Diagnosis and treatment of small renal masses: the role for molecular biology.

Renal cell carcinoma (RCC), the most common type of kidney cancer, is increasing in incidence and is the most lethal genitourinary cancer. Due to the increasing use of abdominal imaging, incidentally detected, asymptomatic small renal masses (SRMs), most of which are RCC, have become the most common presentation of kidney cancer. Most RCC SRMs initially grow slowly or not at all, but others progress to advanced and metastatic cancer. Several diagnostic and prognostic genomic, transcriptomic and proteomic studies have been completed in RCC, however signatures for SRM progression have not been identified. In the absence of useful factors to distinguish those tumors requiring treatment for progression from those that can be managed by active surveillance alone, most SRMs are treated as RCC with surgery. Currently, the only prognostic factor at diagnosis is tumor size. Tumor growth rate also appears to identify potential progressive tumours. Identifying signatures for progression and the utilization of needle biopsies will be important for SRM patients and will guide therapy.