The predicting value of the 8th edition of American Joint Committee on Cancer staging manual in mucinous breast cancer

Abstract

Objective: The current study aimed to evaluate the predictive performances of anatomic staging system (AS) and prognostic staging system (PS) proposed in the 8th edition American Joint Committee on Cancer (AJCC) staging manual in patients with pure mucinous breast cancer (PMBC). Methods: Clinicopathologic features and follow-up information were collected from a total of 3628 patients with PMBC. Breast cancer-specific survival (BCSS) were compared among patients in different stage groups. Likelihood ratio (LR) χ(2), Akaike information criterion (AIC) and Harrell's concordance index (C-index) were used to evaluate the predictive performances of AS and PS in PMBC. Results: In PMBC, BCSS was associated with tumor size (P=0.002), lymph node status (P=0.002), grade(P=0.003), PR status(P=0.017)and the receipt of radiation. Compared to AS, 1326 patients (37.54%) underwent stage change after applying PS, with 6.50% upstaged and 37.04% downstaged. There were significant differences in BCSS among patients of different stages under the AS and PS (P<0.001). However, PS was not superior to AS in predicting prognosis (AS vs PS, LR χ(2): 16.41 vs 17.5; AIC: 357.44 vs 358.35; C-index, 0.72 vs 0.73, P=0.667). Conclusions: Both of AS and PS proposed in the 8th edition American Joint Committee on Cancer (AJCC) staging manual were predictive factors in patients with PMBC. Compared with AS, the PS did not show superiority in prognosis prediction among patients with PMBC.