Obesity raises prostate cancer risk

Abdominal obesity has long been associated with an increase in heart-related conditions and some types of cancers but until now, it has not been possible to establish a relationship between prostate cancer and weight, even if evidence supports the idea that environmental factors, such as western diet and life style, affect the incidence of the disease.

But a new study, published in the December issue of Obesity Research​ (pp1930-5), shows that visceral fat, or the fat found around organs, is associated with increased danger of prostate cancer.

The finding has major implications given today's rise in obesity. Almost one third of people living in the European Union are overweight and more than one in ten is now obese, according to European Association for the Study of Obesity.

Moreover the number of children who are overweight is set to rise from 20 per cent to 25 per cent by 2008.

The study also shows that risk of obesity-related disease depends on types of fat.

Different types of fat tissue, because they possess different types of metabolism that produce different biochemical substances, affect the body in very different ways.

Adipose tissue in the human body comes in two types: subcutaneous fat which is located just below the skin, and visceral fat, which is located, unnoticed, below the muscles surrounding vital organs.

This fat is considered much more harmful than subcutaneous adiposity as it is known to predispose to cardiovascular and metabolic problems, although the mechanism(s) by which these complications appear is still not known.

Pedro Von Hafe, Henrique Barros and colleagues from the Faculty of Medicine of Porto and the Hospital of São João, Porto, Portugal used computerized axial tomography, a technique that employs advanced x-ray technology and allows to distinguish, and individually measure, different types of adipose tissue.

They compared 63 prostate cancer male patients with the same number of healthy controls from the same ethnical background and with similar age, height and weight.

It was found that higher quantities of visceral fat, but not of subcutaneous fat, were associated with prostate cancer. The quantity of visceral fat, however, did not correlate with the disease stage, indicating that once established, other factors contribute to the evolution of disease.

The different results found between visceral and subcutaneous fat, probably result from different biochemical substances produced by each of the adipose tissue, which will affect the body in different ways.

Furthermore, the researchers note that visceral fat tends to be metabolised by the liver into fatty acids and released into the blood, ultimately leading to an increase of insulin.

Insulin is known to be capable of inducing the growth of carcinogenic cells, including cells from prostate tumours.