February 15, 2008

Added Pounds may Increase Cancer Risk

For years, doctors have hypothesized about a link between weight gain and cancers like breast and colon. A new European study published this week surmises that not only can weight gain increase risk for these types of cancer, but for many others as well, such as cancer of the thyroid, kidney, esophagus, uterus and gall bladder.

Researchers covered more than 280,000 cases from North America, Europe, Asia, and Australia, in attempts to cover more ground than previous research. These cases included more types of cancer as well as more a more diverse group of subjects.

Dr. Andrew Renehan, senior lecturer at the University of Manchester's School of Cancer Studies, says that the research is complicated; in order to find correlation between cause and effect, several things need to be carefully studied. This research study is limited, and more studies need to be done to prove associations that being fat can cause cancer.

The subjects of the study had their body mass index tracked for 9 to 15 years. The subjects were both normal weight and overweight. In the men that were studied, those who gained 33 pounds on average increased their risk of colon and kidney cancers by 24 percent, thyroid cancer by 33 percent, and esophagal cancer by 52 percent.

In the women, a 29 pound weight gain increased the risk of kidney cancer by 34 percent, esophageal cancer by 51 percent and uterine and gall bladder cancer by almost 60 percent.  Particularly in Asian populations, the link between increased BMI and breast cancer seemed stronger.

Even with all of these findings, scientists are unsure of the link between being overweight and having cancer. There are several hypotheses. One of these, Renehan said, "is that the presence of excess fat cells could affect the levels of hormones in your body. At a cellular level, that may favor the development of tumors in humans."

Although there is still currently no proof that cancer can be caused simply by just being fat, this study does provide information about the dangers of being overweight. Ed Yong of Cancer Research United Kingdom says that the primary message of the study is if you maintain proper healthy body weight, you will have a lower risk of cancer. Therefore, losing weight should decrease cancer risk.


On the Net:

The Lancet

University of Manchester