Weighing the Cancer

BMI helps figure risk for certain cancers

(RxWiki News) The scale is only part of the picture. A person's body mass index, or BMI, is just one way of weighing someone. For certain cancers, one's BMI can give a clue of the person's odds of getting cancer.

But looking at a person's BMI may not be as effective in guessing whether a person is more at risk for various cancers, new research has found.

According to the authors, the findings suggest health professionals "should consider using different weight-for-height scaling to examine the association of body size with risk of disease in different populations."

"Don't rely on BMI - Talk to your doctor."

BMI has widely been used in large populations to show whether persons are underweight, normal weight, or overweight to obese.

It is measured through a person's weight compared to his or her height in meters squared. The higher the BMI, the higher one's risk for certain cancers, according to researchers.

The study, led by Geoffrey Kabat, PhD, senior epidemiologist in the Department of Epidemiology and Population Health at Albert Einstein College of Medicine, aimed to see if how effective other measures for weight compared to height work in showing a person's risk for 19 different cancers.

Researchers looked at almost 90,000 women who were part of the Canadian National Breast Cancer Screening Study between 1980 and 2000.

The women were between 40- and 59-years-old from Canada with no personal history of cancer before being enrolled in the study. More than half were postmenopausal.

Researchers recorded their height and weight and surveyed participants on their reproductive, lifestyle and hormonal characteristics.

Another survey introduced in 1982 accounted women's portion sizes and what they ate and drank, including alcohol. The authors also kept track of the participants' demographics.

By the end of the study, 5,679 women had been diagnosed with cancer. The kinds of cancer included in the study each had at least 90 diagnoses.

Researchers found that weight-to-height ratios were significantly linked to showing a person's risk of getting lung, kidney, postmenopausal breast and endometrial cancer.

BMI however does not work in showing one's risk for premenopausal breast cancer, colorectal, leukemia, bladder, ovary, brain, melanoma and non-Hodgkin’s lymphoma cancers.

"It has long been recognized that BMI is an imperfect indicator of body fat because weight does not distinguish between lean body mass (muscle, bones, blood, water) and fat mass," Dr. Kabat said in a press release.

The authors say that future studies should look into how the findings apply to different populations; the people and the disease being studied need to be considered when choosing whether BMI is best way to measure one's body weight.

Albert Einstein College of Medicine and the Breast Cancer Research Foundation supported the study.

The authors do not report any conflicts of interest in their study, which was published online November 8 in the American Journal of Epidemiology.

Review Date: 
November 7, 2012