Lifestyle Modifications May Improve Health and Prognosis in Breast Cancer Patients Interview with:
Ellen Warner, MD, FRCPC, FACP, M.Sc.
Affiliate scientist
Sunnybrook Health Sciences Centre
Toronto, ON What is the background for this review?

Response: As a medical oncologist who has treated breast cancer patients for over 30 years, I have found that most of the women in my practice are desperately looking for things they can do beyond standard surgery, radiation, chemotherapy, etc. 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.  As a result they turn to absurdly restrictive diets (eg. No meat, dairy or sugar) or to ‘supplements’ with unproven effectiveness or even safety. So I thought it would be helpful to review the literature to determine what evidence-based lifestyle changes these 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 thought it would be great to team up with Julia Hamer, a pre-med student with a degree in nutrition who just happens to also be an Olympic level athlete! What is the background for this review?

Response: The single most important thing that breast cancer patients can do, aside from follow their oncologists’ treatment recommendations, is start/continue exercising right from the moment of diagnosis, through active treatment and beyond. 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.

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.

As for the ideal diet, our review found that eating soy is perfectly safe and possibly even helpful, but no specific diet has been proven to reduce the risk of breast cancer recurrence. Alcohol doesn’t seem to increase the risk of recurrence but it’s high in calories and may increase the risk of a second breast cancer.  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.

There is no proof than any specific vitamins or supplements reduce the risk of cancer recurrence. What recommendations do you have for future research as a result of this study?

Response: Most of the research is what we call ‘retrospective’.  We look back and compare the outcome of women who have or have not made a specific lifestyle intervention.  The problem with these studies is that women who choose to change their lifestyle (eg. exercise more) may differ from other women in a number of other ways.  They may also be more likely to eat a healthy diet and take their medications regularly. What we need are more ‘prospective randomized studies’ in which two otherwise identical groups of women are randomly assigned to a specific lifestyle intervention (such as a specific diet or dietary supplement) and then followed for many years.  Such studies are very difficult and expensive to run but most likely to give definitive results. Is there anything else you would like to add?

Response: While many women are initially highly motivated to make positive lifestyle changes after a breast cancer diagnosis, they often  ‘fall off the wagon’ when active treatment is over.  The challenge is to make these permanent lifelong changes.

It’s important to emphasize 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.

Perhaps most importantly, no woman should ever feel guilty for causing her breast cancer to 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. Thank you for your contribution to the community.


Julia Hamer HBSc, Ellen Warner MD MSc. Lifestyle modifications for patients with breast cancer to improve prognosis and optimize overall health. CMAJ, February 2017 DOI: 10.1503/cmaj.160464

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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Last Updated on February 23, 2017 by Marie Benz MD FAAD