Development of a web-based prognostic model to quantify the survival benefit of cumulative cisplatin dose during concurrent chemoradiotherapy in childhood nasopharyngeal carcinoma.

PURPOSE: To quantify and predict the survival benefits of cumulative cisplatin dose during concurrent chemoradiotherapy (CC-CCD) in children and adolescents with locoregionally advanced nasopharyngeal carcinoma (CA-LANPC). MATERIALS AND METHODS: Patients with CA-LANPC who received first-line neoadjuvant chemotherapy (NAC) followed by concurrent chemoradiotherapy (CCRT) between September 2007 and April 2018 were evaluated. Recursive partitioning analyses (RPAs) helped identify the ideal thresholds of CC-CCD on disease-free survival (DFS). We then developed a web-based predictive model to quantify the survival benefit of CC-CCD for CA-LANPC. RESULTS: In total, 139 patients were eligible for the analysis. The median CC-CCD was 162 mg/m(2) (IQR, 138-192 mg/m(2)). The optimum cut-off point of CC-CCD was 160 mg/m(2) for DFS. Hence, we selected 160 mg/m(2) as the cut-off to classify CA-LANPC into either high or low CC-CCD groups for survival analysis. The 5-year DFS rates were 91.6% in the high (>/=160 mg/m(2)) CC-CCD group and 77.8% in the low (<160 mg/m(2)) CC-CCD group (P = 0.011). Multivariate analysis indicated CC-CCD (HR, 0.34; 95%CI, 0.13-0.87; P = 0.024), T stage (HR, 3.72; 95%CI, 1.35-10.22; P = 0.011), and EBV DNA (HR, 3.00; 95%CI, 1.00-8.97; P = 0.049) were independent prognostic factors and were incorporated into the prognostic model. N stage was also included due to its clinical importance. The predictive model was demonstrably accurate (C-index, 0.741) when predicting 5-year DFS rates. CONCLUSIONS: We built a predictive model to quantify the survival benefit of CC-CCD for CA-LANPC treated with NAC plus CCRT. This tool may improve individual treatment consultations and facilitate evidence-based decision-making.