National survey data from the United Kingdom indicate that around 23 percent of all women in England are obese and 34 percent are overweight. Obesity is known to be associated with excess mortality from all causes combined, but less is known about its effects on cancer.
So Cancer Research UK researchers at Oxford University examined the relation between body mass index (BMI), cancer incidence and mortality in 1.2 million UK women aged between 50 and 64. Risks for all cancers, and for 17 specific types of cancer, were measured according to BMI and women were followed up for an average of 5.4 years for cancer incidence and 7 years for cancer mortality. Women with a BMI of 25 to 29.9 were defined as “overweight” and women with a BMI of 30 or more as “obese,” in accordance with the World Health Organisation’s criteria.
Results were adjusted for factors such as age, socioeconomic status, smoking status, alcohol intake and physical activity. A total of 45,037 new cancers and 17,203 deaths from cancer occurred over the follow-up period. Increasing body mass index was associated with an increased incidence of all cancers combined and for ten out of the 17 specific types of cancer examined: endometrial cancer, adenocarcinoma of the oesophagus, kidney cancer, leukaemia, multiple myeloma, pancreatic cancer, non-Hodgkin’s lymphoma, ovarian cancer and, in some age groups, breast and colorectal cancer. In general, the relation between body mass index and mortality was similar to that for incidence.
Based on these results, the authors estimate that, among postmenopausal women in the UK, 5 percent of all cancers (about 6,000 annually) are attributable to being overweight or obese. But the impact of being overweight or obese on cancer risk was much bigger for some cancers than for others. For endometrial cancer and adenocarcinoma of the oesophagus in particular, body mass index represents a major modifiable risk factor, as about half of all cases are attributable to overweight or obesity, they conclude.
MEDICA.de; Source: British Medical Journal