Renal cell carcinoma (RCC) arising in native kidneys of dialyzed and transplant patients: are they different entities?

UNLABELLED: What's known on the subject? and What does the study add? Patients with end-stage renal disease (ESRD) have an increased risk of developing RCC in their native kidneys. The prevalence of RCC is 3-4% in cases of ESRD in dialyzed and/or transplanted patients, which corresponds to a rate 100-times higher than that in the general population. This is the first study, to our knowledge, comparing the characteristics of kidney cancer in the ESRD population according to their dialysis or transplantation status at the time of diagnosis. The differences in stage and survival we observed may be due to differences in surveillance strategies between transplanted and not transplanted patients, nevertheless, the differences in pathological subtypes suggest they could also be due to differences in the tumorigenesis process.

OBJECTIVE: • To compare clinical, pathological and outcome features of renal cell carcinomas (RCCs) arising in patients with chronic renal failure (CRF) with or without renal transplantation.

PATIENTS AND METHODS: • In all, 24 French University Departments of Urology and Kidney Transplantation participated in this retrospective study comparing RCCs arising in patients with CRF according to their dialysis or transplantation status at the time of diagnosis. • Information about age, sex, symptoms, duration of CRF, mode and duration of dialysis, renal transplantation, tumour staging and grading, histological subtype and outcome were recorded in a unique database. • Qualitative and quantitative variables were compared by using chi-square and Student statistical analysis. Survival was assessed by Kaplan-Meier and Cox methods.

RESULTS: • Data on 303 RCC cases diagnosed between 1985 and 2009 were identified in 206 men (76.3%) and 64 women (23.7%). • Transplanted and not transplanted patients accounted for 213 (70.3%) and 90 cases (29.7%), respectively. • In transplant recipients, RCC was diagnosed at a younger age [mean (sd) 53 (11) vs 61 (14) years, P < 0.001), the mean tumour size was smaller [3.4 (2.3) vs 4.2 (3.1) cm, P= 0.02), pT1a stage (75 vs 60%, P= 0.009) and papillary histological subtype (44 vs 22%, P < 0.001) were more frequent than in their dialysis-only counterparts. • Nodal (1 vs 6%, P= 0.03) and distant metastases rates (0 vs 5%, P < 0.001) were significantly increased in patients who had not had a transplant. However, Fürhman grading, symptoms, tumour multifocality or bilaterality, presence of acquired cystic kidney disease, were not significantly different between the groups. • Estimated 5-year survival rates were 97% and 77% for transplanted and not transplanted patients, respectively (P < 0.001). In univariate analysis, presence of symptoms (P= 0.008), poor performance status (P= 0.04), large tumour size, advanced TNM stage (P < 0.001), high Führman grade (P= 0.005) and absence of transplantation (P < 0.001) were all adverse prognostic factors. In multivariate analysis, only T stage remained an independent predictor for cancer-related death (P < 0.001).

CONCLUSION: • RCC arising in native kidneys of transplant patients seems to exhibit many favourable clinical, pathological and outcome features compared with those diagnosed in dialysis-only patients. Further research is needed to determine whether it is due to particular molecular pathways or to biases in relation to mode of diagnosis.