Matched-pair long-term survival analysis of male and female patients with breast cancer: a population-based study

Background: Previous studies found that the long-term survival of male breast cancer patients differed from those of female patients, however, the conclusions were contradictory. We conducted the study to examine the sex disparity in breast cancer survival by carefully controlling demographic and clinical factors using data from the Shanghai Cancer Registry (SCR).

Methods: Every male breast cancer patient was matched with four female patients by the diagnosis year, age, stage, and histology. We used Kaplan-Meier survival estimates to calculate the cumulative observed overall survival (OS) and cancer-specific survival (CSS) rates and log-rank tests to compare the survival rates by sex. We used Cox proportional-hazards regression models to assess the association between sex and risk of death.

Results: A total of 50,958 patients with breast cancer (0.85% male) were registered in the SCR between 2002 and 2013. After matching, 434 male and 1,736 female patients were included in the study. With a median follow-up of 10 years, men with breast cancer showed worse OS (P<0.001) and CSS (P<0.001) than did women. The 5- and 10-year OS rates for male and female patients were 67.27% and 77.75%, and 45.95% and 62.60%, respectively; the 5- and 10-year CSS rates for male and female patients were 70.19% and 79.79%, and 50.57% and 67.20%, respectively. Compared with women, men had 65% increased risk of overall death [95% confidence interval (CI): 1.42-1.92] and 70% increased risk of cancer-specific death (95% CI: 1.44-2.00).

Conclusions: This study found male patients with breast cancer had poorer long-term survival than women in China.