Kidney function outcomes following thermal ablation of small renal masses

Ablation of Kidney Tumors in Patients with Substantial Kidney Impairment: Current Status

PURPOSE OF REVIEW

To review the current status of kidney tumor ablation in patients with substantial kidney impairment.

RECENT FINDINGS

Few reports of kidney tumor ablation in such patients have recently been published. The reported prevalence of patients with stage 4 or 5 chronic kidney disease (CKD) among patients undergoing ablation is 2.0%-10%. In patients with stage 4 or 5 CKD, local tumor control rates were 88%-100%. The effect of ablation on CKD stage is unclear, and the observed deteriorations in kidney function are consistent with both the effect of cryoablation and the natural course of advanced CKD. According to guidelines, active surveillance may be selected. The goals of treatment are complete tumor removal and maintenance of kidney function, both of which can be met by ablation. Given the limited treatment options, ablation may play a pivotal role in the management of patients with advanced CKD.

Effect of iodinated contrast material on post-operative eGFR when administered during renal mass ablation

OBJECTIVE

To evaluate the effect of intravenous iodinated contrast on estimated glomerular filtration rate (eGFR) when administered immediately after thermal ablation of clinically localized T1a (cT1a) renal cell carcinoma (RCC).

METHODS

This HIPAA-compliant, dual-center retrospective study was performed under a waiver of informed consent. Three hundred forty-two consecutive patients with cT1a biopsy-proven RCC were treated with percutaneous ablation between January 2010 and December 2017. Immediate post-ablation contrast-enhanced CT was the routine standard of care at one institution (contrast group), but not the other (control group). One-month pre- and 6-month post-ablation eGFR were compared using the Wilcoxon signed-rank test or the Kruskal-Wallis test. Multivariate linear regression was used to determine the effect of contrast on eGFR. A 1:1 propensity score matching was performed for all patients with a logistic model using patient, tumor, and procedural covariates.

RESULTS

In total, 246 patients (158 M; median age 69 years, IQR 62-74) were included. Median tumor diameter (2.4 vs 2.5, p = 0.23) and RENAL nephrometry scores (6 vs 6, p = 0.92), surrogates for ablation zone size, were similar. Baseline kidney function was similar for the control and contrast groups, respectively (median eGFR: 70 vs 74 mL/min/1.73 m², p = 0.29). There was an expected mild decline in eGFR after ablation (control: 70 vs 60 mL/min/1.73 m², p < 0.001; contrast: 75 vs 71 mL/min/1.73 m², p = 0.001). Intravenous iodinated contrast was not associated with a decline in eGFR on multivariate linear regression (1.91, 95% CI - 3.43-7.24, p = 0.46) or 1:1 propensity score-matched model (- 0.33, 95% CI - 6.81-6.15, p = 0.92).

CONCLUSION

Intravenous iodinated contrast administered during ablation of cT1a RCC has no effect on eGFR.

KEY POINTS

• Intravenous iodinated contrast administered during thermal ablation of clinically localized T1a renal cell carcinoma has no effect on kidney function. • Thermal ablation of clinically localized T1a renal cell carcinoma results in a mild decline in kidney function. • A decline in kidney function is similar for radiofrequency and microwave ablation of clinically localized T1a renal cell carcinoma.

Renal cryoablation - a practical guide for interventional radiologists

Renal cryoablation is a treatment option for early stage renal cell carcinomas with excellent oncological outcomes and low morbidity. This review outlines the technique of renal cryoablation and provides a guide for interventional radiologists on setting up an integrated service within a renal cancer network multidisciplinary setting. Patient selection and preparation, together with the technical aspects which ensure optimal oncological outcomes and avoid collateral damage to adjacent organs are highlighted.

Usefulness of a Pretreatment CT-Based Modified RENAL Nephrometry Score in Predicting Renal Function After Cryotherapy for T1a Renal Mass

PURPOSE

We investigated the usefulness of the modified RENAL nephrometry (mRN) scoring system for predicting post-cryotherapy renal function in patients with T1a renal mass.

PATIENTS AND METHODS

A total of 75 patients with a T1a renal mass were enrolled. The mRN score was determined based on the tumor size, the tumor's exophytic/endophytic properties, the tumor's nearness to the collecting system, and the anterior/posterior location of the kidney. The change in the estimated glomerular filtration rate (ΔeGFR) was calculated as follows: ΔeGFR = 100 × ([pretreatment eGFR - eGFR at 6 months after cryotherapy]/pretreatment eGFR). Based on the ΔeGFR results, we classified the patients into two groups: a preserved renal function group (ΔeGFR < 10%) and an impaired renal function group (ΔeGFR ≥ 10%). We then analyzed the relationships between the mRN score and ΔeGFR and between the mRN score and the chronic kidney disease (CKD) stage.

RESULTS

The mean ΔeGFR for all patients was 5.5%. The mRN scores of the preserved renal function group (5.8 ± 0.3) were significantly lower than those of the impaired group (7.4 ± 0.3) (p < 0.001). When the mRN score cutoff value was set at 7 points, the mRN had 67.7% sensitivity, 72.7% specificity, 61.8% positive predictive value (PPV), 76.1% negative predictive value (NPV), and 70.7% accuracy for predicting impaired renal function. For predicting a deterioration of CKD stage, the mRN had 92.9% sensitivity, 67.2% specificity, 39.4% PPV, 97.6% NPV, and 72% accuracy.

CONCLUSION

Our newly proposed modified RENAL nephrometry score was suggested to be useful for predicting renal function after renal cryotherapy.

Risk Assessment of Chronic Kidney Disease following Microwave Ablation for Stage T1 Renal Cell Carcinoma

PURPOSE

To assess safety and renal-function outcomes after microwave (MW) ablation of localized stage T1 renal cell carcinoma (RCC).

MATERIALS AND METHODS

A retrospective review was conducted of 38 patients (28 men; mean age, 69 y; range, 51-88 y) who underwent computed tomography (CT)-guided MW ablation for stage T1N0M0 RCC. Baseline and follow-up renal function surrogates including creatinine level and estimated glomerular filtration rate (eGFR) were statistically compared. Peri- and postoperative complication rates, technical success, and treatment response were also assessed.

RESULTS

A total of 44 biopsy-proven stage T1N0M0 RCCs measuring 1.2-6.9 cm (mean, 2.5 cm) were treated, and renal function was measured 1 mo after treatment. Mean eGFRs were 60 mL/min/1.73 m² at baseline and 59 mL/min/1.73 m² at 1 month after ablation. At 1-year and last follow-ups, the means of difference were 3.3% (95% confidence interval, -4.4 to 4.3; P = .99) and 3.3% (95% confidence interval, -4.3 to 4.8; P = .91), respectively. The 2-years freedom from eGFR decrease to < 60 mL/min/1.73 m² was 2% (P = .91). Among the 5 patients (13%) with preexisting stage 4 chronic kidney disease (CKD; eGFR < 30 mL/min/1.73 m²) before ablation, there was no significant postablative onset of decline or CKD upstaging (P = .001). There were no major complications, and 5 patients (13%) had small asymptomatic perinephric hematomas (Society of Interventional Radiology minor complication, class A/B) that were managed conservatively.

CONCLUSIONS

At 2-year follow-up, CT-guided percutaneous MW ablation is safe and well-tolerated and achieves nephron preservation similar to existing ablative modalities.

Trends in the Authorship of Peer Reviewed Publications in the Urology Literature

INTRODUCTION

We evaluated the authorship count of all original research and review articles published in prominent Urology journals to trend patterns in authorship over the last decade. Secondarily, we evaluated bibliometric assessments and sought to understand whether authorship count was associated with citation rate and each article's field-normalized measure of impact.

METHODS

Information on authorship count, date of publication, study type, journal of publication, citation rate, and relative citation ratio (RCR) was collected for all original research and review articles published in European Urology, Journal of Urology, Urology, and British Journal of Urology International between 2006 and 2016. We examined trends in authorship count over the past decade, as well as between journals and article types.

RESULTS

21,336 articles were analyzed, of which 19,527 (91.5%) were original research and 1,809 (8.5%) were review articles. Overall, number of authors increased 46.1% from 2006 to 2016. Authorship counts in original research articles increased by an average of 2.45 per manuscript (43.3% increase) over the decade analyzed. More dramatically, authorship counts in review articles increased by an average of 3.14 per manuscript (92.6% increase). Articles with higher authorship counts were associated with more citations and greater RCR (r=0.13, p<0.001).

CONCLUSION

There is a global trend towards more authors per article in urology publications-in both original research publications and review articles, and across each of the individual journals evaluated. An increase in author count has also been associated with increased citations and measures of article impact.