Male breast cancer survival in Mexico between 2007 and 2016: A retrospective cohort.

1116 Background: Male breast cancer represents around 1% of all breast cancers worldwide. Due to its rarity, it is more likely to be diagnosed at advanced stages than in women, and survival rates tend to be lower than in female patients. Information about survival in male breast cancer in low- and middle-income countries (LMIC) is scarce. Methods: We conducted a retrospective cohort study cross-linking nationwide reimbursement claims for breast cancer cases between 2007 and 2016 treated within the Seguro Popular health financing scheme to a national mortality registry in Mexico. Age, municipality of residence, clinical stage, and year of treatment initiation were described. Facilities were classified according to location, total breast cancer patient volume, and type of funding. We estimated 5-year overall survival (OS) with 95% confidence intervals (95% CI) through the Kaplan Meier method and used the log-rank test to compare differences between patient groups. Patients with in situ disease and missing data for clinical stage were excluded from survival analyses. Results: We identified 268,703 claims representing 60,846 patients, from which 328 were male (0.53%). Median age was 56 years (IQR 48-67). At treatment initiation, 20.7% of patients had early disease, 46.3% had locally advanced (LA) disease and 15.5% metastatic disease; clinical stage information was missing in 16% of patients Most patients (86.6%) were treated at public facilities, and 40.5% were treated at high volume facilities. With a median follow-up of 4.1 years, five-year OS in the whole cohort was 64.3% (CI 95% 58.1-71.2). In patients with early-stage disease, 5-year OS was 78.7% (95% CI 67.0-92.4), in LA disease 66.3% (95% CI 58.4-75.3) and in metastatic disease 39.7% (95% CI 27.5-57.5) (p <0.001). Patients with LA disease treated at a private facility had improved 5-year OS (88.9%) compared to those who were treated at a public facility (62.8%) (p=0.033). We did not find any other significant differences in survival according to patient or facility characteristics, including patient volume. Conclusions: These results represent the largest cohort to describe survival in men with breast cancer in Latin America. We found a larger proportion of men diagnosed with metastatic disease than described in women in Mexico, and lower than expected survival in patients with early-stage and LA disease.