Construction Of Competing Risk Nomogram For Bilateral Breast Cancer:Based On SEER Database

BACKGROUND&OBJECTIVE:In recent years,the incidence of bilateral primary breast cancer has increased.However,there is limited information from population-based cancer registries regarding prognostic features of bilateral primary breast cancer(BPBC).We cannot precisely predict the survival of patients with bilateral breast cancer.The aim of the study is to find out prognostic factors in BPBC by competing risk analysis.Based on this,we looked for a concise model and constructed a competing risk nomogram that could be used for individualized risk assessment in BPBC.METHODS:Female patients diagnosed with BPBC between 2004 and 2014 were randomly divided into training(n=7740)and validation(n=2579)cohorts from the Surveillance,Epidemiology,and End Results Database(SEER).We proposed five various models:a).The characteristics of bilateral tumor;b).The worse characteristics regardless of side;c).The characteristics of worse tumor;d).The characteristics of first tumor;e).The characteristics of second tumor.Multivariate Cox hazard regression and competing risk analysis were to explore prognosis factors in training cohort.Competing risk nomograms were constructed to combine significant prognostic factors to predict the 3-year and the 5-year survival of patients with BPBC.At last,in the validation cohort,the new score performance was evaluated with respect to the area under curve(AUC),concordance index(C-index),net reclassification index(NRI)and calibration curve.we drew receiver operating characteristic curves(ROC)of five models,and made a comparison among them.In addition,we conducted a descriptive analysis of the baseline clinical features of the included patients and used the Chi-square test to compare the characteristics of synchronous bilateral breast cancer(SBBC)and metachronous bilateral breast cancer(MBBC).RESULTS:We found out that age,interval time,lymph nodes invasion,tumor size,tumor grade and estrogen receptor(ER)status were:independent prognostic factors in both multivariate Cox hazard regression analysis and competing risk analysis.C-index in the model of the worse characteristics was 0.816(95%CI:0.791-0.840),of the bilateral tumors was 0.819(95%CI:0.793-0.844),of the worse tumor was 0.807(95%CI:0.782-0.832),of the first tumor was 0.744(95%CI:0.728-0.763)and of the second tumor was 0.778(95%CI:0.762-0.794).ROC reflected that model of the characteristics of bilateral tumor and model of the worse characteristics regardless of side performed best and there was no statistical significance between them.NRI of the 3-year and the 5-year between them was 2.7%and-1.0%.The calibration curves showed high concordance between the nomogram prediction and actual observation.CONCLUSION:The prognosis of BPBC depended on bilateral tumors.The competing risk nomogram of the model of the worse characteristics may help clinicians predict survival simply and effectively.Metachronous bilateral breast cancer(MBBC)presented poorer survival than synchronous bilateral breast cancer(SBBC).