Unwrapping Nephrogenic Rests and Nephroblastomatosis for Pediatric Surgeons: A Systematic Review Utilizing the PICO Model by the APSA Cancer Committee.

Background: Nephrogenic rests (NR) may represent precursor lesions for Wilms tumor (WT), but their clinical course is not fully understood and no guidelines for treatment exist. This study sought to evaluate the outcomes of pediatric patients with NRs related to traditional chemotherapy and surgery.

Methods: A PRISMA-P-compliant literature search was conducted in MEDLINE, Embase, CINAHL, Web of Science, COCHRANE, and SCOPUS from inception to June 2021. Clinical questions regarding the treatment of NRs, including chemotherapy and surgery, were developed in the population, intervention, comparison, and outcome format.

Results: Twenty-five studies including 1445 patients met inclusion criteria for evaluating chemotherapy compared to observation for NRs. Eighteen studies including 1392 patients met inclusion criteria for evaluating the role of surgery for NRs. Patients with isolated NRs who underwent observation progressed to WT 33% of the time; chemotherapy reduced the rate of WT to 3.9%. Observation of multiple NRs and diffuse hyperplastic perilobar nephroblastomatosis (DHPLN) led to progression to WT 50% and 100% of the time, respectively. Chemotherapy reduced the rate of WT to 34% for multiple NRs and 46% for DHPLN. Surgery for isolated NRs reduced the risk of WT development from 23.7% in patients with incomplete excision to 3.3% with complete excision; however, 96% of patients with incompletely excised NRs had bilateral disease.

Conclusions: Observation with close surveillance for isolated NRs is safe. Treatment with chemotherapy is recommended for patients with multiple NRs and DHPLN. Surgical management of NRs should focus on renal function preservation.

Level Of Evidence: Treatment study, Level III.