Women with bulging waistlines and hips in greater risk of colon cancer?
A recent scientific study reports that in older women, carrying extra weight around the waist and hips predicts greater risk of death from colon cancer. But do women with bulging waistlines and hips need to panic about the potential risk of cancer? A closer inspection of the evidence suggests that they do not.
Researchers from the American Association for Cancer Research studied the records of 1,100 women in the health professions in Iowa who developed colon cancer over the course of 20 years. They found that women who were heavier before they were diagnosed with colon cancer were more likely to die of the disease than their thinner peers.
The scientists then looked for additional clues for cancer risk. They considered not just weight, but also body mass index, waist size, and waist-to-hip ratio. They found that the how much a woman weighed or her body mass index (BMI) was less important than waistline and hip size. Women whose waists were 37 inches or more had a 34 per cent greater risk of dying than women whose waists were 32 inches or smaller.
It helps, however, to put these findings in perspective. The Iowa Women's Health Study tracks the health and health habits of over 34,000 women. During the 20 years considered in this report, 289 women died of colon cancer. In other words, in any given year, a woman in the study had a roughly 1 in 2500 chance of dying of colon cancer.
Women who had broader waistlines or "hippier" hips had a roughly 1 in 1600 chance of dying of colon cancer in any given year. The difference is statistically significant, but very small.
Women with a BMI under 18.5 had a greater risk of dying after diagnosis with colon cancer
Moreover, recent news reports on this study leave out another key finding of the Iowan Women's Health Study: Thin women, specifically women with a BMI under 18.5 had a greater risk of dying after diagnosis with colon cancer than heavy women.
Heavier women were 34 per cent more likely to die after colon cancer diagnosis. Thinner women were 89 per cent more likely to die after colon cancer diagnosis. The researchers suggested that heavy women lose weight, but they did not make a suggestion that thin women, who were at even greater risk of death, should gain weight.
The American Association for Cancer Research study is hardly the only investigation of the relationship of waist and hip size and cancer risk. A much larger study in Europe, the European Prospective Investigation Into Cancer and Nutrition (EPIC) study, followed 386,277 women and men for five years. Like the American study, the European study found that the average annual risk of colon cancer was about 1 in 2500 for both men and women.
Also like the American study, the European study found that women and men with larger waistlines and fatter hips were more likely to develop colon cancer, although they were at no greater risk for rectal cancer. The EPIC study found that the men with the largest waists were at least 1 per cent more likely to develop colon cancer, while women with the largest waists were at least 8 per cent more likely to develop colon cancer. This study also found, however, that tall and skinny people were also at greater risk for colon tumors.
The bottom line of these stories is that no one should be dieting for fear of cancer. The studies were not designed to consider that the same underlying metabolic condition could cause both overweight (or underweight!) and cancer, and they do not establish causality, that overweight or underweight actually causes cancer. Moreover, the risk of cancer is very low--and the disease is nearly 100% treatable if caught in time through routine colonoscopy.