Thrombocytosis before pre-operative chemoradiotherapy predicts poor response and shorter local recurrence-free survival in rectal cancer

Purpose Although thrombocytosis has been reported in patients with various cancers including the colorectal one, the impact of elevated platelet counts on the response to chemoradiotherapy (CRT) for rectal cancer has not been fully investigated. We investigated the clinical significance of pre- and post-CRT platelet counts in patients with rectal cancer. Methods The medical records of 101 patients with rectal cancer, who had received CRT followed by surgical resection, were retrospectively reviewed. The correlations between the clinicopathological variables and the pre- or post-CRT platelet counts were analyzed. The correlations between tumor regression rate induced by CRT, as evaluated by barium enema and pathological examination, and the pre- or post-CRT platelet counts were also evaluated. Finally, the impact of pre-CRT thrombocytosis on the prognosis of these patients was assessed. Results The pre-CRT platelet count correlated with venous invasion and tumor size, and it strongly correlated with the response rate evaluated by barium enema and the grade of pathological tumor regression. Furthermore, patients with pre-CRT thrombocytosis had significantly shorter local recurrence-free survival. Conclusion Platelet count before CRT should be a promising biomarker for predicting the efficacy of CRT and the risk of local recurrence in rectal cancer patients after CRT.