Evaluation of the Effect of Cumulative Cisplatin Dose in Locoregionally Advanced Nasopharyngeal Carcinoma Patients Receiving Intensity-Modulated Radiotherapy

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Background: In nasopharyngeal carcinoma (NPC), the cut-off value of cumulative cisplatin dose (CCD) associated with survival benefits remains controversial. This study aimed to determine a CCD cut-off value for favorable survival outcomes and to identify specific patient groups benefitting from higher CCDs. Methods: We retrospectively reviewed the records of 161 patients (male-to-female ratio of 2.6:1.0) with NPC receiving concurrent chemoradiotherapy ± adjuvant chemotherapy (AC) from February 2006 through September 2015 at our referral center. The CCD was calculated for each patient, and 3-year locoregional-free survival (LRFS), distant-metastasis free survival (DMFS), disease-specific survival (DSS), and overall survival (OS) were analyzed using a multivariable Cox regression model. Results: Stage N3 patients and stage IV patients had lower DMFS, DSS, and OS. A CCD ≥ 200 mg/m 2 or AC was not associated with survival benefits. After adjusting for other factors, N3 status remained robustly correlated with DMFS ( p < 0.001) and DSS ( p = 0.001). In subgroup analyses, stage N3 patients treated with CCD ≥ 200 mg/m 2 exhibited evident trends toward higher OS (one-sided p = 0.062), DSS (one-sided p = 0.100), DMFS (one-sided p = 0.059), and LRFS (one-sided p = 0.059) than patients treated with CCD < 200 mg/m 2 . Conclusions: A CCD ≥ 200 mg/m 2 might result in better survival outcomes in stage N3 patients. Larger CCDs may be exclusively used in cases of regionally advanced disease to avoid rigorous toxicity.