Surveillance of Complex Renal Cysts

One third of individuals aged >60 years will be diagnosed with at least one renal cyst following abdominal imaging. These cystic lesions are categorized according to the Bosniak classification which categorizes cysts according to their degree of complexity and risk of malignancy. Growing evidence suggests that a significant proportion of Bosniak III and IV cysts are benign and that the malignant ones present low metastatic potential. Since renal surgery carries substantial morbidity (20%) and potential mortality (0.5%), active surveillance has gained attention as a potential tradeoff to surgery to overcome overtreatment. Therefore, prospective studies of long-term follow-up are needed to confirm the oncologic outcomes of this strategy for Bosniak III/IV cysts. We first designed a pilot study that will assess the feasibility of a subsequent larger multicenter observational study aiming to ascertain mid-term safety of active surveillance. The objectives of this pilot study are a) Determining patients and urologists buy-in and barriers to the proposed intervention; b) Collecting perceptions and concerns of patients and urologists; c)