Exercise May Lower Risk of Breast Cancer Coming Back in Some Women

Research shows that people who exercise regularly before and after being diagnosed with breast cancer have a lower risk of dying from the disease. But can being active before starting breast cancer treatment reduce the risk of the cancer coming back in another part of the body? A French study published in The Journal of Clinical Oncology suggests that for some women it can. 

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  Pre-menopausal women who did 90 minutes to five hours of moderate exercise per week (brisk walking, bike riding) before starting treatment for hormone receptor-negative breast cancer had a lower risk of metastatic recurrence than women who didn’t exercise.

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  This reduction in metastatic recurrence risk was only seen in pre-menopausal women; post-menopausal women didn’t seem to get the same benefits from exercise.

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  The lower metastatic recurrence risk was only seen for cancers that were hormone receptor-negative. The cancers could be HER2-positive or HER2-negative.

This study offers yet another reason to make exercise part of your daily routine. Not only can it reduce your risk of being diagnosed with breast cancer, boost your sex drive, and ease fatigue, it can lower the risk of metastatic recurrence if you’re diagnosed with hormone receptor-negative disease at a young age.

If you’re busy, finding time to exercise almost every day can be hard. Exercising also can be extremely difficult if you’re recovering from breast cancer treatment. Maybe you exercise in 20- or 30-minute sessions that add up to about five hours per week. Walking is a great way to start. Maybe you walk 30 minutes before going to work and 30 minutes on your lunch break. Or you can make plans to walk with a friend after work -- you’re more likely to stick with exercise if someone else is counting on you. Plus, you can socialize at the same time.

If you’re new to exercise, you may want to work with a qualified trainer who can help you start slowly and help you progress.

The study included more than 10,350 women (average age: 56 years) who were diagnosed with early-stage breast cancer between 2012 and 2018. About 40% of the women were pre-menopausal and 13% had been diagnosed with hormone receptor-negative breast cancer.

The women filled out a standard questionnaire that asked about the amount and intensity of physical activity they did before they were diagnosed. The researchers converted the women’s physical activity before diagnosis into a measure of energy expended during exercise called MET. They then followed up with them for years after they completed breast cancer treatment.

Over an average of five years, there were 502 cases of metastatic recurrence among the women.

MET stands for “metabolic equivalent of task.” It’s a measure of the energy used or calories burned during physical activity. One MET is the amount of energy you use while sitting quietly. Five MET hours per week is equal to about 90 minutes of moderate exercise per week, and 25 MET hours is equal to about five hours of moderate exercise per week.

Overall, women who exercised between five and 25 MET hours per week at the time of breast cancer diagnosis were less likely to have a metastatic recurrence than those who exercised less than five MET hours per week. 

The researchers then looked to see if the reduction in risk of metastatic recurrence varied by breast cancer subtype and menopausal status. They found that the benefits of exercise were limited to women diagnosed with hormone receptor-negative breast cancer. Similarly, the benefits of exercise on metastatic recurrence were only seen in pre-menopausal women.

Still, research shows that hormone receptor-positive breast cancer is more likely than hormone receptor-negative breast cancer to come back up to 20 years after diagnosis. Since the study follow-up time was only five years, it may have been too short to show a difference in recurrence rates for that type of breast cancer.

Davide Soldato et al. Dose/Exposure Relationship of Exercise and Distant Recurrence in Primary Breast Cancer. JCO 42, 3022-3032(2024).