Image-guided minimally invasive treatment for small renal cell carcinoma

Renal cell carcinoma (RCC) is among the ten commonest tumours among both males and females in the western world [ 1 ]. The increased incidental detection rate of small asymptomatic renal tumours is a result of the higher number of cross-section scans that are performed for other reasons [ 2 ]. More than 80% of those small renal masses (SRMs) have proved to be cT1a (maximum diameter smaller than 4 cm) renal cell carcinomas (RCCs) [ 3 ]. The management of such small lesions generates significant controversy; the potential options are active surveillance and nephron-sparing treatments with either surgery or ablation [ 4 , 5 ]. Indications for treatment may be absolute (i.e. patients with only one anatomical or functional kidney) or relative (i.e. patients with hereditary forms of renal cell carcinoma, functioning opposite kidney that is affected by a disorder that might impair renal function in the future) [ 6 , 7 ]. Surgery has evolved from open radical to partial nephrectomy (PN) and the latter may be performed as open, conventional laparoscopic or robot-assisted laparoscopic. Nephron-sparing surgery in tertiary care centres may offer a 5-year survival of up to 90% with satisfactory preservation of renal function and reduction of the frequency of cardiovascular events in comparison to the radical excision [ 8 , 9 , 10 , 11 ]. Active surveillance (AS), on the other hand, has been historically reserved for those patients who may be unfit for surgery. The concept of AS is based on the fact that the growth rate of the majority of these tumours is relatively slow (2-3 mm/year) and the metastatic potential is also, in general, rather low. However, given that there are currently no biomarkers that may predict the natural history of such masses, close monitoring with cross-sectional imaging is required in order to detect those tumours that will grow rapidly [ 12 , 13 , 14 ]. Furthermore, the Swedish Kidney Cancer Quality Register has highlighted that there is a more significant metastatic potential than what is generally believed, even for tumours that are between 1 and 4 cm [ 15 ].