Individualized cumulative cisplatin dose for locoregionally-advanced nasopharyngeal carcinoma patients receiving induction chemotherapy and concurrent chemoradiotherapy

Objectives: To screen subgroup potentially benefiting from cumulative cisplatin dose (CCD) >= 200 mg/m(2) during concurrent chemoradiotherapy (CCRT) of patients with locoregionally-advanced nasopharyngeal carcinoma (LA-NPC) receiving induction chemotherapy (IC) and CCRT. Materials and Methods: In total, 2 063 patients with non-disseminated LA-NPC diagnosed from 2009 to 2015 receiving IC plus CCRT were enrolled. Patients were restaged based on proposed stage groupings and risk groupings was established. After propensity score matching, survival outcomes were compared within different risk groupings with 200 mg/m2 CCD. Post-IC gross primary tumor (GTVp) and lymph node (GTVnd) volumes were calculated from planning computed tomography. The role of risk groupings and post-IC tumor volume to CCD was explored. Results: Compared with the low-risk group, the high-risk group showed poor survival outcomes in terms of 5-year progression-free survival (PFS), overall survival (OS), distant metastasis-free survival (DMFS), and locoregional relapse-free survival (LRRFS). CCD >= 200 mg/m2 improved survival in terms of 5-year PFS, OS and DMFS in the high-risk group but not in the low-risk group. High-risk patients with unfavorable response to IC benefited from CCD >= 200 mg/m(2) with respect to PFS and DMFS; while those in low-risk group or with favorable response to IC didn't. Conclusions: Risk groupings was effective for risk stratification. Combining risk groupings and post-IC tumor volume is a simple and useful method to guide individualized CCD treatment of CCRT for patients with LA-NPC receiving IC and CCRT. CCD >= 200 mg/m(2) may be indicated for high-risk patients with unfavorable response to IC.