Editorial Comment to Radical prostatectomy in obese patients: Improved surgical outcomes in recent years

On the one hand, prostate cancer has attracted an enormous amount of attention in the field of scientific research as well as the non-professional press. The discovery of prostate-specific antigen (PSA), public prostate awareness and shifting population age distributions towards the elderly in many populations has prioritized prostate cancer research. On the other hand, obesity is one of the most challenging and growing health problems in industrialized countries. In the USA, over the past 20 years, the prevalence of obesity among adults has doubled to 30%.1 Although obesity is less common in Europe, the prevalence has also more than doubled during the past two decades.2 In summary, it is expected that urologists will increasingly be confronted with obese men having a localized prostate cancer. The risk of obesity in developing prostate cancer is controversial.3-5 However, more agreement exists on the increased risk of biochemical recurrence in obese men who have undergone a radical prostatectomy.6-8 Of note, all studies were carried out in the USA. Several recent reports from Europe could not confirm this relationship.9, 10 In this issue of International Journal of Urology, Linder et al. from the University of Toronto also failed to show a positive link between obesity and biochemical recurrence.11 Of note, the mean follow-up was just 4.5 years and the study population consisted of 491 patients. Although not significant, the obese patients had more often positive surgical margins compared with their thinner counterparts (22% vs 11%). It is generally held that obesity makes many urological procedures technically more challenging. Positive surgical margins might a result of bad surgical technique and/or from the extension of the tumor beyond the planned limits of resection. However, in the study of Linder et al. obese patients were not at higher risk of developing biochemical recurrence. A problem of measuring obesity with body mass index is that it is a marker of general obesity. The most metabolic fat, however, is the abdominal visceral fat. In a large cohort study of 129 502 men,12 waist circumference and waist-to-hip ratio (as a measure of abdominal obesity) were positively associated with the risk of advanced prostate cancer disease. These data suggest that an increased risk of advanced prostate cancer is more strongly associated with abdominal adiposity than with body mass index. A computed tomography or magnetic resonance imaging scan are excellent techniques to distinguish and quantify subcutaneous and visceral fat. A future step would be to measure the activity of fat by collecting fat from different parts of the body (e.g. during a radical prostatectomy) and to determine the cytokine production of the fat cells collected from different locations. By linking these data with anthropometric data of the patient and its prostate cancer characteristics, a better insight might be gained in the exact role of obesity in prostate cancer. A first step is made by Finley et al.13 They recently investigated the periprostatic fat quality by analyzing the periprostatic fat and found that high levels of IL-6 correlated with tumor grade.