Leucopenia and treatment efficacy in advanced nasopharyngeal carcinoma

Leucopenia or neutropenia during chemotherapy predicts better survival in several cancers. We aimed to assess whether leucopenia could be a biological measure of treatment and a marker of efficacy in advanced nasopharyngeal carcinoma (ANPC). We retrospectively analyzed 3826 patients with ANPC who received chemoradiotherapy. Leucopenia was categorised on the basis of worst grade during treatment according to the National Cancer Institute Common Toxicity Criteria version 4.0: no leucopenia (grade 0), mild leucopenia (grade 1–2), and severe leucopenia (grade 3–4). Associations between leucopenia and survival were estimated by Cox proportional hazards model. Of the 3826 patients, 2511 (65.6 %) developed mild leucopenia (grade 1–2) and 807 (21.1 %) developed severe leucopenia (grade 3–4) during treatment; 508 (13.3 %) did not. A multivariate Cox model that included leucopenia determined that the hazard ratios (HR) of death for patients with mild and severe leucopenia were 0.69 [95 % confidence interval (95 %CI) 0.56-0.85, p < 0.001] and 0.75 (95 %CI 0.59-0.95, p = 0.019), respectively; the HR of distant metastasis for patients with mild and severe leucopenia were 0.77 (95 %CI 0.61-0.96, p = 0.023) and 0.99 (95 %CI 0.77-1.29, p = 0.995), respectively. Leucopenia had no effect on locoregional relapse. Our results indicate that mild leucopenia during chemoradiotherapy is associated with improved overall survival and distant metastasis–free survival in ANPC. Mild leucopenia may indicate appropriate dosage of chemotherapy. We can identify the patients who may benefit from chemotherapy if they experienced leucopenia during the treatment. Prospective trials are required to assess whether dosing adjustments based on leucopenia may improve chemotherapy efficacy