The correlation of neutrophil/lymphocyte ratio and tumor reduction ratio in preoperative chermoradiotherapy for advanced rectal cancer.

Abstract

633 Background: Preoperative chemoradiotherapy (CRT) is widely used for the treatment of advanced lower rectal cancer and is considered to reduce the local recurrence rate and improve the anus preservation rate. However, the tumor reduction effect varies among patients, and thus far, no factor has yet been found to be effective in the prediction of therapeutic efficacy. Recent studies have shown tumor immunity in the tumor microenvironment to be involved in the anti-tumor effect of radiation and anti-cancer drugs. Among these studies, some show that the neutrophil/lymphocyte (NL) ratio in blood test results correlates with the therapeutic efficacy. We examined the correlation between the NL ratio based on blood test results and tumor-reducing effect of preoperative CRT on advanced lower rectal cancers. Methods: We included 30 advanced lower rectal cancer patients who underwent preoperative CRT during the period ranging from January 2008 to June 2013.For advanced lower rectal cancers classified as cT3orT4NXM0, preoperative CRT was conducted according to the following regimen: 50.4 Gy (1.8 Gy × 28 fr) + UFT (300 mg/day, LV [75 mg/day]) × 28 days. The neutrophil count and lymphocyte count were determined based on the blood tests conducted before and after CRT; the NL ratio was calculated, and the correlation between the value of the ratio and tumor reduction rate was examined. Results: Radical surgery was performed on 28 of the 30 patients who underwent preoperative CRT. One of the 28 patients showed local recurrence (rate, 3.6%). In addition, down stage tumors were found in 16 of the 28 patients, and the down stage rate was 57.1%. Significant differences (p < 0.0001) were found between the tumor reduction effect and NL ratio from blood tests before CRT, as well as between the tumor reduction effect and the ratio from blood tests after CRT. Conclusions: The above findings suggest anti-tumor immunity in the tumor microenvironment, particularly that lymphocytes might be involved in the antitumor effectiveness of preoperative CRT in advanced lower rectal cancers. In addition, NL ratio from blood tests could be a predictive factor of the tumor reduction effect.