Kalinsky K, Barlow WE, Gralow JR, et al. - In this study, chemoendocrine therapy for breast cancer conferred longer invasive disease–free survival and distant relapse–free survival, vs endocrine-only therapy, in premenopausal women with one to three positive lymph nodes and a recurrence score of 25 or lower. Adjuvant chemotherapy failed to be beneficial for postmenopausal women with similar characteristics.

• A prospective trial wherein 5,083 women (33.2% premenopausal and 66.8% postmenopausal) with hormone-receptor–positive, human epidermal growth factor receptor 2-negative breast cancer, one to three positive axillary lymph nodes, and a recurrence score of 25 or lower were included.

• They were randomized to endocrine therapy only or to chemotherapy plus endocrine (chemoendocrine) therapy.

• In interim analysis, difference in chemotherapy benefit, in terms of increasing invasive disease–free survival, was evident by menopausal status (P=0.008 for the comparison of chemotherapy benefit in premenopausal and postmenopausal participants).

• At 5 years, postmenopausal women in the endocrine-only group showed an invasive disease–free survival of 91.9%, and those from the chemoendocrine group 91.3%, with no chemotherapy benefit (hazard ratio for invasive disease recurrence, new primary cancer, or death, 1.02).

• In premenopausal group, endocrine-only therapy conferred an invasive disease–free survival of 89.0% vs 93.9% with chemoendocrine therapy, at 5 years (hazard ratio, 0.60), with a similar increase in distant relapse–free survival (hazard ratio, 0.58).

• With increasing recurrence score, no increase was seen in the relative chemotherapy benefit.