Concurrent or sequential letrozole with adjuvant breast radiotherapy

We have read with interest the final results of the CO-HO-RT phase II trial, recently published by Bourgier and colleagues (1). In brief, 150 patients affected by stage I-II breast cancer (BC) were randomized to receive either concomitant or sequential letrozole and adjuvant radiotherapy (RT) after breast conservative surgery. Furthermore, 121 patients were tested for radio-induced lymphocyte apoptosis (RILA), and single nucleotide polymorphisms (SNP) related to radio-induced subcutaneous fibrosis (RISF). Authors did not find differences in terms of safety between concomitant or sequential letrozole and RT, but translational sub-analysis identified a correlation between RILA and RISF, with a significantly lower value of RILA in patients with RISF grade ≥2 compared to RISF ≤1 (6.9% vs. 13%; P=0.02). Moreover, two SNP located within phosphatase and actin regulatory protein 3 (PHACT3) gene resulted significantly associated with RILA.