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Exercise is most important lifestyle factor in reducing risk of breast cancer recurrence, study finds

A new study of lifestyle factors in breast cancer survivors found that exercise had the most powerful effect in reducing the risk of breast cancer recurrence and death. Maintaining a healthy weight was also linked to lower risk of recurrence.

Researchers Julia Hamer and Ellen Warner from Sunnybrook Health Sciences Centre in Toronto reviewed results from 67 research studies published in the past 10 years that looked at breast cancer survival and lifestyle factors. Their review includes results for exercise, weight management, diet, smoking, vitamin supplements and alcohol consumption.

Key results include:

  • Exercise was the most important factor. The researchers found that exercising the recommended 150 minutes per week (or half an hour, five days per week) was linked to a 40 per cent reduction in breast cancer recurrence and death. However, they also noted that few breast cancer survivors meet those exercise goals.
  • Gaining weight during breast cancer treatment or afterwards was associated with an increased recurrence risk and lower survival rates.
  • Recurrence and survival rates were similar for “Western-style” diets that included processed foods and red meats, and more health-conscious diets that included more fruits, vegetables, whole grains and chicken.
  • Eating soy did not increase risk of recurrence. In fact, there is some evidence that eating soy may be linked to a reduction in recurrence risk.
  • Saturated fat intake – from high-fat dairy products in particular – may be linked to higher mortality risk from breast cancer.
  • Smoking is linked to higher breast cancer mortality. Smokers who quit following a breast cancer diagnosis have higher survival rates than those who keep smoking, but it’s not clear whether that includes higher breast-cancer specific survival.
  • There is some evidence that moderately increasing vitamin C intake may be linked to lower breast cancer mortality, but this result needs to be confirmed in clinical trials.
  • Low vitamin D levels at diagnosis have been linked to higher mortality in breast cancer patients, but researchers don’t know if taking supplements can counteract this.
  • Findings about alcohol consumption were inconsistent for recurrence and mortality, but limiting alcohol to one drink a day or less was linked to reduced risk of a second primary breast cancer.

The research was published in CMAJ Open on Feb. 21, 2017, and is available online. The review includes patient-friendly summaries of the results.

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  • A publication of:
  • Women's College Hospital