[Renal cell carcinoma of patients younger than 40 years old]

Clinical and pathological characteristics of renal cell carcinoma (RCC) of patients younger than 40 years old are not well known. The objective of this study was to analyze these characteristics by comparison to a group of patients aged 58 to 62.

Retrospective study of a group of patients aged less than 40 years old (group 1, n=44) and a group of patients aged 58 to 62 years old (group 2; n=106) treated surgically for a renal mass from January 2000 to July 2009. A comparative analysis of clinical, pathological characteristics and of cancer-specific survival was performed. Specific survival was calculated with the Kaplan-Meier method and compared with the Log-Rank test. Univariate and multivariable analysis were performed to assess and quantify the effect of age on cancer-specific survival. Covariates were gender, age group, tumor size, pT stage, histological sub-type and Fuhrman grade.

Clinical and pathological characteristics were similar in both groups (P>0.05) except for histological sub-type (56% of clear cell RCC for group 1 versus 82% for group 2). In the group of patients younger than 40 years, translocation RCC represented 23% of all RCCs. Cancer-specific survival at five years was similar in both groups (80% and 76% for group 1 and 2 respectively, P>0.58). Fuhrman grade was the only independent prognostic factor of cancer-specific survival (P=0.001).

Patients younger than 40 years were more likely to have a translocation RCC than their older counterparts for who clear cell RCC represented the main histological sub-type. Cancer-specific survival was similar between both groups. Only a systematic specific immunostaining for TFE3 or TFEB will allow to assess the exact incidence and prognosis of this entity.