Stage I clear cell sarcoma of the kidney: is it the time for a less intensive adjuvant treatment?

Clear cell sarcoma of the kidney (CCSK) is a rare type of renal tumor, comprising 2% to 5% of all primary renal tumors in children. Despite the label of “unfavorable” tumor, with recent multimodality treatment schedules, including radiotherapy and multi-agent chemotherapy, disease free survival rates approaching 80% can be achieved. Younger age at tumor diagnosis and advanced-stage disease represent adverse prognostic factors. Of note, as a consequence of oncologic therapies a number of surviving patients have suffered from late sequelae on the musculoskeletal, gastrointestinal, hepatic, endocrine and cardiovascular function, or developed second tumors. Improved survival rates and a deeper knowledge of iatrogenic complications have promoted the awareness of a sequential reduction of treatment intensity, at least for low-stage CCSK, above all focusing on the abolition of flank radiation therapy (RT). It is fundamental to recognize that the rarity of this tumor calls for international cooperation trough controlled clinical trials, and without forgetting the key importance of a correct histological diagnosis and adequate surgical staging. The recent recognition of CCSK specific chromosomal translocation might help to guide targeted therapies complementary to conventional chemotherapy and radiotherapy.