Renal cancer subtypes: Should we be lumping or splitting for therapeutic decision making?

The treatment of advanced renal cell carcinoma has posed a challenge for decades, in part because of common themes related to intrinsic resistance to cytotoxic chemotherapy and the obscure biology of these cancer types. Forward movement in the treatment of the renal cell carcinomas thus can be approached in 2 ways: by splitting the tumor types along histologic and molecular features, in the hopes of coupling highly precision-focused therapy on a subset of patients who have disease with the most potential for benefit; or by lumping the various biologies and histologies together, to include the rarer renal cell carcinoma types with the more common types. The former strategy satisfies the desire for customized precision in treatment delivery, whereas the latter strategy allows clinicians to offer a wider therapeutic menu in a set of diseases we are continuing to learn about on a physiologic and molecular level. Cancer 2017;123:200-209.