Effect of leukocyte alteration on treatment outcomes following preoperative chemoradiotherapy in patients with rectal cancer.

Purpose: Hematotoxicity following anti-cancer treatment is known to be related to treatment efficacy in several malignancies. The purpose of this study was to examine the hematologic parameters related to the tumor response and survival in patients treated with curative surgery following preoperative chemoradiotherapy (CRT) for rectal cancer. Materials and Methods: Four hundred eighteen patients with rectal cancer who underwent preoperative CRT and curative surgery were analyzed, retrospectively. The main clinical factors and blood cell counts before and after CRT were investigated with respect to their relationships with tumor downstaging and patient survival. Results: The post-CRT leukocyte count was significantly different between the tumor downstaging group and the nondownstaging group (median, 4740/uL vs. 5130/uL; p = 0.013). Multivariate analysis showed that histological grade, circumferential extent, and post-CRT leukocyte count were related to tumor downstaging. In addition, histological grade, post-CRT leukocyte count, and tumor downstaging were related to disease-free survival. The 5-year disease-free survival and overall survival in patients with post-CRT leukocyte count ≤3730/uL, which is the cut-off value derived from the receiver operation characteristic (ROC) curve analysis, were significantly higher than those with higher counts (88.0% vs. 71.6%, p = 0.001; 94.4% vs. 84.1%, p = 0.024). Conclusion: Post-CRT leukocyte count of ≤3730/uL could be regarded as a good prognostic factor for tumor response and survival in rectal cancer patients treated with preoperative CRT. [ABSTRACT FROM AUTHOR]