DaPeCa5 – obesity at the time of diagnosis does not predict poor cancer-specific survival in patients with penile squamous cell carcinoma – a Danish National study

Abstract

Background

Conflicting data on the prognostic significance of obesity in penile cancer have been presented in recent years.

Objective

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.

Methods

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.

Results

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.

Conclusion

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.

Keywords:

• Penile cancer
• squamous cell carcinoma
• obesity
• prognosis
• weight loss
• mortality
• cause specific survival

Acknowledgements

The authors wish to thank Professor Steen Walter for reviewing the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).