It is now established that partial nephrectomy (PN) represents the gold-standard treatment for localized cT1 renal tumors [1]. Owing to widespread adoption of robotic technology [2], expert surgeons in referral centers worldwide have been extending indications for nephron-sparing surgery (NSS), including even the most complex and challenging surgical scenarios, such as tumors >7 cm [3], totally endophytic tumors [4], masses with a high nephrometry score [5], [6], and multiple tumors [7]. Nephrometry scores have been developed for proper classification of tumor complexity before surgery and offer surgeons an objective tool for planning NSS [8], [9]. Tumors with a high nephrometry score represent one of the most challenging clinical situations when planning a conservative approach, for which robotic PN (RPN) in expert hands is a primary option [6]. Surgical removal of a high-complexity renal mass can potentially expose the patient to prolonged warm ischemia time (WIT), a higher rate of violations of the urinary system, and more frequent perioperative and postoperative complications in comparison to a low-complexity mass [10].

The surgical quality of NSS can be objectively evaluated as the rate of achievement of a trifecta outcome, defined as negative surgical margin status, no Clavien-Dindo grade ≥3 complications, and an estimated glomerular filtration rate (eGFR) decline of ≤30% [11], [12]. For high-complexity tumors, maximal preservation of renal function (RF) via RPN might be seriously compromised, as WIT could be long-lasting and the amount of healthy renal parenchyma to be removed might be not negligible, with a consequent unavoidable detrimental impact on trifecta achievement. Among the parameters contributing to RF preservation, WIT is the only surgically modifiable factor. Minimally ischemic approaches have been developed to maximize RF preservation [13], with the most recent strategy involving a purely off-clamp RPN approach [14].

The aim of our multicenter study was to compare perioperative and functional outcomes for off-clamp and on-clamp RPN in patients with cT1–2 localized renal tumors with a high RENAL score (≥9).