First results from the RxPONDER trial suggest postmenopausal women with HR+, HER2- breast cancer with one to three positive nodes and a recurrence score of 25 or lower can safely skip adjuvant chemotherapy.
The international trial, presented at the virtual 2020 San Antonio Breast Cancer Symposium, comprised 5,083 patients with stage 2-3 breast cancer randomised to endocrine therapy alone or endocrine therapy plus chemotherapy. About two-thirds of the participants were postmenopausal.
Dr Kevin Kalinsky, director of the Glenn Family Breast Centre at Winship Cancer Institute, Emory University (US), said while chemotherapy was generally recommended for medically eligible patients, the study found no apparent benefit from the addition of chemotherapy after a median follow-up of 5.1 years for some women.
The study found five-year invasive disease-free survival (IDFS) was similar in postmenopausal women regardless of whether or not they received chemotherapy (91.6 % v. 91.9%; HR 0.97; p=0.82).
However in premenopausal patients, five-year IDFS was 94.2% for those who received chemotherapy compared to 89% for those who did not receive chemotherapy (HR 0.54; p=0.0004).
“At the time of this analysis, our data show that postmenopausal women with HR-positive, HER2-negative breast cancer with one to three positive nodes and a recurrence score of 25 or lower can safely avoid receiving adjuvant chemotherapy.”
“Up until now, there were no data from a large randomised clinical trial to guide this decision,” he said.
“On the other hand, premenopausal patients with HR-positive, HER2-negative breast cancer with one to three positive nodes and a recurrence score of 25 or lower should consider adjuvant chemotherapy. The invasive disease-free survival rate improved by 5% with chemotherapy in this group,” Dr Kalinsky said.
“We have also identified an overall survival improvement at five years with the addition of chemotherapy in premenopausal women.”
He said the finding will save tens of thousands of women from the time, expense and potentially harmful side effects that can be associated with chemotherapy infusions.
Commenting on the study, Dr Kent Osbourne from Baylor College of Medicine in Houston, said in the press conference that the results clearly showed no benefit from adding chemotherapy to standard endocrine therapy in postmenopausal women even with node positivity.
“Node positivity, while an important prognostic marker, is not a predictive marker of chemotherapy sensitivity.”
Disclosure statement: Dr Kalinsky reports research support from Immunomedics Inc., Novartis, Incyte, Genentech/Roche, EliLilly, Pfizer, Calithera Biosciences, Acetylon, Seattle Genetics, Amgen, Zentalis Pharmaceuticals, and CytomXTherapeutics; has served as a consultant to Immunomedics, Biotheranostics, Pfizer, Novartis, Eisai, EliLilly, Amgen, Merck, Seattle Genetics, and AstraZeneca.