'Fat Hormone' Tied to Higher Colon Cancer Risk
More precancerous polyps seen in small study as body fat increased
After cross-referencing overall results, the investigators determined that men who were obese faced a 6.5 times greater risk for having three or more colorectal polyps than those who were lean (with a BMI under 25).
Obese men were also found to face an almost eight times greater risk than lean men for having at least one polyp, as opposed to none.
What's more, polyp risk seemed to rise incrementally with body fat status. Specifically, polyp risk was seen to rise by a factor of nearly three when lean men were compared to overweight men. And risk went up again by the same amount when comparing overweight men to obese men.
Importantly, the team also found that having higher levels of the fat hormone leptin was similarly associated with having a higher risk for developing polyps.
Fenton said that her previous work has already uncovered evidence for how the obesity-colon cancer connection might function.
"We found that precancer cells, like you find in a polyp, are very sensitive to leptin," she said. "And leptin increases with fat cell size and number. So in a laboratory setting and with animals we've seen that leptin makes these early cancer cells grow," Fenton explained.
"So while we can't yet add obesity to the risk profile for colon cancer, we do think we understand the mechanism behind this," Fenton noted. "And if this is confirmed in a larger population it could lead to a change in screening protocols."
Meanwhile, Lona Sandon, a registered dietitian and assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas, said that as far as she is concerned, it's never too early to start eating better and get weight under control.
"Obesity has been associated with several types of cancer, colon cancer just being one of them," Sandon said. "And so whatever the exact mechanism is behind why excess body fat seems to promote colon cancer risk, this work continues to demonstrate the importance of maintaining a healthy body weight and, therefore, eating a healthy diet."