Tumour size, tumour complexity, and surgical approach are associated with nephrectomy type in small renal cortical tumours treated electively

Study Type - Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Although the benefits of nephron-sparing renal cortical tumour treatments are now widely accepted and have robust data supporting their oncological efficacy, safety, and positive effect on medium- and long-term renal function, the decision to perform partial nephrectomy (PN) remains a complex interaction between several competing factors. Various patient factors, e.g. comorbid conditions, age, body habitus, patient preference, etc. may effect this decision. Then there are the preferences of the surgeon him- or herself, including faculty with different operative techniques and surgical approaches, which may lead to one treatment decision over another. Finally, the anatomy of the tumour itself, i.e. the complexity of the tumour within the kidney and anatomical relationships within the organ, is intuitively critical to a surgeon's assessment of resectability. There is very little published data indicating which of the multitude of clinical variables have the greatest impact on the decision to perform PN. Most previous investigations into the subject have focused on either imperative or relative indications for PN (i.e. solitary kidney, bilateral renal masses, and multifocal tumours) or have used maximal tumour diameter (i.e. tumour size) alone in their assessment of the clinical variables associated with PN use.

Objective: To identify preoperative variables associated with choice of partial nephrectomy (PN) vs radical nephrectomy (RN).

Patients and methods: Between January 2004 and June 2008, 203 patients were treated for clinical T1a renal cortical tumours. Of these, 154 (75.8%) had all data available and form the analytic cohort. Patients were categorized into two groups, PN and RN, based on preoperative treatment plan. Patient-, procedure-, and tumour-related variables, together with tumour complexity (based on the R.E.N.A.L Nephrometry Score [RENAL-NS]) were evaluated for their association with planned PN vs RN.

Results: PN was planned in 120/154 patients (77.9%). Minimally invasive surgical approaches were planned in 66/154 cases overall (42.9%) and in 40/120 PN cases (33.3%). On univariate analysis, lower American Society of Anesthesiologists (ASA) score, planned open approach, smaller tumour size, left-sided tumour, and lower RENAL-NS were associated with planned PN. On multivariate analysis three factors remained independently associated with PN: tumour size (each 1 cm decrease in tumour size odds ratio [OR] 2.2, 95% confidence interval [CI] 1.2-4.0, P= 0.011), tumour complexity quantified by RENAL-NS (each 1 point decrease OR 2.4, 95% CI 1.5-3.7, P < 0.001), and planned open surgical approach (OR 7.3, 95% CI 2.2-25, P= 0.001).

Conclusions: The decision to perform elective PN is based primarily on tumour anatomical features but is also associated with surgical approach. The RENAL-NS accurately predicts nephrectomy type in clinical T1a renal cortical tumours.