Breast Cancer Mortality Higher in Men than Women

The findings of a study published in JAMA Oncology show that mortality after breast cancer diagnosis is higher among male patients compared with to female patients.

In a large, nationwide, registry-based cohort study, researchers assessed 16,025 male patients (average age, 63) and 1,800,708 female patients (average age, 60) who were diagnosed with breast cancer between January 2004, and December 2014 using the National Cancer Database to obtain all data. The key outcome in this study was defined as overall survival. The secondary outcome was specified as 3-year and 5-year mortality. The researchers evaluated mortality differences using Kaplan-Meier analysis. They also appraised the roles of race/ethnicity, clinical characteristics, treatments, and access-to-care factors between sex and mortality using nested Cox proportional hazards regression models. Data analysis was conducted between September 2018 and January 15, 2019.

According to the results of the study, juxtaposed to female patients, male patients had higher mortality across all stages. The results showed that among men, the overall survival rate was 45.8% (95% CI, 49.5 to 54.0; P < .001), the 3-year rate was 86.4% (95% CI, 85.9 to 87.0; P < .001), and the 5-year rate was 77.6% (95% CI, 76.8 to 78.3; P < .001). For women, the overall survival rate was 60.4% (95% CI, 58.7 to 62.0; P < .001), the 3-year rate was 91.7% (95% CI, 91.7 to 91.8; P < .001), and the 5-year rate was 86.4% (95% CI, 86.4-86.5; P < .001). Overall, the study observed that clinical characteristics and undertreatments were associated with a 63.3% increased mortality rate for male patients.

Moreover, the study found a higher proportion of deaths in men were explained by these factors in the first 3 years after breast cancer diagnosis (66.0%) and in all patients with early-stage cancer (30.5% for stage I and 13.6% for stage II). However, sex remained a notable factor linked with overall mortality (adjusted hazard ratio [HR], 1.19; 95% CI, 1.16 to 1.23) as well as mortality at 3-year (adjusted HR, 1.15; 95% CI, 1.10 to 1.21) and 5-year (adjusted HR, 1.19; 95% CI, 1.14 to 1.23) analyses, even after adjustment for clinical characteristics, treatment factors, age, race/ethnicity, and access to care.

The authors wrote in their conclusion that “such disparity appeared to persist after accounting for clinical characteristics, treatment factors, and access to care, suggesting that other factors (particularly additional biological attributes, treatment compliance, and lifestyle factors) should be identified to help in eliminating this disparity.”