Absolute Lymphocyte Count in Preoperative Chemoradiotherapy for Rectal Cancer: Changes Over Time and Prognostic Significance

Abstract

We analyzed the changes in absolute lymphocyte count and its changes over time in 139 patients treated with preoperative chemoradiotherapy for locally advanced rectal cancer. The baseline absolute lymphocyte count was defined as the median of absolute lymphocyte count levels measured during 30 days before preoperative chemoradiotherapy. Absolute lymphocyte count at 1 month, 0.5 to 1 year, 1 to 2 years, and 2 to 3 years were determined by the median values of the absolute lymphocyte counts during the respective periods. Absolute lymphocyte count decreased after delivering preoperative chemoradiotherapy, reached minimum level at 1 month, and then gradually increased after the completion of chemoradiotherapy. Baseline absolute lymphocyte count had significant correlations with the absolute lymphocyte count of every period (range of coefficient, 0.41-0.64, P < .001). The overall survival of the group with high baseline absolute lymphocyte count was significantly higher than that of the group with low baseline absolute lymphocyte count (5-year overall survival: 82.4% vs 62.9%, P = .012). In multivariable analyses, the baseline absolute lymphocyte count remained as a significant prognostic factor for overall survival, favoring the group with a high baseline absolute lymphocyte count (hazard ratio = 0.405, P = .017). This study showed that the level of baseline absolute lymphocyte count was an independent prognostic factor, and it correlated with the absolute lymphocyte counts across varying periods of treatments and follow-up in patients treated with preoperative chemoradiotherapy for rectal adenocarcinoma.