WASHINGTON, DC — Because male breast cancer is a rare although increasingly recognized disease, there are limited data on modifiable risk factors. Not as much as known about the condition in men vs. women, where it is significantly more common.
One unanswered question has been whether the inverse association between cardiorespiratory fitness (CRF) and breast cancer risk reported in women is similar to the association between CRF and breast cancer in men. A recent study published in the Journal of Sport and Health Science sought to evaluate the association between CRF and the incidence of male breast cancer in a large, nationally representative cohort of U.S. veterans.1
Researchers from the DC VAMC and George Washington University led the effort, analyzing data from 777,618 male veterans who completed an exercise treadmill testing (ETT) between 1999 and 2024 within the VHA and had no evidence of breast cancer prior to the ETT. CRF was expressed in peak metabolic equivalents (METs) in participants who were categorized into 4 age-adjusted CRF categories based on the peak METs achieved. Researchers from the VA Palo Alto, CA, Health System and Stanford University, as well as Rutgers University in New Brunswick, NJ, also participated in the study.
Defined as the primary outcome was incident male breast cancer, ascertained through the VA Computerized Patient Record System. Results were adjusted for age, race, body mass index, hypertension, diabetes (T2DM), chronic kidney disease, smoking and alcohol use.
Over a median follow-up of 10.7 years 518 men were diagnosed with breast cancer. After multivariable adjustment, age (HR = 1.24, 95% confidence interval (95%CI): 1.14-1.36) per decade, chronic kidney disease (HR = 2.13; 95%CI: 1.41-3.23), hypertension (HR = 1.57; 95%CI: 1.28-1.92), T2DM (HR = 1.24; 95%CI: 1.02-1.51), and poor CRF (HR = 1.69; 95%CI: 1.24-2.30) were found to be the strongest predictors of breast cancer. In fact, compared to patients in the lowest CRF category, breast cancer risk was 41% lower for individuals in the highest CRF quartile (HR = 0.59; 95%CI: 0.44-0.81).
“Higher CRF was independently associated with a substantially lower risk of breast cancer in men,” the authors concluded. “These findings suggest that CRF may represent a modifiable risk factor in the prevention of male breast cancer, underscoring the broader importance of physical fitness in reducing cancer risk across sexes.”
- Faselis C, Kokkinos P, Samuel IBH, Murphy R, Pittaras A, Ladas A, Korompeli L, Collier S, Myers J. Cardiorespiratory fitness and male breast cancer association: The ETHOS cohort. J Sport Health Sci. 2026 Aug 14:101167. doi: 10.1016/j.jshs.2026.101167. Epub ahead of print. PMID: 42600934.