Prognostic Implications Of The Pathological Prognostic Staging System Of The AJCC 8th Edition For Patients With HER2-positive Breast Cancer

Objective:The current study was designed to validate the prognostic value of the pathological prognostic（PP）stage and anatomic stage of the American Joint Committee on Cancer（AJCC）Cancer Staging System 8^th edition for HER2-positive breast cancer.Materials and Method:A total of 10,323 eligible patients with HER2-positive breast cancer diagnosed between 2010 and 2015 were selected from the SEER database.We classified all the patients according to the anatomic stage and the PP stage.Breast overall survival（OS）were compared between the two staging system.Statistical methods,includingKaplan-Meieranalyses,time-dependent receiver-operating-characteristic（ROC）analysis,the area under the curve（AUC）value,the Akaike information criterion（AIC）and the Bayesian information criterion（BIC）,were used to evaluate the prognostic values of the anatomic stage and PP stage.Results:In our study,we found that the stages of 704（6.82%）patients were changed,and all patients were down-staged regardless of the histological grade（GI 1.44%,GII22.94%,GIII 75.62%）.Kaplan-Meier survival curves were generated to demonstrate the significant differences in each PP stage（P<0.001）.Finally,the AUC values suggested that both staging systems had prognostic value for overall survival,and the AIC and BIC analyses showed that the PP stage was a better predictive model（anatomic stage versus PP stage:AIC,4354.226 versus 4247.858;BIC,4448.374 versus 4327.521,respectively）.Conclusions:Our study indicated that the pathological prognostic stage of the AJCC8th edition had better prognostic value than the traditional anatomic stage in a HER2-positive breast cancer cohort,thereby deserving further study for validation.