April 21, 2008
The New York Times

Surviving Cancer Doesn’t Lead to Healthier Lifestyle

Most cancer survivors are just as overweight and inactive as everyone else, a new study shows.

An analysis of data collected from more than 114,000 adults in Canada shows that overall, a cancer diagnosis doesn’t appear to prompt significant changes in eating habits or increase physical activity, according to a report in Cancer, the medical journal of the American Cancer Society. The big exception is men who survive prostate cancer, who appear to be far more active than similar men without cancer.

But the overall findings are troubling because studies have suggested that cancer patients have much to gain from a healthful lifestyle. Obesity and physical inactivity are linked with a lower quality of life among cancer survivors and may increase the risk of the cancer coming back or death from the disease.

"These findings tell us that we need to look at ways to better support cancer survivors to become more active and to maintain a healthy body weight," said Kerry Courneya, professor at the University of Alberta in Edmonton. "We know that physical inactivity and obesity are risk factors for developing cancer. These are also risk factors for the recurrence of cancer. Lifestyle is just as important after diagnosis."

The researchers compared data on activity and weight to national averages among the Canadian population. There were surprisingly few differences, suggesting that a cancer diagnosis doesn’t necessarily encourage more healthful living. The main exception was among prostate cancer survivors, who were 27 percent more likely to be active and about 30 percent less likely to be obese than the general population. The study authors didn’t have an explanation for the difference except that men may have been influenced by recent studies suggesting a link between exercise and better quality of life for prostate cancer survivors.

However, it’s not clear if the lower body mass index among prostate cancer survivors is a good thing because some data suggest prostate cancer treatments can lead to loss of lean body mass.

Other findings of the study showed:

• About 21 percent of cancer survivors are physically active, compared to about 25 percent of Canadians in general.
   
• Among cancer survivors, about 18 percent are obese and 34 percent are overweight. By comparison, about 15 percent of Canadians overall are obese and 37 percent are overweight.
   
• Male cancer survivors were more likely to be overweight or obese than female cancer survivors (62 percent versus 47 percent).
   
• The lowest levels of physical activity were among colorectal cancer survivors, breast cancer survivors and female melanoma survivors.
   
• Male skin cancer survivors were more active than the rest of the population, but that difference may simply reflect the fact that active people who spend a lot of time outdoors are more likely to develop skin cancer.