Conflicting data on the prognostic significance of obesity in penile cancer have been presented in recent years.
The objective of this study was to investigate obesity as a prognostic factor in patients with penile squamous cell carcinoma (pSCC) in a large national Danish cohort. Furthermore we aimed to compare the BMI of pSCC patients to a large age-matched cohort of healthy men.
We evaluated 429 patients with invasive pSCC from a national retrospective penile cancer cohort and defined a body mass index (BMI) at 30 kg/m2 as obese. Furthermore, we considered if a fitted model for BMI and mortality could define a critical BMI tipping point for increasing mortality by the means of BMI categories of 1 kg/m2 width. We compared 29 pSCC patients with reported unintended weight loss at diagnosis to 400 with no reported weight loss. Cox regression with 95% confidence intervals was used for penile cancer-specific survival analysis. The comparison between 325 age-matched pSCC patients and 11,238 healthy men from an existing contemporary health database was done by nonparametric tests.
There was no difference in cancer specific survival between patients with a BMI below and above 30 kg/m2, cox hazard ratio (HR) 0.74 (0.47-1.18), p = .20, but 37 kg/m2 was a tipping point for increasing mortality, HR = 2.10 (1.06-4.18), p = .035. Unintentional weight loss prior to diagnosis significantly predicted worse cancer specific outcome, cox hazard ratio 6.0 (3.5-10.0), p < 001 and cox hazard ratio adjusted for American Joint Committee of Cancer (AJCC)-stage at 1.8 (1.1-3.1), p = .03. Age-matched pSCC patients had a significantly higher BMI than healthy males, 28.4 ± 5.5 kg/m2 vs. 26.2 ± 3.6 kg/m2, p < .0001 and were more likely to smoke, p < .0001, and report alcohol intakes over 14 units/week, p < .0001.
In this Danish cohort, BMI above 30 kg/m2 at diagnosis does not affect prognosis, but BMI at and above 37 kg/m2 at diagnosis predicts poor prognosis. Unintentional weight loss is a predictor of high stage and poor prognosis. PSCC patients have a significantly higher BMI than age-matched healthy males.
Scandinavian journal of urology. 2020 Aug 10 [Epub ahead of print]
Jakob Kristian Jakobsen, Dennis Kortsen, Jørgen Bjerggaard Jensen
Department of Urology, Aarhus University Hospital, Aarhus, Denmark.