De novo tumors in renal allografts are rare and their prevalence is underestimated. We therefore analyzed renal cell carcinomas arising in renal allografts through a retrospective French renal transplant cohort. We performed a retrospective, multicentric survey by sending questionnaires to all French kidney transplantation centers. All graft tumors diagnosed after transplantation were considered as de novo tumors. Thirty-two centers participated in this study. Seventy-nine tumors were identified among 41 806 recipients (Incidence 0.19%). Patients were 54 men and 25 women with a mean age of 47 years old at the time of diagnosis. Mean tumor size was 27.8 mm. Seventy-four (93.6%), 53 (67%) and 44 tumors (55.6%) were organ confined (T1-2), low grade (G1-2) and papillary carcinomas, respectively. Four patients died of renal cell carcinomas (5%). The mean time lapse between transplantation and RCC diagnosis was 131.7 months. Thirty-five patients underwent conservative surgery by partial nephrectomy (n = 35, 44.3%) or radiofrequency (n = 5; 6.3%). The estimated 5 years cancer specific survival rate was 94%. Most of these tumors were small and incidental. Most tumors were papillary carcinoma, low stage and low grade carcinomas. Conservative treatment has been preferred each time it was feasible in order to avoid a return to dialysis.

Nephron sparing surgery is a safe and efficient procedure for the treatment of renal cell carcinoma in renal grafts, resulting in the preservation of renal function and in short-term cancer control.

What ' s known on the subject? and What does the study add? The renal cell carcinoma incidence among renal transplant recipients is approximately 0.5%; however, a signifi cant increase in the number of RCC in renal grafts can be expected in the forthcoming years due to the increase in donor age and in renal graft survival.Our fi ndings support evidence that radiological screening of kidney recipients allows the detection of small tumors for which a conservative management by nephron sparing surgery or nonsurgically destructive techniques can be proposed with mid-term oncological safety. Systematic tumor biopsy may also help in the management and treatment decision. OBJECTIVE• To study the natural history of renal cell carcinoma (RCC) development in renal grafts and their management. PATIENTS AND METHODS• We report a single-centre series of de novo RCC in allografts from a cohort of 2396 consecutive renal transplant recipients. RESULTS• In all, 17 RCCs were detected in 12 patients, representing 0.5% of kidney recipients.• The mean patient age was 55 years and the time to RCC diagnosis since transplantation was 13 years. The mean diameter of the RCC was 23 mm.• Biopsies were taken in all cases. Concordance between biopsy and surgical specimens was 100% for nuclear grade and pathological type.• Four graft removals were performed and six patients underwent nephron-sparing surgery (NSS). Two cryoablations were performed.• Overall, nine papillary RCC, fi ve clear cell carcinomas, and one chromophobe cell carcinoma were removed surgically. The mean follow-up was 43 months. One local recurrence was reported in a patient treated by NSS. CONCLUSIONS• Our fi ndings support evidence that radiological screening of kidney recipients allows the detection of small tumours for which a conservative management by NSS or non-surgically destructive techniques can be proposed with mid-term oncological safety.• Systematic tumour biopsy may help in the management and treatment decision.• Several questions remain unanswered such as the importance of mammalian target of rapamycin inhibitors in the chemoprevention of the recurrence and the genetic cell origin of RCC in renal grafts.

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