Comprehensive Management of Renal Masses in Solitary Kidneys

Abstract

Background: A renal mass in a solitary kidney (RMSK) has traditionally been managed with partial nephrectomy (PN), although radical nephrectomy (RN) is occasionally required. Most RMSK studies have focused on patients for whom PN was achieved.

Objective: To provide a comprehensive analysis of the management strategies/outcomes for an RMSK and address knowledge deficits regarding this challenging disorder.

Design, setting, and participants: A total of 1024 patients diagnosed with an RMSK (1975-2022) were retrospectively evaluated. Baseline characteristics and pathologic/functional/survival outcomes were analyzed.

Intervention: PN/RN/cryoablation (CA)/active surveillance (AS).

Outcome measurements and statistical analysis: Functional outcomes, perioperative morbidity/mortality, and 5-yr recurrence-free survival (RFS) were evaluated. Kruskal-Wallis and chi-square tests were used to compare cohorts, and log-rank test and Cox proportional hazard model were used for survival analysis.

Results and limitations: Of 1024 patients, 842 underwent PN (82%), 102 CA (10%), 54 RN (5%), and 26 AS (3%). The median tumor size and RENAL([R]adius [tumor size as maximal diameter], [E]xophytic/endophytic properties of tumor, [N]earness of tumor deepest portion to collecting system or sinus, [A]nterior [a]/posterior [p] descriptor, and [L]ocation relative to polar lines) score were 3.7 cm and 8, respectively. The median follow-up was 53 mo. For PN, 95% were clamped, and the median warm and cold ischemia times were 22 and 45 min, respectively. For PN, the median preoperative glomerular filtration rate (GFR) was 57 ml/min/1.73 m², and the median new baseline and 5-yr GFRs were 47 and 48 ml/min/1.73 m², respectively. Dialysis-free survival for PN was 97% at 5 yr. Twenty-two (2.1%) patients with clear-cell renal cell carcinoma and RENAL score ≥10 (median = 11) received tyrosine kinase inhibitors (TKIs) to facilitate PN, leading to 57% median decrease of tumor volume; PN was accomplished in 20 (91%). Forty-one patients had planned RN (4.0%), most often due to severe pre-existing chronic kidney disease (CKD), and 13 were converted from PN to RN (1.5%). Clavien III-V perioperative complications were observed in 80 (8%) patients and 90-d mortality was 0.6%. Five-year RFS for PN, CA, and RN were 83%, 80%, and 72%, respectively (p = 0.03 for PN vs RN).

Conclusions: Nephron-sparing approaches are feasible and successful in most RMSK patients. PN for an RMSK is often challenging but can be facilitated by selective use of TKIs. RN is occasionally required due to severe CKD, over-riding oncologic concerns, or conversion from PN. This is the first large RMSK study to provide a comprehensive analysis of all management strategies/outcomes.

Patient summary: Kidney cancer in a solitary kidney is a major challenge for achieving cancer-free status and avoiding dialysis. Although partial nephrectomy is the principal treatment for a renal mass in a solitary kidney, other options are occasionally required to optimize outcomes.

Keywords: Active surveillance; Cryoablation; Partial nephrectomy; Radical nephrectomy; Renal mass; Solitary kidney.