Recommendations for the Management of Rare Kidney Cancers.

Context: The European Association of Urology Renal Cell Carcinoma Guideline Panel recently conducted a systematic review of treatment options for patients with advanced non-clear-cell renal cell carcinomas (RCCs), which showed a substantial lack of evidence for management recommendations.

Objective: To improve the outcomes of patients with rare kidney cancers (RKCs), we performed a subsequent unstructured review to determine current treatment strategies and druggable pathways, involving key stakeholders with a global perspective to generate recommendations.

Evidence Acquisition: Based on the systematic review, literature was queried in Pubmed, Medline, and abstracts from proceedings of European Society for Medical Oncology and American Society of Clinical Oncology, in addition to consulting key opinion leaders and stakeholders. A conventional narrative review strategy was adopted to summarize the data.

Evidence Synthesis: The systematic review showed an absence of evidence for treating RKCs, with data only supporting sunitinib or MET inhibitors for some specific subtypes. However, a growing body of evidence implicates druggable pathways in specific RKC subtypes. To test hypotheses, the small patient numbers in each subtype require coordinated multicenter efforts. Many RKC patients are currently excluded from studies or are not analyzed using subtype-specific parameters, despite their unmet medical need.

Conclusions: We recognize the need for additional multicenter studies and subtype-specific analyses; however, we present management recommendations based on the data available. Web-based tools facilitating subtype-specific global registries and shared translational research resources will help generate sufficient data to formulate evidence-based recommendations for guidelines.

Patient Summary: Patients confronted with rare kidney cancers are often treated the same way as clear-cell renal cell carcinoma patients, despite little evidence from randomized trials. Molecular characterization of tumors to stratify patients may improve outcomes. Availability of potential agents and trials remain a problem. Collaboration among medical centers is important to pool scarce data.