Login to Access Video or Poster Abstract: MP100-17
Sources of Funding: none

Introduction

The optimal approach for a renal tumor in a solitary kidney is unknown. Our objective was to compare outcomes between partial nephrectomy (PN) and percutaneous cryoablation (PCA) for tumors in a solitary kidney.

Methods

Patients with a solitary kidney undergoing PN or PCA for a single localized primary renal tumor between 2005-2015 were identified using Mayo Clinic Registries. Exclusions were inherited tumor syndromes, multiple tumors, and salvage procedures. To achieve balance in baseline characteristics, inverse probability of treatment weighting (IPTW) was employed using propensity scores computed based on age, Charlson co-morbidity index, treatment year, nephrometry score, tumor size, baseline estimated glomerular filtration rate (eGFR), confirmed renal cell carcinoma (RCC) histology, and history of prior contralateral nephrectomy for RCC. Complications (Clavien scale), renal function outcomes, local recurrence, distant metastasis, and cancer-specific survival were compared between groups using logistic, linear, and Fine-and-Gray competing risks regression modeling.

Results

The cohort included 118 patients (PN: 64; PCA: 54) with a median follow-up of 48 months (IQR 23,80). In unadjusted analyses, PCA was associated with a decreased risk of complications (15% vs 31%; OR=0.4; 95%CI 0.2-1.0; p=0.04). However, upon accounting for baseline differences with IPTW-adjustment, there was no longer a significant difference in risk of complications (26% vs 27%; OR=1.0; 95%CI 0.4-2.2; p=0.9). Higher nephrometry score was associated with greater risk of complications for both PN (OR[per 1 point]=1.5; 95%CI 1.1-2.0; p=0.01) and PCA (OR[per 1 point]=1.7; 95%CI 1.0-2.9; p=0.04), but nephrometry score did not modify the effect of treatment modality on the risk of complications (p-interaction=0.17).Median percentage drop in eGFR from baseline to 3 months from treatment was 16% and 7% for PCA and PN, respectively (p=0.23). There were no significant differences between PCA and PN in risk of local recurrence (HR=1.0; 95%CI 0.3-3.4; p>0.9), distant metastasis (HR=0.7; 95%CI 0.2-1.9; p=0.5), or cancer-specific mortality (HR=1.4; 95%CI 0.2-8.0; p=0.7).

Conclusions

Both PN and PCA appear to be viable options for renal tumors in solitary kidneys. Although PCA was associated with fewer complications in unadjusted analyses, there were no significant differences between PCA and PN, regardless of tumor complexity, when adjusting for treatment selection bias. Short term oncologic outcomes appear similar although additional follow-up is needed.

Funding

none