Abstract
BACKGROUND: We evaluated the prognostic effect of lymphocytopenia caused by preoperative radiation therapy and chemotherapy in patients with rectal cancer. METHODS: A total of 147 patients with rectal cancer who underwent preoperative chemoradiotherapy and surgical resection between 2008 to 2021 participated. Lymphocyte nadir less than 500/μl were defined as lymphocytopenia in this study. The relationship between lymphocyte nadir after chemoradiotherapy and disease-free survival (DFS) was evaluated. RESULTS: Median follow-up was 60.7 months. A total of 21 patients (14.3%) showed lymphocytopenia related to preoperative chemoradiotherapy. Out of the original 147 patients, 29 (19.7%) patients had a diagnosis of diabetes mellitus, and 66 (44.9%) patients were overweight (body mass index exceeding 23). Lymphocytopenia occurred frequently in non-diabetic patients (p = 0.006) and non-overweight patients (p = 0.001). The pathologic complete response (pCR, n = 19) rate after chemoradiotherapy tended to be positively correlated with body mass index (p = 0.09). Lymphocytopenia was associated with lower DFS (p = 0.009). However, overall survival and intra-pelvic relapse-free survival were not associated with lymphocytopenia (p = 0.124 and p = 0.156). CONCLUSIONS: Lymphocytopenia induced by preoperative chemoradiotherapy is associated with lower DFS in patients with rectal cancer. Efforts to avoid lymphocytopenia may help prevent cancer recurrence.