Adjuvant Chemotherapy Guided by a 21-Gene Expression Assay in Breast Cancer

Sparano JA, Gray RJ, Makower DF, et al. N Engl J Med. N Engl J Med. 2018; June 3. [CrossRef]

There is uncertainty about the benefit of chemotherapy in most breast cancer. The authors performed a prospective trial involving 10,273 women with hormone-receptor–positive, human epidermal growth factor receptor 2 (HER2)–negative, axillary node–negative breast cancer. Of the 9719 eligible patients with follow-up information, 6711 (69%) had an indeterminate risk for recurrence and were randomly assigned to receive either chemoendocrine therapy or endocrine therapy alone. Endocrine therapy was noninferior to chemoendocrine therapy in the analysis of invasive disease–free survival (hazard ratio for invasive disease recurrence, second primary cancer, or death [endocrine vs. chemoendocrine therapy], 1.08; 95% confidence interval, 0.94 to 1.24; P=0.26). At 9 years, the two treatment groups had similar rates of invasive disease–free survival (83.3% in the endocrine-therapy group and 84.3% in the chemoendocrine-therapy group), freedom from disease recurrence at a distant site (94.5% and 95.0%) or at a distant or local–regional site (92.2% and 92.9%), and overall survival (93.9% and 93.8%). However, there was some benefit of chemotherapy found in women 50 years of age or younger. The authors conclude that addition of chemotherapy had no advantage for most women with hormone-receptor–positive, HER2-negative, axillary node–negative breast cancer, although some benefit of chemotherapy was found in some women 50 years of age or younger.