Management of Renal Cell Carcinoma of Variant Histology
摘要
Renal cell carcinoma is a histologically heterogeneous disease, with multiple subtypes each with varying underlying mechanisms of tumorigenesis. Clear cell renal cancer is the most common histology accounting for approximately 75% of tumors. The remaining 25% of renal malignancies are coined under an umbrella term known as variant histology or non-clear cell renal cell carcinoma. Papillary renal cell carcinoma (10–15%) represents the most common variant histology, with chromophobe renal cell carcinoma (5%), collecting duct renal cell carcinoma (1%), translocation renal cell carcinoma (1%), renal medullary carcinoma (<1%) among other rare types making up the remainder. Given the heterogeneity of the tumor types and the rarity of each disease, a prospective study of each subtype is challenging. The limited representation of variant histology renal cell carcinomas in large phase III randomized trials lends to uncertainty regarding the benefit of specific therapies in this group, and most treatments employed in the variant histology space are extrapolated from prior success in patients with clear cell renal cell carcinoma. Although anti-vascular endothelial growth factor (VEGF) agents, mammalian target of rapamycin (mTOR) inhibitors, and immune checkpoint inhibitors (ICIs) have made a large impact in the management of advanced clear cell renal cell carcinoma, their efficacy in variant histologies is still being defined. As we continue to learn more about these tumor types at a molecular level, new subtypes of kidney cancer and new genetic abnormalities are being discovered. This improved understanding can lead to better treatments in the future for our patients.