De Novo Kidney Graft Tumors: Results From a Multicentric Retrospective National Study

Abstract

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.

The High Rate of de novo Graft Carcinomas in Renal Transplant Recipients

“…Eight cases of de novo carcinomas occurred in the allograft, which is much higher to the reference study [6]. The incidence was 0.19% in this series, which is lower than our 0.78% incidence (4-fold).…”

“…Hetet et al [21], in a review of the literature, found that the proportion of these histological types of kidney graft cancers was similar to those in native kidney cancers, namely 20–30%. However, in our series, papillary carcinomas represented more than 50% of the tumors as previously reported [6]. …”

“…The diagnosis was made using routine US or CT. As reported, similarly to native kidney tumors, when kidney graft tumors were symptomatic (graft-related pain, hematuria) they had a worse prognosis [6]. We could not confirm this finding as our recipients had no symptoms or change in creatinine related to graft tumors.…”

“…For kidney graft tumors, nephron-sparing surgery remains the rule, depending on tumor size and location [6]. Nephron-sparing surgery seems to be a safe procedure that allows an acceptable quality of life, avoiding immediate dialysis, but at risk of hemorrhage and urine leakage.…”

“…These tumors can arise under three circumstances: renal carcinoma transmitted by the donor, de novo malignancies arising in the recipient after transplantation with a functional or a nonfunctional graft. De novo cancers arising in kidney grafts are rarely described in the literature and their prevalence is probably underestimated [5] despite a recent study [6]. Extending our knowledge on the occurrence of de novo graft tumors in RTRs may ultimately lead to better patient management.…”