Colon cancer more deadly for large-waisted women

Colon cancer more deadly for large-waisted women By Reuters Health September 10, 2010 NEW YORK (Reuters Health) – Older women with bulging bellies are at greater risk of dying from colon cancer after being diagnosed with the disease than those with trimmer waists, new research shows. Mortality due to any cause was also higher among extremely thin women and obese women with colon cancer, Dr. Anna E. Prizment of the University of Minnesota in Minneapolis and her colleagues report in the journal Cancer Epidemiology, Biomarkers and Prevention. “Our findings provide another reason for postmenopausal women to keep their weight, waist, and WHR (waist-to-hip ratio) within normal limits throughout their life,” Prizment told Reuters Health. “Doing so may not only reduce incidence of colon cancer but also increase survival if colon cancer occurs later in life.” Several studies have shown that people who carry more fat around their waist are more prone to developing colon cancer, and that risk also climbs as body mass index (BMI, a measure of weight in relation to height used to determine if a person is overweight or obese) rises, Prizment and her team write. There’s also strong evidence that heavier people diagnosed with colon cancer are more likely to die from the disease. However, the researchers add, less is known about how a person’s weight status before colon cancer diagnosis relates to their survival after being diagnosed with the disease, and about whether a person’s waist circumference might be a better gauge of mortality risk than their overall BMI. To investigate, the researchers looked at data on 1,096 postmenopausal women who developed colon cancer during the course of the Iowa Women’s Health Study, an ongoing study of cancer risk factors in more than 40,000 older women. They followed participants from the study’s outset, in 1986, through 2005. Over the 20-year follow-up period, 493 of the women died, 289 of whom died from colon cancer. Colon cancer patients with prediagnosis BMIs of 30 or above, indicating obesity, were 45% more likely to die from any cause during follow-up than normal-weight patients (BMI between 18.5 and 24.9). The handful of women who were very underweight — just 11 had BMIs below 18.5 — had nearly double the risk of dying from any cause compared to normal-weight women. Other studies have shown similarly increased risks for very thin women, Prizment noted. “They are usually frail, do not tolerate treatment well, and are prone to infections,” the researcher said. While there wasn’t a significant relationship between BMI and likelihood of dying from colon cancer, waist size and its relation to hip size did matter, the researchers found. Women with waists measuring more than 32.4 inches were 34% more likely to die of colon cancer during follow-up, whereas those in the top third based on the size of their waists in relation to their hip size (meaning they were the most “apple-shaped,” versus being “pear-shaped”) were at 37% higher risk. Overall, about one-third of people diagnosed with colon cancer will die of the disease within the next 20 years, according to one estimate. Based on that statistic, having a large waist-to-hip ratio would increase a female colon cancer patient’s 20-year risk of dying of the disease to 45%. About 143,000 new cases of colon cancer are diagnosed in the U.S. each year, some 70,500 of them in women. There are a number of ways that obesity and abdominal fat could increase colon cancer mortality, Prizment noted. Fat that gathers at the abdomen produces hormones and other substances that can increase resistance to the key blood-sugar-regulating hormone insulin, promote inflammation, and possibly foster the development of colon cancer, the researcher explained. “More consistent associations have also been found for increased waist circumference and WHR than for BMI in relation to the risk of colon cancer,” she added. “At this time, we do not know if lowering weight or waist after colon cancer diagnosis can improve survival or not,” Prizment said. “More prospective and intervention studies with detailed information on tumor characteristics, treatment, and comorbidities, are needed to examine the effect of obesity, and especially abdominal obesity, measured before and after colon cancer diagnosis.” By Anne Harding Source: Cancer Epidemiology, Biomarkers & Prevention, September 2010. Last Updated: 2010-09-09 16:20:02 -0400 (Reuters Health)