Abstract P6-19-01: Prognostic factors in male breast cancer: A population-based study

Abstract

Background: Male breast cancer (MaBC) is a relatively uncommon disease, representing less than 1% of all breast cancers. Given its rarity, information about prognostic factors is unclear and mainly extrapolated from data from female breast cancer. This represents an important challenge for the risk assessment and treatment decisions in men. The aim of this study was to analyze the characteristics of patients with MaBC and factors associated with prognosis over the past decade. Methods: We evaluated men with microscopically confirmed invasive breast cancer diagnosed between 2003 and 2012, reported to the Surveillance, Epidemiology and End Results (SEER) 18 registries program. Patients (pts) with other primary malignancy either before or after breast cancer were excluded. Pt characteristics were compared between tumor grades. Univariate and multivariate analyses were performed to determine the effects of each variable on overall survival (OS). Results: We included 2992 pts. Median age was 65 years (range 23-97). Median follow-up was 36 months (range 0-119). At diagnosis, ductal histology represented 85% of cases, ER positive 95.1% and PR positive 86%. Thirty-one percent were Stage I, 42% stage II, 18% stage III and 9% stage IV. Only 12.8% of pts had breast conservation and 23.7% received adjuvant radiotherapy. Tumor grade distribution was: 12.4% grade 1, 51.5% grade 2 and 36% grade 3/4. Pts with grade 3/4 tumors were more likely mixed ductal and lobular histology (p<0.0001), more often ER and PR negative (p<0.0001), presented with more advanced stage (p<0.0001), were more likely to have mastectomy and radiotherapy (p<0.0001 and p=0.001, respectively) and to die from breast cancer (p<0.0001). Univariate analysis showed that older age, black race, grade 3/4 tumors, stage IV disease, no surgery, no radiotherapy, ER negative tumors, PR negative tumors and unmarried pts had worse prognosis. Most deaths in the ER negative group occurred within the first 5 years (OS rate at 5 years 66.2%). OS rates between ER positive and ER negative groups were similar after 7.5 years (60.9% and 61.9%, respectively). In multivariate analysis, older age, grade 3/4 tumors, stage IV disease, no surgery, no radiotherapy, ER negative tumors and unmarried pts had shorter OS. Univariate pMultivariate pAge<0.0001<0.0001Race0.0001NSGrade<0.00010.006Stage<0.0001<0.0001Surgery<0.00010.0001Radiation0.020.004ER0.030.04PR0.005NSMarital status<0.0001<0.0001HistologyNS Conclusions: MaBC is most commonly diagnosed at early stages of disease. Tumors are frequently ductal in histology with high rates of ER positivity, however grade 1 is uncommon. We observed significant differences in pt characteristics according to tumor grade. The main difference in OS by ER status is seen during the first 5 years. Age at diagnosis, tumor grade, stage, surgery, radiotherapy, ER and marital status have clear influence on OS in MaBC over the past decade. Citation Format: Leone JP, Zwenger AO, Iturbe J, Leone J, Leone BA, Vallejo CT, Bhargava R. Prognostic factors in male breast cancer: A population-based study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-19-01.