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Lifestyle changes that impact breast cancer risk

Dr. Ellen Warner
Written by Dr. Ellen Warner

As a medical oncologist, I have treated patients with breast cancer for more than 35 years. Most are looking for things they can do beyond standard treatment to increase their chance of cure. Unfortunately, many fall prey to false claims they read online 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 safety.

In 2017, undergraduate student Dr. Julia Hamer and I reviewed the literature to determine what evidence-based lifestyle changes women could make to improve their overall health and reduce their risk of dying of recurrent breast cancer. Our review of 67 published scholarly papers was published in the Canadian Medical Association Journal. Here is a summary of our findings then, what’s been learned since and some helpful resources that are available now.

Exercise

Aside from following their recommended treatment plan, exercise is the single most important thing women with breast cancer can do. That means starting or continuing exercise right from the moment of diagnosis, through active treatment (chemotherapy, radiation, surgery) and beyond. We found that even a small amount is beneficial; 30 minutes per day, five days per week of moderate exercise, may boost survival rates by about 40 per cent. More hours per day (but not more vigorous exercise) may be even more beneficial. It appears that a mix of aerobic exercise and muscle strength training is ideal. Importantly, exercise is also linked to a reduction in treatment side effects like nausea, fatigue, anxiety and depression.

A more recent study, looking at women at high-risk for recurrence, supported the benefits of exercise. It found women who met the above minimum exercise guidelines before their diagnosis, as well as two years after treatment, had a 55 per cent lower risk of recurrence and a 68 per cent reduced risk of death from any cause. Women who did not meet the guidelines prior to their diagnosis, but did at the two-year follow-up, had almost a 50 per cent lower risk of breast cancer recurrence and a 43 per cent lower risk of death from any cause.

Weight gain

Weight gain of more than 10 per cent of one’s initial body weight has been shown to increase the risk of breast cancer recurrence and death. Exercise, as well as guidance from a registered dietitian, can be helpful in maintaining a healthy weight.

Diet

No specific type of diet has been shown to reduce the risk of breast cancer recurrence. Evidence shows that patients do not need to avoid soy, and it may actually help with weight management if used to replace higher-calorie meat proteins. Women should aim for a diet high in fruits, vegetables, lean protein and fibre, and low in saturated fats, simple sugars and alcohol. A high-calcium diet is helpful for maintaining bone health, and is preferable to supplements.

Vitamin supplements

Moderate consumption of vitamin C may be helpful, but more evidence is needed. Because chemotherapy and hormonal treatment can reduce bone density, vitamin D supplements should be taken by all women to maintain adequate levels for bone strength. As vitamin D requires fat to be absorbed properly, be sure to take it with a meal if choosing the pill form.

Smoking

Simply put, stop smoking. While it’s unclear if quitting after a breast cancer diagnosis affects recurrence, the risk of death from smoking-related health issues is a strong reason to butt out.

Alcohol intake

Limiting alcohol intake doesn’t affect the risk of recurrence but will reduce the risk of developing a new breast cancer. Aim to hydrate with water. All women, especially those on chemotherapy, should try to drink two litres of water daily. Having water available during and after exercise is particularly important.

Final thoughts

As powerful as lifestyle changes can be, they are never a substitute for the standard treatments your health-care team has prescribed. The breast cancer patients who benefitted from lifestyle changes in the reviewed studies were also receiving conventional anticancer therapy.

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 behaviors.

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

Helpful resources:

Exercise
Smoking Cessation
Alcohol and Drugs

About the author

Dr. Ellen Warner

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