Premenopausal women benefit from adjuvant chemotherapy next to endocrine therapy

The phase 3 RxPONDER trial evaluated the benefit of adjuvant chemotherapy followed by endocrine therapy in women with hormone receptor (HR)-positive/HER2-negative, early-stage breast cancer and 1–3 positive nodes. Updated results confirmed that the menopausal status makes the difference in this population.

The RxPONDER trial (NCT01272037) evaluated the benefit of chemotherapy followed by endocrine therapy versus endocrine therapy alone in patients who had an Oncotype DX Recurrence Score (RS) <25. A previous analysis of RxPONDER after a median follow-up of 5 years reported that invasive disease-free survival (IDFS) and distant disease-free survival (DDFS) differed by menopausal status [1]. In the current study, Dr Kevin Kalinsky (Emory University Winship Cancer Institute, GA, USA) reported updates on IDFS and DDFS with follow-up of 6.1 years, as well as distant recurrence-free intervals (DRFI), and post-hoc analyses in premenopausal women. DRFI was defined as time to distant recurrence or death from breast cancer [2].

Consistent with the results from the previous analysis, postmenopausal women continued to not have any IDFS or DDFS benefit with adjuvant chemotherapy, whereas premenopausal women continued to benefit from adjuvant chemotherapy, with a 5-year absolute benefit for IDFS and DDFS of 4.9% and 2.5%, respectively. In line with these results, chemotherapy improved in premenopausal patients (absolute 5-year benefit 2.4%) and not in postmenopausal patients. In premenopausal patients with RS 0–13, the absolute benefit was 2.3%; in premenopausal patients with RS 14–25, the benefit was 2.8%.

Among the premenopausal patients, 12.4% had micro-metastatic disease. Post-hoc analysis showed a trend for chemotherapy benefit for those with micro-metastatic disease (HR 0.44, absolute 5-year benefit 7.3%). However, only 22 IDFS events were present. In premenopausal patients (1,403) with macro-metastases (pN1), the absolute 5-year benefit of chemotherapy was 4.8%.

“This update of RxPONDER confirms that postmenopausal women with RS<25 do not benefit from adjuvant chemotherapy,” concluded Dr Kalinsky. “In addition, premenopausal women with RS<25 continue to benefit from adjuvant chemotherapy resulting in a 44–46% decrease in IDFS, DRFS, and DRFS events.”

1. Kalinsky K, et al. N Eng J Med 2021;385(25):2336–2347.
2. Kalinsky KM, et al. Updated results from a phase 3 randomized clinical trial in participants (pts) with 1-3 positive lymph nodes (LN), hormone receptor-positive (HR+) and HER2-negative (HER2-) breast cancer (BC) with recurrence score (RS) < 25 randomized to endocrine therapy (ET) +/- chemotherapy (CT): SWOG S1007 (RxPONDER). GS2-07, SABCS 2021 Virtual Meeting, 7–10 December.

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Posted on 31 January, 2022