Obesity management--an opportunity for cancer prevention.
There is increasing evidence of an association between obesity and the development, morbidity and mortality of cancers of the colorectum, (post menopausal) breast, endometrium, kidney, pancreas and oesophagus. In addition to obesity per se, waist circumference is now emerging as a clear indicator of disease risk. Weight gain during adult life also appears to increase risk for breast and colon cancers. Major causative factors which are influenced by excess energy storage include hormones involved in metabolic control (insulin and leptin), cell growth (IGF-I and IGF-binding proteins) and reproduction (steroids and leptin). In addition, raised oestrogens are likely to contribute to the greater risk of breast and endometrial cancers. In cancer survivors, there are also strong indications that being overweight increases the risk for recurrence and reduces the likelihood of survival. Whilst there are no robust data testing the effect of weight loss on recurrence, current guidance highlights that normal weight, overweight and obese patients should avoid weight gain and that a modest weight loss of 5-10% is likely to have significant health benefits. Two studies have now reported long-term effects of obesity surgery on cancer risk (in addition to reducing metabolic disorders and type 2 diabetes). It is becoming increasingly clear that multi-disciplinary groups (including surgeons) are needed to identify, monitor and evaluate programmes for both obesity prevention and management.