Updated: Dec 6, 2018
A prospective study from found that women with TNBC who exercised more than 2.5 hours per week at >7.6 metabolic equivalents (METs) hours had lower risk of total and recurrence/disease-specific mortality than did non-exercisers. See Research Gate. Hazard ratio for recurrence was 0.58 (95% CI = 0.39, 0.86) with a decent confidence interval.
1 metabolic equivalent of energy (MET) is the energy it takes to burn 1 kcal/kg/hr. Walking and hiking at 4.5 mph is 7.0 METS. Jogging at 6 mph is 10.0 METS.
Also see the article in the Guardian online. PubMed Health has a nice summary of exercise and breast cancer recurrence. Additionally, there is a multi-ethnic cohort by George, et. al. of 670 women with early breast cancer. The study shows an 89% reduction in cancer-specific mortality and a 91% reduction in all cause mortality in patients who ate healthier diets and reported regular physical activity.
Looking back to the large study of 2,987 patients by Holmes reported in JAMA in 2005, 9-14.5 MET hrs per week (150-250 minutes of moderate-intensity exercise) was associated with a 50% reduction in breast cancer death compared with those patients who achieved less than 3 MET hrs per week.
Friedenreich, et al. reported in a systematic review of breast cancer patients that post-diagnosis exercise resulted in a 37% reduction in cancer-specific mortality.