Postmenopausal women with 1 to 3 positive nodes and a recurrence score of ≤25 can avoid adjuvant chemotherapy without negative impact on invasive disease-free survival.

The prior TAILORx trial (NEJM JW Oncol Hematol Jul 2018 and N Engl J Med 2018; 379:111) showed that 21-gene recurrence score (RS) intermediate results (11–25) could be used to identify patients with estrogen-receptor (ER)-positive, node-negative breast cancer who could avoid adjuvant chemotherapy without any detrimental impact on outcome. Now, to provide similar guidance for patients with ER-positive, node-positive disease, investigators conducted a prospective, multicenter, randomized trial (RxPONDER), sponsored by the National Cancer Institute Cancer Therapy Evaluation Program.

The trial involved 5018 women (67% postmenopausal) from 632 sites in nine countries with ER-positive and HER2-negative, early-stage breast cancer with 1 to 3 involved axillary lymph nodes and an RS of ≤25. Participants were assigned to endocrine therapy with or without chemotherapy. Stratification factors included RS (0–13 or 14–25), menopausal status, and type of axillary surgery (sentinel-node biopsy or axillary lymph-node dissection).

Results at a median follow-up of 5 years were as follows:

• Among postmenopausal women, invasive disease-free survival (iDFS; the primary objective) was similar with endocrine-only therapy or chemo-endocrine therapy (91.9% and 91.3%, respectively); no subgroup gained benefit from chemotherapy.
• Among premenopausal women, iDFS was improved with chemo-endocrine therapy versus endocrine-only therapy (93.9% vs. 89.0%; hazard ratio, 0.60; P=0.002)
• No chemotherapy benefit was observed in premenopausal women age ≥50 years; those age <50 years did achieve a benefit (HR, 0.48).
• The chemotherapy benefit for premenopausal women remained significant (HR, 0.60), after adjustment for age, number of positive nodes, tumor grade, and tumor size; the benefit did not increase as RS increased.

Comment

The RxPONDER trial showed that postmenopausal women with ER-positive and HER2-negative, early-stage breast cancer with 1 to 3 involved axillary lymph nodes and an RS of ≤25 achieved similar outcomes with adjuvant endocrine therapy with or without chemotherapy. However, premenopausal women can continue to derive clinically meaningful benefit from the addition of chemotherapy to adjuvant endocrine therapy.

Source: NEJM