The Cumulative Cisplatin Dose Affects the Long-Term Survival Outcomes of Patients with Nasopharyngeal Carcinoma Receiving Concurrent Chemoradiotherapy

The prognostic value of the cumulative cisplatin dose (CCD) remains controversial for patients with nasopharyngeal carcinoma (NPC) receiving only concurrent chemoradiotherapy (CCRT). We retrospectively reviewed 549 consecutive patients with non-metastatic, histologically-proven NPC treated using intensity-modulated radiotherapy (IMRT) at Sun Yat-sen university cancer center. Patient survival between different CCD groups were compared. The cut-off value of pre-treatment plasma EBV DNA (pre-DNA) and CCD based on disease-free survival (DFS) were 1460 copies/ml (AUC, 0.691; sensitivity, 0.717; specificity, 0.635) and 240 mg/m(2) (AUC, 0.506; sensitivity, 0.526; specificity, 0.538), respectively. Of the entire cohort, 92/549 (16.8%) patients received a CCD ≥ 240 mg/m(2) and 457 (83.2%) patients, <240 mg/m(2). For CCD ≥ 240 mg/m(2) vs. < 240 mg/m(2), the estimated 4-year DFS, overall survival (OS), locoregional-free survival (LRFFS) and distant metastasis-free survival (DMFS) rates were 89.1% vs. 81.3% (P = 0.097), 92.4% vs. 90.0% (P = 0.369), 95.6% vs. 91.2% (P = 0.156), and 91.3% vs. 88.4% (P = 0.375), respectively. For the whole cohort, multivariate analysis identified the CCD was an independent prognostic factor for DFS (HR, 0.515; 95% CI, 0.267–0.995; P = 0.048). However, CCD (≥240 mg/m(2)) had no prognostic value in subgroup analysis with stratification by the cut-off value of pre-DNA (P > 0.05 for all rates).