SOURCES: Arun Swaminath, M.D., director, inflammatory bowel disease program, Lenox Hill Hospital, New York City; Jules Garbus, M.D., colorectal surgeon, Winthrop-University Hospital, Mineola, N.Y.; Kaiser Permanente, news release, May 19, 2016
THURSDAY, May 19, 2016 (HealthDay News) -- In what may come as a bit of a surprise, a new study found that overweight colon cancer patients tended to have better survival than their normal-weight peers.
"Overweight and obesity have been identified as risk factors for many health conditions, but for people with colorectal cancer, some extra weight may provide protection against mortality," said study lead author Candyce Kroenke. She's a research scientist at Kaiser Permanente Division of Research in Oakland, Calif.
Still, one health expert cautioned that the finding is no license for people to pile on excess pounds.
"This study should not be used to describe an 'upside' of being overweight with regard to cancer risk, since overweight people develop cancer at higher rates," said gastroenterologist Dr. Arun Swaminath of Lenox Hill Hospital in New York City.
In the study, Kroenke's team examined the medical records of more than 3,400 people in California diagnosed with stages 1-3 colon cancer between 2006 and 2011. The researchers then compared each patient's risk of death at the time of diagnosis and then over the following 15 months.
Patients who were either underweight or statistically obese at diagnosis were more likely to die than normal-weight patients, the study found.
However, people who fell into the "overweight" -- but not obese -- category were 55 percent less likely to die from colon cancer and 48 percent less likely to die from any cause than normal-weight patients, the research team found.
Prior research has shown that overweight and obese people are at higher risk for several types of cancers. However, they often have better cancer outcomes than normal-weight patients, something referred to as the "obesity paradox," the researchers noted.
"Our study, which represents the largest cohort of colorectal cancer patients with the most comprehensive data regarding patient weight before, at time of, and following diagnosis, supports the notion of the 'obesity paradox,' " Kroenke said in a Kaiser news release.
This is an observational study, however, so it cannot prove that weight helped cause (or shield against) death in these patients.
Also, the study "doesn't explain why this is true," noted Swaminath, who directs the inflammatory bowel disease program at Lenox Hill.
Another expert said the information is important, but shouldn't be overgeneralized.
"I feel that this study reinforces the fact that colorectal cancer treatment needs to be individualized for each patient," said Dr. Jules Garbus, a colorectal surgeon at Winthrop-University Hospital, in Mineola, N.Y.
"However, it should be said that practitioners must exercise caution when discussing any 'benefits' of overweight with patients, as there is much stronger data to support the dangers of obesity on overall health and well-being," he said.
The study was published May 19 in the journal JAMA Oncology.
The American Cancer Society has more about colon cancer.