Tell me the size of your waist and I will tell you if you are in risk of prostate cancer

Visceral fat, which is the fat found around our organs, is associated with increased danger of prostate cancer say scientists in today issue of Obesity Research.

For a long time abdominal obesity has been associated with an increase in cardiovascular diseases, diabetes, hypertension 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. A clear example of this relationship is the increase in prostate cancer among Japanese men emigrating to the United States from Japan (where the disease is still rare).

Pedro Von Hafe, Henrique Barros and colleagues from the Faculty of Medicine of Porto and the Hospital of São João, Porto, Portugal hypothesised that previous inconclusive results, found when studying the relationship between fat and prostate cancer, were due to the fact that the existence of different types of adipose tissue was never taken into account. And 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 our vital organs and is much more harmful than subcutaneous adiposity. In fact, visceral fat is known, for example, to predispose to cardiovascular and metabolic problems although the mechanism(s) by which these complications appear is still not known.

Von Hafe, Barros and colleagues in order to understand the contribution of different types of adipose tissue to prostate cancer used computerized axial tomography, a technique that employs advanced x-ray technology and allows to distinguish, and individually measure, different types of adipose tissue. The team of scientists compared sixty-three prostate cancer male patients with sixty-three healthy controls from the same sex and ethnical background and with similar age, height and weight. Very interestingly, it was found that higher quantities of visceral fat, but not of subcutaneous fat, were associated with prostate cancer. This result corroborates the researchers ’ hypothesis that different fat have different effects in prostate cancer incidence. 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, contributing for the harmful effect of visceral fat is the fact that this type of adiposity tends to be metabolised by the liver into fatty acids and released into the blood what will ultimately lead to an increase of insulin in the blood. And insulin is known to be capable of induce the growth of cancerigenous cells, including cells from prostate tumours.

Von Hafe, Barros and colleagues’ work is important because it alerts to the importance of distinguish between different types of fat when calculating individual obesity levels and their potential risk to health. Furthermore, comprehension of the mechanisms leading to prostate cancer is the first step for disease prevention.

Piece researched and written by: Catarina Amorim (catarina.amorim@linacre.ox.ac.uk)