Optimizing the cumulative cisplatin dose for concurrent chemoradiotherapy beneficiaries among elderly nasopharyngeal carcinoma patients: a real world study.

This study aimed to find a safe and effective cumulative cisplatin dose (CCD) for concurrent chemoradiotherapy (CCRT) beneficiaries among elderly nasopharyngeal carcinoma (NPC) patients. A total of 765 elderly (>/= 60 years old) NPC patients treated with cisplatin-based CCRT and IMRT-alone from 2007 to 2018 were included in this study. RPA-generated risk stratification was used to identify CCRT beneficiaries. CCDs were divided into CCD = 0, 0 < CCD </= 80, 80 < CCD </= 160 and 160 < CCD </= 300 mg/m(2) and their OS and nephrotoxicity compared. Pre-treatment plasma EBV DNA and clinical stage were incorporated into the RPA model to perform risk stratification. All patients were classified into either a high-risk group (n = 158, Stage IV), an intermediate-risk group (n = 193, EBV DNA > 2000 copy/mL & Stage I, II, III) or a low-risk group (n = 414, EBV DNA </= 2000 copy/mL & Stage I, II, III). The 5 year OS of CCRT vs. IMRT alone in the high-, intermediate- and low-risk groups after balancing covariate bias were 60.1 vs 46.6% (p = 0.02), 77.8 vs 64.6% (p = 0.03) and 86.2 vs 85.0% (p = 0.81), respectively. The 5 year OS of patients receiving CCD = 0, 0 < CCD </= 80, 80 < CCD </= 160 and 160 < CCD </= 300 mg/m(2) after balancing covariate bias in the high-risk group were 45.2, 48.9, 73.4 and 58.3% (p = 0.029), in the intermediate-risk group they were 64.6, 65.2, 76.8 and 83.6% (p = 0.038), and in the low-risk group they were 85.0, 68.1, 84.8 and 94.0% (p = 0.029), respectively. In the low-risk group, the 5 year OS of Stage III patients receiving CCD = 0, 0 < CCD </= 80, 80 < CCD </= 160 and 160 < CCD </= 300 mg/m(2) were 83.5, 76.9, 85.5 and 95.5% (p = 0.044), respectively. No Grade 3-4 nephrotoxicity occurred. Therefore, in our study, Stage I, II, & EBV DNA > 2000copy/ml and Stage III, IV elderly NPC patients may be CCRT beneficiaries. 80 < CCD </= 300 mg/m(2) is recommended for the high-risk (Stage IV) group, and 160 < CCD </= 300 mg/m(2) for the intermediate-risk (Stage I, II, III & EBV DNA > 2000copy/ml) and low-risk (Stage III & EBV DNA </= 2000 copy/ml) groups. No grade 3-4 nephrotoxicity occurred in any of the CCD groups.