To the editor,


I wish to congratulate Zeidman and their colleagues [1] for their article in which they explored utility of neoadjuvant chemotherapy (NAC) for hormone receptor-positive HER2-negative (HR+ HER2−) patients. Among 134,574 patients, 105,324 (78%) had adjuvant chemotherapy (AC) and 29,250 (22%) received NAC. They found that NAC use among HR+ HER2− breast cancer patients has expanded over time and offers downstaging of disease for some patients, with pCR seen in only a small subset (8.3%), but downstaging of the axilla in 21%. They concluded that more studies are needed to explore these findings and better predict patients who would be excellent responders. The authors did not analyze response rates of patients according to luminal subtypes. The St. Gallen International Expert Consensus 2013 defined luminal A as ER-positive, HER2-negative, Ki-67 low, and PR high and Luminal B as ER-positive, HER2-negative, and either Ki-67 high or PR low [2]. Haque et al. [3] analyzed response rates and pCR by breast cancer molecular subtype following NAC. Among ER-positive breast cancer patients, 322 (2%) cases and 5941 (43%) cases were luminal A and luminal B. Compared with luminal A, luminal B was nearly 30 times more likely to achieve pCR. Interestingly, the overall pCR rate was only 0.3% in luminal A disease. Taken all together, luminal subtype B might be better predictive marker showing greater response to NAC. This issue merits further investigation.