Indexed on: 02 May '21Published on: 02 May '21Published in: International Journal of Radiation Oncology • Biology • Physics
To present a nomogram for prediction of overall survival (OS) in locally advanced cervical cancer patients (LACC) undergoing definitive radio-chemotherapy including image guided adaptive brachytherapy (IGABT). 720 patients with LACC treated with radio-chemotherapy including IGABT in 12 institutions (median follow-up 56 months) were analysed; 248 deaths occurred. Based on literature and expert knowledge, 13 candidate predictors for OS were a priori chosen. Missing data (7.2%) were imputed by multiple imputation and predictive mean matching. Univariate analysis (UA), multivariable Cox regression model (m-Cox) for OS stratified by centre were performed. Stepwise selection of predictive factors with the Akaike Information Criterion (AIC) was used to obtain a predictive model and construct a nomogram for OS predictions 60 months from diagnosis. This was internally validated by concordance probability as a measure of discrimination and a calibration plot. Thirteen potential predictive factors were evaluated; 10 reached statistical significance in UA (age, Hemoglobin, FIGO Stage, tumor width, corpus involvement, lymph node involvement, concurrent chemotherapy, dose to 90% of the high risk clinical target volume (CTVD90) Volume of CTV at the first brachytherapy (CTVVolumeBT), overall treatment time (OTT)). Four factors were confirmed significant within m-Cox (FIGO Stage, lymph node involvement, concurrent chemotherapy, CTVVolumeBT. The predictive model and corresponding nomogram were based on seven AIC-selected factors (age, corpus involvement, FIGO Stage, lymph node involvement, concurrent chemotherapy, CTVVolumeBT, OTT and showed promising calibration and discrimination (cross-validated concordance probability c=0.73). . This is the first nomogram to predict OS in LACC patients treated with IGABT. In addition to previously reported factors (age, FIGO stage, corpus involvement, chemotherapy delivery, OTT, lymph node involvement) status of primary tumor at the time of BT seems to be an essential outcome predictor. These results may facilitate individualized tailoring of treatment and patient counselling during the treatment. Copyright © 2021. Published by Elsevier Inc.