Obesity may be partly to blame for rising rates of renal cell cancer

Review of: Pischon T, Lahmann PH, Boeing H, Tjonneland A, Halkjaer J, Overvad K, Klipstein-Grobusch K, Linseisen J, Becker N, Trichopoulou A, Benetou V, Trichopoulos D, Sieri S, Palli D, Tumino R, Vineis P, Panico S, Monninkhof E, Peeters PH, Bueno-de-Mesquita HB, Buchner FL, Ljungberg B, Hallmans G, Berglund G, Gonzalez CA, Dorronsoro M, Gurrea AB, Navarro C, Martinez C, Quiros JR, Roddam A, Allen N, Bingham S, Khaw KT, Kaaks R, Norat T, Slimani N, Riboli E. Int J Cancer 2006;118(3):728-738.

The previously suggested relationship between the incidence of renal cell cancer (RCC) and obesity was recently further investigated in an epidemiological European multicentre study.
The incidence of RCC is increasing worldwide with an estimation of about 81,000 new cases per year in Europe, including the Eastern European countries, accounting for 2.9% of all cancers. Dr. Tobias Pischon and collaborators examined the association between anthropometric measures, including waist and hip circumference and RCC risk in 348,550 participants from 8 countries of the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Incident RCC cases were identified by population cancer registries (Denmark, Italy, the Netherlands, Spain, Sweden, the United Kingdom) or by active follow-up (Germany, Greece), depending on the follow-up system in each of the participating centers. During the six years of follow up, 287 (of which 132 female) incident cases of RCC were identified.

Relative risks were calculated using Cox regression, stratified by age and study centre and adjusted for smoking status, education, alcohol consumption, physical activity, menopausal status, and hormone replacement therapy use. Among women, an increased risk of RCC was conferred by body weight, body mass index (BMI), waist and hip circumference; however, waist and hip circumference were no longer significant after controlling for body weight. Among men, hip circumference was related significantly to decreased RCC risk only after accounting for body weight.

In the discussion, the authors bring up a number of potential mechanisms underlying the relation between obesity and increased RCC risk. Increased circulation levels of insulin and insulin-like growth factor 1 (IGF-1) which are frequently found in adipositas, have been related to carcinogenesis and furthermore, there is a well established association between obesity, hypertension and diabetes, two known risk factors for RCC.

In conclusion, obesity seems to increase the risk of RCC among women, regardless of the fat distribution pattern, while among men, a small hip circumference is associated with increased risk. With obesity rapidly becoming a burden on our society, we need to pay more attention to early detection of RCC as well as other chronic diseases. Even better is of course if we can reduce the number of people with overweight by an extensive preventive medicine programme.

Author: Prof. Anders Bjartell

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