Obesity and Smoking are Bad for Breast Cancer Patients

Kananaskis Country. (Dr. Noorali Bharwani)
Kananaskis Country. (Dr. Noorali Bharwani)

“Although more than 90 per cent of patients with breast cancer have early stage disease at diagnosis, about 25 per cent will eventually die of distant metastasis,” says an article in the Canadian Medical Association Journal (CMAJ February 21, 2017) written by Julia Hamer and Ellen Warner.

In their review article Hamer and Warner say if breast cancer patients make positive lifestyle changes then they can reduce the risk of breast cancer recurrence and death. It can also be psychologically beneficial by empowering them, since the feeling of loss of control is one of the challenges of a cancer diagnosis.

The authors of the article reviewed the role of lifestyle factors, particularly weight management, exercise, diet, smoking, alcohol intake and vitamin supplementation, on the prognosis of patients with breast cancer.

Body weight influences the prognosis for breast cancer patients.

Women who gain weight during or after treatment of breast cancer have been consistently shown to be at higher risk of breast cancer–related death. Also, women who are overweight or obese at the time of diagnosis have a poorer prognosis.

Most women with breast cancer gain weight both during and after active treatment, and much of the weight is never lost. This increases the risk of recurrence and reduces survival.

There are many reasons for weight gain including stress eating, reduced activity because of fatigue or other treatment-related adverse effects, lowered metabolic rate from chemotherapy, and use of pre- and post-chemotherapy medications such as dexamethasone.

What role can exercise play in improving prognosis?

A recent review of the effect of lifestyle factors on breast cancer mortality concluded that physical activity has the most robust effect of all lifestyle factors on reducing breast cancer recurrence.

Patients should be encouraged to engage in at least 30 minutes of moderate-intensity physical activity at least five days of the week, or 75 minutes of more vigorous exercise, along with two to three weekly strength training sessions, including exercises for major muscle groups.

Both the Canadian Cancer Society and the American Cancer Society have endorsed this recommendation, says the CMAJ article.

Can a change in diet improve outcomes?

There is currently no particular style of diet that has been found to be more beneficial than another for reducing the risk of breast cancer recurrence.

Studies from the United States and China found that high consumption of soy protein or soy isoflavones after breast cancer diagnosis was associated with a 26 per cent decrease in cancer recurrence.

Is there a benefit from quitting smoking and reducing alcohol consumption?

Yes. Recent observational studies have shown women with breast cancer who have a substantial smoking history have increased breast cancer deaths compared with those who never smoked, says the article. Findings are too inconsistent to conclude alcohol consumption affects breast cancer outcomes.

There is no evidence vitamins help improve cancer prognosis.

“Of all lifestyle factors, physical activity has the most robust effect on breast cancer outcomes,” says the article.

Follow the recommended 150 minutes of moderate to vigorous exercise or 75 minutes of vigorous exercise per week, along with two to three weekly sessions of strength training.

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