Cancer Risk and Cancer Survivors

Even After Cancer, Habit Change is Hard

A recent study made headlines when it announced that among more than 114,000 adults, cancer survivors were less likely than others to have adopted a physically active lifestyle. It’s a shocking finding since regular activity is recommended to lower risk of both cancer development and recurrence.

In addition to a dearth of activity, half of the cancer survivors surveyed were overweight or obese, putting them at higher risk of cancer recurrence with poorer chances of survival. Other studies have also revealed similar findings, namely that cancer survivors often retain weight, activity and eating habits that put them at risk. This data may reflect a lack of education among cancer patients about how their lifestyle can influence future health outcomes. But it also helps to remind us that habits don’t automatically improve even after a major health scare.

A report published just this year on promoting healthy lifestyles among cancer survivors notes that studies show few differences in health behavior between adults who have had and have not had cancer. With more than half of all American adults struggling with their weight, many patients are overweight at the time of diagnosis, which can impact their survival.

Furthermore, although unwanted weight loss and poor nutrition can be serious problems among some cancer patients, overweight is a much more widespread problem among cancer survivors. Weight gain is common during and after treatment for many cancers. In a study released in October 2007, chemotherapy was shown to significantly increased odds of weight gain among more than 3000 survivors of both pre- and post-menopausal breast cancer; only 10 percent of the women studied had returned to their pre-diagnosis weight six years later. Increased fat mass has been shown to decrease one’s ability to carry out normal life activities as well as increase risk of heart disease, diabetes and possibly cancer recurrence.

Survivors of breast cancer are among the most widely studied. In the ongoing landmark Nurses’ Health Study, (non-smoking) breast cancer survivors who gained up to 14 pounds were shown to be 40 percent more likely to face recurrence than those who maintained their weight. Survivors who gained an average of 20 pounds faced a 53 percent increased recurrence. Weight gain was also linked to higher overall mortality.

More large well-controlled studies are needed, but several studies suggest that exercise can help decrease recurrence and increase survival. Cancer patients may be particularly likely to develop “sarcopenic obesity” in which muscle tissue is reduced, making weight control even harder; this makes exercise particularly important. Survivors should discuss activity with their physician, however, since some side effects of treatment may pose certain exercise risks.

Physical activity also improves overall fitness and reduces fatigue, depression and pain that affect quality of life. A 2007 study from the University of Southern California reported that 41 percent of breast cancer survivors stated that fatigue was still affecting quality of life two to five years after diagnosis. According to a recent 2008 review, appropriate exercise interventions can decrease fatigue during and after cancer treatment.

While some might assume that cancer survivors would be more motivated to change unhealthy habits and become models for healthy living, sustained change is hard – for everyone. Overall, studies suggest that cancer survivors tend to make few if any improvements in eating or activity habits or make changes within the first year after diagnosis but fail to maintain them.

In the past, we’ve had little evidence on which to base advice for cancer survivors. More research is needed, but emerging evidence points to the critical role that exercise, diet and weight maintenance play in preventing cancer recurrence and improving quality of life in survivors.