Development And Validation Of A Nomogram For Predicting Radiation-induced Temporal Lobe Injury In Nasopharyngeal Carcinoma

Research background and purpose:Radiation-induced temporal lobe injury(TLI)is one of the most serious late complications after definitive radiotherapy of nasopharyngeal carcinoma patients.We aimed to develop and validate a nomogram for prediction on radiation-induced temporal lobe injury in patients with nasopharyngeal carcinoma.Materials and Methods:The prediction model was developed based on a cohort that consisted of 194 patients with clinicopathologically confirmed nasopharyngeal carcinoma,and the data was gathered from January 2008 to December 2010.TLI was diagnosed by follow-up enhanced magnetic resonance imaging.Clinical factors associated with TLI and Dose-volume histograms for 388 evaluable temporal lobes were analyzed.Multivariable Logistic regression analysis was used to develop the predicting model,which was conducted by R software.The performance of the nomogram was assessed with respect to its calibration and discrimination.Internal validation was assessed.An external validation cohort contained 197 patients from January 2011 to December 2013.Results:Among the 391 patients,77 patients developed TLI.40 patients had bilateral TLI and 37 patients had unilateral TLI.The median time of radiation temporal lobe injury was 36.5 months.Univariate analysis of temporal lobe Dmax(P <0.001),D1cc(P<0.001),T stage(P <0.001),diabetes(P = 0.035),and NRL(P = 0.003)were related with TLI in primary group.Multivariate Logistic regression showed that Dmax,D1 cc,T stage,and NLR were independent prognostic factors of radiation temporal lobe injury.Predictors contained in the prediction nomogram included Dmax(the maximum point dose)of temporal lobe,D1cc(the maximum dose delivered to a volume of 1 mL),T stage,and neutrophil-to-lymphocyte ratios(NLR).The Internal validation showed good discrimination,with a C-index of 0.847 [95%CI 0.800 to 0.893],and good calibration.Application of the nomogram in the external validation cohort still obtained good discrimination(C-index,0.811 [95% CI,0.751 to 0.870])and acceptable calibration.Conclusions:This study presents a nomogram that incorporates Dmax,D1 cc,T stage,and NLR,which may be conveniently used to facilitate the individualized prediction of TLI in patients with nasopharyngeal carcinoma.