By Stephen Ornes
Monitoring your BMI may help you reduce your cancer risk
By Stephen Ornes
In the last few years, researchers have increasingly turned to a three-letter tool to measure cancer risk: BMI, which stands for body-mass index. That number is a quick calculation of body fat based on height and weight—and it might help you keep cancer at bay.
In a study published Feb. 15 in the journal Cancer, epidemiologist Michael Leitzmann, formerly of the National Cancer Institute, and his colleagues found that women with a BMI of 30 or higher face an increased risk of ovarian cancer, compared with women of normal weight. With an overall five-year survival rate of only 45 percent, ovarian cancer is one of the deadliest cancers—and one of the hardest to diagnose at an early stage.
The study by Leitzmann, who is now at the Regensburg Medical Center in Germany, joins the ranks of a burgeoning field of research that seeks to define the relationship between fat and disease. And with the exception of only a few types of cancer, the general equation is the same: High BMI equals increased cancer risk.
Different Studies, Same Conclusions
The association between obesity and cancer is much stronger than most people realize, says epidemiologist David L. Katz, the director of the Yale-Griffin Prevention Research Center in New Haven, Conn. Apart from an understanding that smoking can lead to cancer, “the prevailing attitude has always been, ‘Cancer scares the hell out of me because it can just jump out of the shadows and get me,’ ” he says. “Yes, that can happen, but by and large, cancer is a very predictable thing. The extent to which weight control affects cancer is largely underappreciated.”
Underappreciated, but not for a lack of evidence. One of the strongest connections between obesity and cancer risk arrived in a study published in the New England Journal of Medicine in 2003. After 16 years of following nearly a million individuals who were cancer-free at the outset of the trial, researchers from the American Cancer Society (ACS) found that extremely obese men—those with a BMI of 40 or higher—faced a 52 percent increased risk for all cancers combined; for women, the increase was 62 percent. The study’s authors estimated that being obese or overweight could account for 14 percent of all cancer deaths in men, and 20 percent in women.
The researchers found that when compared with a person of normal weight, a person with a BMI of 30 or higher faces at least a 20 percent increased risk of colorectal, esophageal, gallbladder, kidney, liver, pancreatic and stomach cancers, as well as multiple myeloma and non-Hodgkin lymphoma. In addition, men with a BMI of 30 or higher face a 20 percent or more increased risk of prostate cancer and leukemia, while women with such a BMI face the risk for bladder, breast, cervical and uterine cancers.