Certain postmenopausal patients with breast cancer can avoid chemotherapy, study shows

Certain post-menopausal women with HR-positive, HER2-negative breast cancer may be able to only undergo endocrine therapy after surgery – sparing themselves from the chemotherapy side effects.

Certain patients with HR-positive, HER2-negative breast cancer can safely opt to skip chemotherapy treatment and instead just take endocrine therapy after surgery, according to recent study results published in the New England Journal of Medicine.

Results from S1007, the RxPONDER study, showed that post-menopausal women with HR-positive, HER2-negative breast cancer that has spread to three or fewer lymph nodes and has a 21-gene recurrence score of 25 or lower had no significant difference in invasive disease-free survival at five years when they had post-surgical endocrine therapy compared with those who had endocrine therapy and chemotherapy after surgery.

“In medicine, sometimes we add (treatments) on, but it’s also important to think about giving treatments when you really need them. We saw that these patients did not benefit from chemo,” said Dr. Kevin Kalinsky, lead investigator in RxPONDER and associate professor of Medicine at the Winship Cancer Institute at Emory University, in an interview with CURE®. Kalinsky explained that by avoiding unnecessary chemotherapy, patients can spare themselves both short- and long-term side effects associated with the treatment.

Although post-menopausal women had no added benefit from chemotherapy, this was not the case for pre-menopausal women – who made up about one-third of the patients enrolled in the trial.

In the group of women who have not yet gone through menopause, a 40% relative invasive disease-free survival benefit was seen in those who had chemotherapy plus endocrine therapy compared with pre-menopausal women who had endocrine therapy alone. This was true even for patients with low recurrence scores.

“There are a number of questions that have been derived out of this study,” Kalinsky said. “Is that benefit exclusively due to the fact that some patients stop having regular periods? Or is there a difference in the biology of the cancer between the pre- and post-menopausal patients? So we’re undergoing a large effort now to look at the tumors in patients who are pre-menopausal to see if we can help identify if there are any biologic differences. That may explain why we’re seeing this differential benefit based on menopausal status.”

All of this research is geared toward personalized treatment plans that improve outcomes and step away from the one-size-fits-all cancer treatment model. Patients can play a role in this shift, too, by talking to their clinicians about their individual risks and undergoing genomic testing, like the 21-gene assay used in this particular study.

“When those results come back, talk to your provider – (regardless) if you’re pre-menopausal or post-menopausal – about the benefits of chemotherapy or not (getting it),” Kalinsky said, noting that study results like these will hopefully make patients feel more confident in foregoing chemotherapy if it may not benefit them.

“Every conversation is an individualized conversation with the patient that’s in front of you in terms of the risks and benefits that they are willing or not willing to accept to decrease risk. These data help inform that one-on-one conversation,” Kalinsky said.

This article was originally published on Cure®.