We identified overweight as an independent prognostic marker of improved cancer specific survival in patients with organ-confined but not advanced RCC. Basic research is required to resolve the dilemma of why, if a higher BMI predisposes to RCC, it concurrently prolongs survival after patients have undergone (partial) nephrectomy.

Even though pRCC and ccRCC differ significantly in many aspects including histology and genetic alterations, their long term prognosis is comparable. As we could not confirm a favourable clinical course for pRCC in general, standardised aftercare programmes and-if necessary-systemic treatment, especially in the era of novel targeted drugs, are also needed for this common RCC subtype.

We were able to identify overweight as an independent prognostic marker of improved tumor-specific survival in patients with organ-confined RCC. Basic research is required to resolve the dilemma of why, if a higher BMI predisposes to RCC, it concurrently prolongs survival after patients have undergone (partial) nephrectomy.

Objectives: To assess the impact of overweight on prognosis of renal cell carcinoma patients. Patients And Methods: A total of 2030 patients who underwent surgery for renal cell carcinoma from 1990 to 2011 in three University Medical Centers were included in this retrospective analysis. For all patients, height and weight measurements at the time of diagnosis were available for review. The median (mean) follow up was 56.6 months (66.0 months). Results: A low body mass index was significantly associated with poor tumor differentiation, histology, microscopic vascular invasion and metastatic disease at the time of diagnosis. A lower-than-average body surface area -stratified according to the European average for men (1.98 m 2 ) and women (1.74 m 2 ) -was significantly related to older age, poor tumor differentiation, the histological subtype and microscopic vascular invasion. In addition, a low visceral fat area calculated in a subgroup of 133 evaluable patients was associated with a higher risk of advanced disease (pT3-4 and/or N/M+) at diagnosis. The tumor-specific 5-year survival rate was 71.3, 78.7 and 80.1%, for patients with a body mass index of, <25, 25-30 and Ն30. Multivariate analysis confirmed body mass index as an independent prognostic factor. Conclusion: Our findings suggest that overweight represents an independent prognostic factor in renal cell carcinoma patients. Further research should address the question of why obese people have a higher incidence of renal cell carcinoma, but at the same time a significantly better prognosis than other patients, particularly in the case of localized disease.

Facing the results of this large trial, we do not support the inclusion of UCS invasion into upcoming TNM staging systems. In contrast, future research should focus on novel molecular markers expressed by the tumor and/or specific immunological characteristics of patients with RCC which could improve prediction of RCC-associated prognosis.