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The Boston Globe

Health & wellness

Cancer survivors could benefit from better diet, exercise, weight loss

The American Cancer Society, for the first time Thursday, issued formal lifestyle recommendations aimed at those diagnosed with cancer, saying there was finally enough evidence from research studies to determine finite steps patients can take to lower their risk of recurrence.

“The science has gotten stronger,” said Dr. Otis Brawley, chief medical officer of the American Cancer Society. “Evidence suggests huge correlations between cancer and a triad combination of obesity, high caloric intake, and a lack of physical activity.”

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Some specific cancers -- such as breast, prostate, and colorectal cancer -- appear to be driven by lifestyle factors both in terms of whether they arise in the first place and whether they recur years later.

But that doesn’t mean patients who develop cancer or have a recurrence should blame themselves.

“This is about risk reduction,” emphasized Brawley. “It’s possible to do everything right and still have cancer return. I was talking to a young lady last week who told me that despite having regular mammograms, she was diagnosed with a stage 4 breast cancer. She wanted to know what she had done wrong, and I told her nothing.”

And, yes, plenty of folks diagnosed with lung cancer never smoked a day in their lives.

With all this in mind, cancer patients may want to take action to lower their risk of having a recurrence and improve their quality of life, especially since the recommendations made by the cancer society can also help lower their likelihood of other chronic illnesses like heart disease and diabetes. Here’s a list:

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1. Exercise. At least 20 observational studies indicate that physically active cancer survivors have a lower risk of cancer recurrences and improved survival compared with those who are sedentary, but studies only looked at certain cancers: breast, colorectal, prostate, and ovarian. One recent review study of breast cancer patients found that exercise was associated with a 34 percent lower risk of breast cancer deaths and a 24 percent lower risk of breast cancer recurrence. Clinical trials have demonstrated that exercise also improves a cancer survivor’s quality of life reducing the risk of depression, psychological distress, and fatigue.

Recommendation: Engage in at least 150 minutes a week of moderate intensity activity or 75 minutes a week of intense activity combined with strength training for all major muscle groups at least two days a week.

2. Diet. There’s no one ideal diet for cancer patients, and studies examining individual factors, like dietary fat intake, have had conflicting results, according to the guidelines. Likewise, a high sugar intake hasn’t been shown to increase the progression of cancer, though it can lead to obesity, which increases the risk of cancer recurrence so it’s smart to reduce added sugars in the diet. A diet high in processed red meat -- hot dogs, deli meats, sausage -- has been implicated in a higher risk of a number of cancers. And a high intake of fruits and vegetables has been found to be protective.

Recommendation: Eat at least two to three cups of vegetables and 1.5 to 2 cups of fruit every day. The best choices are dark green leafy, yellow, or orange-colored vegetables. For prostate cancer, tomato sauce appears to lower risk of recurrence. Choose fish, poultry, and low-fat dairy for protein or non-animal sources like soy protein, beans, and nuts. Limit red meat to two to four servings a week. (Here’s a more complete list of foods that protect against cancer.)

3. Body weight. Obesity has been associated with a greater risk of developing a host of cancers including breast, prostate, and colorectal. “And there are several studies that show breast cancer patients who gain weight after diagnosis and treatment are more likely to relapse or develop a different cancer,” said Brawley. Unfortunately, there’s only limited evidence to support the theory that losing weight will reduce the risk of recurrence. One study of breast cancer survivors indicated that a 6-pound weight loss was protective, but that finding needs to be confirmed.

Recommendation: Cancer survivors should strive to achieve and maintain a healthy weight with a body mass index between 18.5 and 25 (111 pounds to 150 pounds for a 5’5” person).

4. Dietary supplements. Although doctors have traditionally told cancer survivors to take vitamin and mineral supplements as an “insurance policy” for getting adequate levels of nutrients, the guidelines state that the practice has “come under scrutiny as more recent data suggest that multivitamin supplements may actually increase the risk of mortality.”

Recommendation: Nutrients should be ingested through whole foods if possible. Supplements should only be considered if a physician ascertains that there’s a nutrient deficiency in, say, vitamin D or vitamin B12 levels or if a registered dietician determines that nutrient intakes are falling persistently below the recommended levels.

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.

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