Lee JH, et al. - In this multi-institutional analysis, researchers ascertained if change of white blood-cell (WBC) count before and during chemoradiotherapy (CRT) might be related to susceptibility to radiation and tumor response. In addition, they evaluated nadir/pre-CRT ratio of WBC count as a predictor for tumor response to CRT and a prognostic factor for recurrence-free survival. They retrospectively reviewed records of 641 subjects with rectal cancer who had preoperative CRT followed by curative surgery in five tertiary centers. During preoperative CRT, low nadir/pre-chemoradiotherapy ratio could predict good tumor response and was significantly related to improved recurrence-free survival in rectal cancer. Findings revealed that complete pathologic response rate after CRT was significantly higher in low WBC ratio arm than that in high WBC ratio arm.