Correlation between treatment-related lymphopenia and pathologic response in esophageal squamous cell carcinoma patients undergoing neoadjuvant chemoradiotherapy

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Objective To investigate the relationship between treatment-related lymphopenia and pathologic complete response (pCR) to neoadjuvant chemoradiotherapy (CRT) in patients with esophageal squamous cell carcinoma (ESCC). Methods Clinical data of 220 ESCC patients treated with neoadjuvant CRT followed by surgery between 2002 and 2016 were retrospectively analyzed. Absolute lymphocyte count was determined before and at 1 month after neoadjuvant CRT. Treatment-related lymphopenia was graded using Common Terminology Criteria for Adverse Events (CTCAE, 4.0 version). The relationship between lymphopenia, pCR and recurrence was evaluated by chi-square test and Cox’s regression model. Results Ninety-five patients (43.2%) achieved a pCR after neoadjuvant CRT and 71 cases (32.3%) recurred postoperatively. During neoadjuvant CRT, the incidence rates of grade 0, 1, 2, 3, and 4 lymphopenia were 1.8%, 6.8%, 31.4%, 38.2%, and 21.8%, respectively. Patients with grade 4 lymphopenia had a significantly lower pCR rate than those with grade 0-3 lymphopenia (22.9% vs.48.8%, P=0.001). Moreover, grade 4 lymphopenia was significantly associated with a higher risk of recurrence (45.8% vs.28.5%, P=0.023). Multivariate analysis identified that primary tumor length, tumor location and radiation dose were the independent predictors for grade 4 lymphopenia during neoadjuvant CRT (P=0.013, 0.001, 0.002). Conclusions The incidence of grade 4 lymphopenia in ESCC patients undergoing neoadjuvant CRT is correlated with a low pCR rate and a high risk of recurrence. Lymphopenia can be used as an economic and effective predictor for pCR. Key words: Esophageal neoplasm/neoadjuvant chemoradiotherapy; Lymphopenia; Pathologic response