Cancer Featured PYNK Women's health

Which lifestyle changes can help reduce the risk of breast cancer recurring?

Woman stretching
Written by Dr. Ellen Warner

I have treated patients with breast cancer for more than 30 years as a medical oncologist. And I have found that most of the women in my practice are desperately looking for things they can do beyond standard treatment to increase their chance of cure. Unfortunately, many fall prey to false claims they read over the Internet or hear from well-meaning friends and relatives. They adhere to extremely strict diets — no meat, no dairy, no sugar — or turn to various “supplements” with unproven effectiveness and often even unproven safety.

So I thought it would be helpful to review the literature to determine what evidence-based lifestyle changes women could make that would at least improve their overall health and, ideally, reduce their risk of dying of recurrent breast cancer. For this review, I teamed up with Julia Hamer, a pre-med student and former Sunnybrook summer research student with a degree in nutrition who is also an Olympic level athlete with her sights set on the 2020 Games in Tokyo.  Our review, which looked at 67 published papers, was published today in the CMAJ. (Listen to a podcast about the review.)

Exercise is most beneficial

Our review found that the single most important thing women with breast cancer can do (aside from follow their oncologists’ treatment recommendations) is start or continue exercising right from the moment of diagnosis, through active treatment (chemotherapy, radiation, surgery) and beyond.

We found that even a small amount is beneficial. A total of 30 minutes per day 5 days per week of moderate exercise is all that is necessary to achieve the benefits of about a 40% greater chance of survival (and reduced side effects of treatment including less nausea, fatigue, anxiety and depression). More hours per day (but not more vigorous exercise) may be even more beneficial. A mix of aerobic exercise and muscle strength training is ideal.

Other key takeaways from our review:

  • Avoid weight gain – For many reasons, most breast cancer patients gain weight after their diagnosis, which they find very difficult to lose. A weight gain of more than 10% of one’s initial body weight has been shown to increase the risk of breast cancer recurrence and death. More modest weight gain may not affect survival but often negatively affects body image and mood. While exercise is always helpful in avoiding weight gain, many women find that they have to consciously cut back on the amount and types of food they eat to avoid gaining weight, particularly if they’re on chemotherapy or hormone therapy.
  • Diet –no specific type of diet has been shown to reduce the risk of breast cancer recurrence. Evidence indicates that patients do not need to avoid soy and it may help with weight management if used to replace higher-calorie meat protein. Women should aim for a diet high in fruits, vegetables, lean protein and fibre, and low in saturated fats, simple sugars and alcohol. Such a diet should also help with weight management.
  • Vitamin supplementation – moderate consumption of vitamin C may be helpful although more evidence is needed. Vitamin D supplements may be taken to maintain adequate levels for bone strength, since chemotherapy and hormonal treatments can reduce bone density.
  • Smoking – stop smoking. While it is unclear if stopping smoking after a breast cancer diagnosis affects recurrence, the risk of death from smoking-related health issues is a strong reason to quit.
  • Alcohol intake – limiting consumption to one or fewer alcoholic drinks per day may help reduce the risk of a second breast cancer.

Lifestyle changes aren’t a substitute for other treatments

What I really want to emphasize, though, is that the breast cancer patients in the studies showing the benefits of lifestyle changes were also receiving conventional anticancer therapy; lifestyle changes should never be used as a substitute for standard therapy.

And most importantly, I want this to be clear: no woman should ever be made to feel guilty that her breast cancer has come back and spread because she didn’t make enough positive lifestyle changes. Some breast cancers have aggressive biology and will recur despite the most meticulous lifestyle behaviours.

This review and its key findings aim to help point women in the direction of lifestyle changes that could have a positive impact on overall health and on reducing breast cancer recurrence.



About the author

Dr. Ellen Warner

Dr. Ellen Warner is a medical oncologist at Sunnybrook’s Odette Cancer Centre.