Nomograms incorporating primary tumor response at mid-radiotherapy to predict survival in locoregionally advanced nasopharyngeal carcinoma

BackgroundA nomogram that incorporates tumor response at mid-radiotherapy (mid-RT) to predict the prognosis of locoregionally advanced nasopharyngeal carcinoma (LA-NPC) has not been established. MethodsThis study retrospectively reviewed 583 patients with LA-NPC who underwent magnetic resonance imaging scans at mid-RT (the fourth week of RT) between 2015 and 2019. ResultsPrimary tumor (PT) response at mid-RT was found to predict disease-free survival (DFS) and overall survival (OS). Independent factors from multivariable analysis to predict DFS and OS were assembled into nomograms with (nomograms A(mid-RT) and Bmid-RT) or without (nomograms A(baseline) and B-baseline) PT response. Internal validation revealed good performance of these nomograms in discrimination: C-statistics = 0.761 for nomogram A(mid-RT) and 0.809 for nomogram Bmid-RT, which showed better discrimination performance than (C-statistics: 0.755) nomogram A(baseline) and (C-statistics: 0.798) nomogram B-baseline (Z-statistic = 2.476, p < 0.05; Z-statistic = 1.971, p < 0.05). ConclusionThe nomograms based on PT response at mid-RT showed favorable predictive accuracy for DFS and OS in patients with LA-NPC.