Commenting on the update of RxPONDER presented at the 2021 San Antonio Breast Cancer Symposium were Anne Blaes, MD, MS, Associate Professor of Hematology/Oncology at the University of Minnesota and Co-Director of the Screening, Prevention, Etiology and Cancer Survivorship Program at the Masonic Cancer Center, Minneapolis, and Virginia Kaklamani, MD, Professor of Medicine at The University of Texas Health Sciences Center San Antonio and leader of the breast cancer program at the Mays Cancer Center, San Antonio.
Anne Blaes, MD, MS
Virginia Kaklamani, MD
Dr. Blaes, the study’s invited discussant, noted that in the update, premenopausal women had a 2.4% absolute benefit in 5-year disease recurrence–free interval with chemotherapy. This benefit was seen both in patients with micrometastases and in N1 disease. For N1 disease, the 5-year invasive disease–free survival benefit was 4.8%, she noted, “arguing that many of these premenopausal women with one to three positive nodes do benefit from chemotherapy,” especially those with a recurrence score (RS) of 11 to 25.
The study also found a nearly equivalent benefit for both treatments in women with suppressed menstrual periods, as compared with those who still had regular periods. “This raises the question of whether the benefit in the chemotherapy arm relates to the chemotherapy itself or is a result of ovarian function suppression. This question remains,” she said.
Dr. Blaes’ takeaway from the update was this: using genomic platforms to risk-stratify the role of chemotherapy shows that premenopausal women with node-positive disease and an RS between 11 and 25 may benefit from chemotherapy, “though further work should explore ovarian function suppression as a therapeutic option over chemotherapy.”
‘Focus on the Data We Have’
In an interview with The ASCO Post, Dr. Kaklamani said the findings were largely confirmatory of earlier data, but they also shed more light on one of the essential questions the study has provoked: whether chemotherapy might be equivalent to ovarian function suppression.
“I was using the data from last year’s analysis to warrant giving chemotherapy to premenopausal women, regardless of recurrence score. Subsequent to the presentation of those earlier data, many of us began discussing whether for some lower-risk women, we could get away from chemotherapy by using ovarian function suppression,” she said. Based on the update and exploratory analyses presented at this meeting, she has concluded: “We should focus on the data we have that say chemotherapy is what we should use.”
She also noted that although ovarian function suppression may sound more appealing than chemotherapy, to patients, it has its own drawback: “You have to give ovarian suppression for 5 years, and how many women can really tolerate that? Although chemotherapy might be rough, you only have to give it for 3 months,” she tells patients.
DISCLOSURE: Dr. Blaes reported no conflicts of interest. Dr. Kaklamani has served as a consultant or speaker for Pfizer, Celgene, Genentech, Genomic Health, Puma, Eisai, Novartis, AstraZeneca, Daiichi Sankyo, Seattle Genetics, Puma, AstraZeneca, Athenex, and Immunomedics.
Updated results of the SWOG S1007 RxPONDER trial confirmed the key takeaway from the previous analysis: adjuvant chemotherapy benefits premenopausal women but not postmenopausal women with hormone receptor–positive, HER2-negative disease, one to three positive lymph nodes, and a 21-gene Oncotype DX ...