function, and impaired overall health-related quality of life. Those receiving AIs plus ovarian suppression reported a slightly different set of effects than those receiving tamoxifen and ovarian suppression; in both cases, the symptoms persisted over the 5-year course of treatment.

“In general, if the risk of recurrence despite tamoxifen was sufficient to warrant consideration of chemotherapy, then the Panel believed that patient should receive ovarian suppression,” they wrote. In women on the other end of the risk spectrum, however, they noted that “there was no demonstrable benefit to ovarian suppression treatment.” They also noted that there is no current role for ovarian suppression in ER-negative breast cancers.