Effectiveness and Harms of Using Kidneys with Small Renal Tumors from Deceased or Living Donors as a Source of Renal Transplantation: A Systematic Review

Context: Kidney transplantation is the best treatment for patients with end-stage renal disease. Incidence of small renal masses (SRMs), which most frequently are renal cell carcinomas (RCCs), is highest in patients aged >60 yr. The increasing age of donors can lead to the diagnosis of a higher number of SRMs when assessing the patient for transplantation, and so can theoretically decrease the number of kidneys suitable for transplantation. Aiming to increase the pool of kidneys suitable for transplantation, a number of studies have reported their experience using kidneys with SRMs for transplantation.

Objective: To systematically review all available evidence on the effectiveness and harm of using kidneys with SRMs as a source of transplantation.

Evidence acquisition: A computerized bibliographic search of the Medline, Embase, and Cochrane databases was performed for all studies reporting outcomes of adult renal transplantation using kidneys with SRMs.

Evidence synthesis: Nineteen studies enrolling 109 patients were included and synthesized narratively. The mean recipient age was 44.2 yr, and kidneys used were retrieved from living donors in 86% (94/109) of cases. Tumor excision was performed ex vivo in all cases except for two. The vast majority of excised tumors were RCCs (88/109 patients), and clear-cell subtype was most common. The mean tumor size was 2cm (range 0.5-6.0cm) and tumor grade was G1-G2 in 93% (75/81) of patients. With a mean follow-up of 39.9 mo, overall survival rates at 1, 3, and 5 yr were 97.7%, 95.4%, and 92%, respectively, and the mean graft survival rates 99.2%, 95%, and 95.6%, respectively. Only one local relapse occurred 9 yr after transplantation, which was managed conservatively. Functional outcomes, although infrequently reported, appear to be similar to those of conventional transplants, with 1.6% of these patients needing reoperation.

Conclusions: The current literature, although with low-level evidence, suggests that kidneys with excised SRMs are an acceptable source of transplantation without compromising oncological outcomes and with similar functional outcomes to other donor kidneys.

Patient summary: Renal transplantation using a kidney with a small renal mass does not appear to increase the risk of cancer recurrence and can be a good option for selected patients after appropriate counseling and allocation.