Poor Prognostic Effects of Lymphocytopenia Induced by Preoperative Chemoradiotherapy in Rectal Cancer

We evaluated the prognostic effect of lymphocytopenia caused by preoperative radiation therapy and chemotherapy in patients with rectal cancer.

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.

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).

Lymphocytopenia induced by preoperative chemoradiotherapy is associated with lower DFS in patients with rectal cancer. Efforts to avoid lymphocytopenia may help prevent cancer recurrence.