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Routine exercise, maintaining a healthy weight may help cancer outcomes

Note: This post is written by the team of The ONE Group (Oncology – Nutrition – Exercise) at Penn State College of Medicine as part of a first-person blog about their work. Learn more about the group here.

This month we’ll be talking about the benefits that lifestyle interventions, specifically, exercise and weight loss, can have when it comes to breast cancer.

It is well understood that engaging in regular exercise and maintaining a healthy body habitus has many health benefits. What many people might not realize is over the past couple of decades there has been extensive research demonstrating the benefits of lifestyle interventions with respect to cancer, specifically, breast cancer. Regular exercise and weight loss can modify someone’s risk profile potentially altering their chances of developing breast cancer, having complications from breast cancer or breast cancer treatment, dying of breast cancer, having a cancer recurrence, and improving overall quality of life. Below are some statistics related to body habitus and breast cancer outcomes:

  • For every five unit increase in body mass index (BMI) there is a 12% increased risk of cancer recurrence in breast cancer survivors.
  • For every five pounds gained after breast cancer diagnosis there is a 12% increase in dying from breast cancer.
  • For every five pounds gained after breast cancer diagnosis there is a 13% increase in dying from any cause.

Unfortunately, it is not well understood why women who engage in regular exercise and maintain a healthy body habitus receive these benefits. Currently, there is an increasing amount of research being done to better understand what about exercise and body habitus, on a molecular level, results in the benefits mentioned previously. The end goal is to be able to prescribe specific lifestyle interventions that maximize these benefits and help patients achieve the best possible outcome.

One of the theories for why exercise and maintenance of a healthy body habitus improves breast cancer outcomes is related the body’s production of insulin and how tissues in the body respond to insulin. Yes, that’s right, the same insulin that is involved in diabetes. It is thought that insulin might play a role in the development, growth, and recurrence of breast cancer. A study from the Penn State Cancer Institute and College of Medicine published in 2021 looked at the individual and combined effect of exercise and weight loss interventions in breast cancer survivors with overweight or obesity.  The goal of the paper was to determine what lifestyle intervention was most effective at targeting changing body habitus and altering insulin levels. The interventions were a control group, exercise alone (aerobic and strength training), weight loss alone (caloric restriction/diet), and combined exercise and weight loss. The study showed the best way to alter body composition was through weight loss via caloric restriction, either alone or in combination with exercise. It also demonstrated that the best way to alter insulin levels was through weight loss via caloric restriction either alone or combined with exercise.

Although this study suggests that weight loss via caloric restriction with or without exercise is best for altering body composition, it does not mean that engaging in aerobic and resistance exercise has no value. There are many proven benefits to engaging in regular exercise outside of the effect it has on cancer risk modification. Remember, it is unclear what the exact benefit of exercise is, which means it should still be considered a valuable activity. What this study suggests is that if we want to prescribe lifestyle interventions that maximize some of the cancer-related benefits, then the most effective way is to utilize a combination of exercise and diet to help create the best possible outcomes for

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