The effect of exercise and educational programs for breast cancer patients on the development of breast cancer-related lymphoedema: secondary endpoint from a randomized controlled trial in the Setouchi Breast Project-10.

Background: Although the association between higher physical activity and preventive effect on breast-cancer-related lymphoedema (BCRL) has been reported, it is unclear what intervention is optimal. We aimed to investigate the effect of exercise and educational programs on BCRL development.

Methods: This study was a secondary endpoint analysis from a prospective randomized controlled trial. We enrolled patients with stage 0-III breast cancer from March 2016 to March 2020 and randomly assigned them to the control (n = 111), education (n = 115), or exercise (n = 104) group. As secondary endpoint, we assessed the incidence of and preventive effect on BCRL at 12 months post-intervention.

Results: There were no significant differences in the incidence of BCRL at 12 months post-intervention between the exercise and control groups (9.8% and 10.8%, P = 0.83) and the education and control groups (11.6% and 10.8%, P = 1.00). There were no significant differences in time to BCRL onset from the day of surgery between the exercise and control groups (event rate at 12 months: 20.7% and 17.2%, log-rank, P = 0.54) and the education and control groups (18.8% and 17.2%, log-rank, P = 0.57). The multivariable analyses indicated that axillary dissection and obesity significantly increased the risk of BCRL [hazard ratio (HR): 2.36, 95% confidence interval (CI) 1.52-3.67 and HR: 1.68, 95% CI 1.07-2.63, respectively].

Conclusions: The intervention did not decrease the risk of BCRL, and axillary dissection and obesity were the risk factors of BCRL.

Trial registration number: UMIN000020595 at UMIN Clinical Trial Registry.