The Role of Minimally Invasive Surgery in Multifocal Renal Cell Carcinoma

Trifecta Outcomes in Multifocal Tumors: A Comparison Between Robotic and Open Partial Nephrectomy

OBJECTIVES

To report a comparative analysis of outcomes in patients who underwent multiple excisions for unilateral synchronous multifocal renal tumors using both open and robotic approaches.

METHODS

We retrospectively reviewed 110 patients who underwent robotic and open partial nephrectomy and had multiple tumor excisions in an ipsilateral kidney. "Trifecta" was defined as negative surgical margins, no urologic complications, and a glomerular filtration rate (GFR) preservation of ≥90% at last follow-up. Inverse probability of treatment weighting (IPTW) was applied to equilibrate treatment groups, minimize selection bias, and optimize inference on the basis of each patient's clinicodemographic characteristics.

RESULTS

Sixty-eight robotic and 42 open patient approaches had sufficient data for IPTW. After weighting, there were no statistical differences in baseline characteristics between the two groups. On adjusted analyses, robotic partial nephrectomy achieved equivalent rates of trifecta to open surgery (16.3% vs 16.5%, p = 0.99), which persisted on subgroup analyses of patients with two (20.1% vs 23.7%, p = 0.82) or more than two tumors (6.8% vs 7.4%, p = 0.95). There were no differences between robotic and open cohorts for negative margin rates, absence of complications, or GFR ≥90%. The robotic cohort had a shorter mean length of stay (3.4 vs 4.9 days, p < 0.001).

CONCLUSIONS

Surgical resection remains the mainstay for patients with unilateral, synchronous, and multifocal renal tumors. Our analysis found that both open and robotic approaches to partial nephrectomy are equally likely to achieve the "trifecta" outcome in an equilibrated high-risk group of patients. The robotic approach for these complex patients may be safe and feasible for a carefully selected group of patients.

In vivo irreversible electroporation kidney ablation: experimentally correlated numerical models

Irreversible electroporation (IRE) ablation uses brief electric pulses to kill a volume of tissue without damaging the structures contraindicated for surgical resection or thermal ablation, including blood vessels and ureters. IRE offers a targeted nephron-sparing approach for treating kidney tumors, but the relevant organ-specific electrical properties and cellular susceptibility to IRE electric pulses remain to be characterized. Here, a pulse protocol of 100 electric pulses, each 100 μs long, is delivered at 1 pulse/s to canine kidneys at three different voltage-to-distance ratios while measuring intrapulse current, completed 6 h before humane euthanasia. Numerical models were correlated with lesions and electrical measurements to determine electrical conductivity behavior and lethal electric field threshold. Three methods for modeling tissue response to the pulses were investigated (static, linear dynamic, and asymmetrical sigmoid dynamic), where the asymmetrical sigmoid dynamic conductivity function most accurately and precisely matched lesion dimensions, with a lethal electric field threshold of 575 ± 67 V/cm for the protocols used. The linear dynamic model also attains accurate predictions with a simpler function. These findings can aid renal IRE treatment planning under varying electrode geometries and pulse strengths. Histology showed a wholly necrotic core lesion at the highest electric fields, surrounded by a transitional perimeter of differential tissue viability dependent on renal structure.

Pathological concordance and surgical outcomes of sporadic synchronous unilateral multifocal renal masses treated with partial nephrectomy

PURPOSE

Patients with unilateral synchronous multifocal renal masses represent a unique population with renal cell carcinoma. While pathological concordance rates have been studied for bilateral cases, limited data exist on unilateral multifocal disease. We characterized pathological concordance rates in this population and evaluated the outcomes of nephron preservation.

MATERIALS AND METHODS

Patients who underwent surgery from 2000 to 2012 for unilateral synchronous multifocal renal masses were identified from a prospectively maintained database. Demographic, surgical and pathological outcomes of this cohort were analyzed. Malignant concordance rates were defined as agreement of all malignant tumor types in a single renal unit. Histological concordance was defined as agreement of all resected mass histologies, eg all clear cell carcinomas. Nuclear grade was considered concordant if all tumors excised were low (Fuhrman 1 or 2, type 1) or high (Fuhrman 3 or 4, type 2) grade.

RESULTS

Using our institutional database of 2,569 patients with renal tumors we identified 97 with unilateral synchronous multifocal renal masses. Malignant and benign concordance rates were 77.2% and 48.6%, and histological and grade concordance rates were 58.8% and 51.5%, respectively. In this cohort we identified 76 patients (76.3% male) with a median age of 62.5 years who had a total of 241 unilateral synchronous multifocal renal masses and underwent nephron sparing surgery. Median mass size was 2.0 cm (IQR 1.1-3.1), there was a median of 3 tumors per patient and median followup was 24 months (IQR 13-40). Identified renal cell carcinoma histologies included clear cell in 49.4% of cases, papillary in 33.5%, mixed in 4.5% and chromophobe in 2.8%.

CONCLUSIONS

In what is to our knowledge the largest published report of unilateral synchronous multifocal renal masses we document low pathological concordance rates. As such, percutaneous biopsy of a single renal mass in these patients may not help inform treatment decisions. Nephron sparing surgery may be performed with acceptable oncological and functional results in patients with unilateral synchronous multifocal renal masses.