3. Pregnancy risks
Can endocrine therapy be safely interrupted for women with breast cancer who wish to become pregnant? That’s what researchers tried to glean in a recent prospective trial presented at the meeting (GS4-09).
The study enrolled over 500 women for whom endocrine therapy had been stopped in the hopes of their becoming pregnant. Almost all (93.4%) had stage I/II HR-positive breast cancer. The primary objective was to determine the risk of breast cancer relapse associated with interrupting therapy for about 2 years. The authors defined no more than 46 breast cancer–free interval (BCFI) events as the safety threshold. A BCFI event was defined as local, regional, or distant recurrence or a new invasive contralateral breast cancer.
Among 497 women, 368 (74%) had at least one pregnancy and 317 (64%) had at least one live birth, for a total of 365 babies born. At a median follow-up of 41 months, 44 participants experienced a BCFI event, in line with the safety threshold. The 3-year BCFI failure rate was 8.9%, similar to the 9.2% rate in an external control cohort from the SOFT/TEXT trials. In addition, 76.3% of patients resumed endocrine therapy; 15.4% had not yet resumed therapy.
“This trial is more confirmatory but an extremely important step for young women who want to get pregnant after diagnosis and recovery from HR-positive breast cancer,” Dr. Kaklamani said. “It seems that stopping endocrine therapy to become pregnant did not cause any adverse outcomes or increase the risk of reoccurrence of cancer in the women in the study.”
Dr. Mouabbi agreed, noting, “Many of our patients are afraid that they will miss the window to get pregnant because they have to be on treatment for so long. This is the first study that let us know pregnancy and safety outcomes in patients who took a break from endocrine therapy to get pregnant. The results are promising and will be exciting for many of our patients.”
4. Assay identifies OFS benefit
A genomic assay was able to distinguish premenopausal patients with early-stage HR-positive breast cancer who benefited from the addition of ovarian function suppression (OFS) to adjuvant endocrine therapy, according to new data presented at the meeting (GS1-06).
In the study, investigators analyzed 1,717 patient tumor samples from the landmark Suppression of Ovarian Function Trial (SOFT) trial. The Breast Cancer Index identified 58% of women who benefited from the addition of ovarian function suppression to tamoxifen or exemestane therapy. They experienced an absolute benefit of 11.6% (42% did not benefit), compared with those with received tamoxifen alone. The predictive benefit was observed regardless of age, lymph node involvement, and receipt of chemotherapy.
Dr. Kaklamani highlighted this study’s importance, saying, “Ovarian suppression is associated with severe adverse events for patients. Obviously, the women who will get a benefit should continue, but this research is important because it will hopefully show us who to recommend ovarian suppression to while not exposing patients who are likely to get little benefit to unneeded toxicity.”