Management of Small Renal Masses

Perioperative, functional, and oncologic outcomes after ablation or partial nephrectomy for solitary renal tumors: a systematic review and meta-analysis of comparative trials

Objectives

The perioperative, functional, and oncological outcomes of patients with solitary small renal tumors (SRMs) treated with ablation (AT) or partial nephrectomy (PN) remain controversial. The aim of this study was to compare the outcomes of these two surgical techniques.

Methods

In April 2023, we conducted a literature search in several widely used databases worldwide, including PubMed, Embase, and Google Scholar. Review Manager was used to compare various parameters. The study was registered with PROSPERO (CRD42022377157).

Results

Our final meta-analysis included 13 cohort studies with a total of 2,107 patients. Compared to partial nephrectomy (PN), ablation (AT) had shorter hospital stays (WMD -2.37 days, 95% CI -3.05 to -1.69; p < 0.00001), shorter operating times (WMD -57.06 min, 95% CI -88.92 to -25.19; p = 0.0004), less postoperative creatinine increases (WMD -0.17 mg/dL, 95% CI -0.29 to -0.05; p = 0.006), less postoperative glomerular filtration rate decreases (WMD -9.84 mL/min/1.73 m2, 95% CI -14.25 to -5.44; p < 0.0001), less postoperative new-onset chronic kidney disease (OR 0.33, 95% CI 0.16 to 0.71; p = 0.005), and less intraoperative blood loss (WMD -285.92 ml, 95% CI -428.44 to -143.40; p < 0.0001). The transfusion rate was lower in the ablation group (OR 0.17, 95% CI 0.06 to 0.51; p = 0.001). The risk of local recurrence was higher in the ablation group (OR 2.96, 95% CI 1.27 to 6.89; p = 0.01), while the risk of distant metastasis was higher in the partial nephrectomy group (OR 2.81, 95% CI 1.28 to 6.18; p = 0.01). The intraoperative and postoperative complication rates were lower in the ablation group (OR 0.23, 95% CI 0.08 to 0.62; p = 0.004 and OR 0.21, 95% CI 0.11 to 0.38; p < 0.00001, respectively). However, overall survival, postoperative dialysis rate, and tumor-specific survival were not different between the two groups.

Conclusions

Our data suggest that ablation and partial nephrectomy are equally safe and effective in the treatment of small solitary kidney tumors and are better options for patients with poor preoperative physical condition or poor renal function.

Staging, surveillance, and evaluation of response to therapy in renal cell carcinoma: role of MDCT

Renal cell carcinoma is the most common malignant renal tumor in the adults. Significant advances have been made in the management of localized and advanced renal cell carcinoma. Surgery is the standard of care and accurate pre-operative staging based on imaging is critical in guiding appropriate patient management. Besides staging, imaging plays a key role in the post-operative surveillance and evaluation of response to systemic therapies. Both CT and MR are useful in the staging and follow up of renal cell carcinoma, but CT is more commonly used due to its lower costs and wider availability. In this article, we discuss and illustrate the role of multi-detector CT in pre-operative staging, post-operative surveillance, and evaluation of response to systemic therapy in renal cell carcinoma.

Textural differences in apparent diffusion coefficient between low- and high-stage clear cell renal cell carcinoma

OBJECTIVE

The purpose of this article is to evaluate differences in texture measures on apparent diffusion coefficient (ADC) maps between low- and high-stage clear cell renal cell carcinomas (RCCs).

MATERIALS AND METHODS

In this retrospective study, 61 patients with clear cell RCC at pathologic examination and who underwent preoperative MRI with diffusion-weighted imaging were included. Clear cell RCCs were clinically staged on review of preoperative MRI by a board-certified radiologist blinded to the pathologic findings. Whole lesions were segmented on ADC maps by two readers independently, from which first-order texture features (i.e., mean and skewness) and second-order texture features (i.e., cooccurrence matrix measures) were calculated. Texture metrics were compared between low- and high-stage clear cell RCC.

RESULTS

In 61 patients, there were 62 clear cell RCCs (33 low stage [stages I and II] and 29 high stage [stages III and IV]) at pathologic examination. Staging accuracy of qualitative interpretation was 100% for low-stage lesions and 37.9% (11/29) for high-stage lesions. There was no statistically significant difference in mean ADC between high- and low-stage clear cell RCCs (1.77×10(-3) vs 1.80×10(-3) mm2/s; p=0.7). However, high-stage clear cell RCCs were larger (6.96±2.93 vs 3.49±1.57 cm; p<0.0001) and had statistically significantly (p≤0.0001) higher ADC skewness (0.02±0.33 vs -0.52±0.65) and cooccurrence matrix correlation (0.64±0.11 vs 0.49±0.13). Multivariate logistic regression identified size, skewness, and cooccurrence matrix correlation as significant independent predictors of high stage (AUC=0.92). Interreader correlation in texture metrics ranged from 0.82 to 0.89.

CONCLUSION

First- and second-order ADC texture metrics differ between low- and high-stage clear cell RCCs. A model that includes size and ADC texture measures may help to stage clear cell RCCs noninvasively.

Comparison of utility of tumor size and apparent diffusion coefficient for differentiation of low- and high-grade clear-cell renal cell carcinoma

BACKGROUND

There is a significant correlation between tumor size and tumor grade for clear-cell renal cell carcinoma (RCC) in pathology. Thus, apparent diffusion coefficient (ADC) of clear-cell RCC might be influenced by tumor size.

PURPOSE

To compare the utility of tumor size and ADC for distinguishing low-grade from high-grade clear-cell RCC.

MATERIAL AND METHODS

Forty-nine patients undergoing preoperative magnetic resonance imaging were retrospectively assessed. ADC values were calculated using b-value combinations of 0 and 800 s/mm(2) at 1.5 T. Two radiologists in consensus measured ADC values via small region of interest (ROI) (mean ROI area, 88.8 mm(2); range, 80-108 mm(2)) placement on an area of solid tumor on a single slice. Maximum tumor diameter was measured at the maximum tumor area. A single pathologist reviewed all pathological slides to determine the nuclear grade according to the Fuhrman classification. The utility of ADC, tumor size, and ADC/size ratio for distinguishing low-grade from high-grade tumors was assessed. Receiver-operating characteristic (ROC) analysis and regression analysis of the each index were performed. The correlation between ADC and tumor size was also investigated.

RESULTS

The 49 clear-cell RCC included 34 low-grade and 15 high-grade tumors. The differences of ADC, tumor size, and ADC/size ratio between high-grade and low-grade tumors were statistically significant (P <0.05). The area under the ROC curve of ADC, tumor size, and ADC/size ratio were 0.802, 0.763, and 0.804 respectively. However, using regression analysis, only ADC (P <0.05) was statistically significant index as independent risk factors for high-grade clear-cell RCC. Moreover, weak significant correlation was observed between tumor size and ADC (R(2) = 0.3865, P <0.01).

CONCLUSION

There was a weak significant correlation between tumor size and ADC value of clear-cell RCC. Using ROC and regression analysis, ADC was statistically significant index for distinguishing low-grade from high-grade clear-cell RCC more than tumor size and ADC/size ratio.

Renal function outcomes in patients treated with partial nephrectomy versus percutaneous ablation for renal tumors in a solitary kidney

PURPOSE

Partial nephrectomy is the recommended management for small renal masses. Percutaneous ablation is safe and effective with comparable short-term cancer specific survival. Currently to our knowledge data are lacking on the impact of thermal ablation on renal function preservation. We examined the impact on renal function of partial nephrectomy vs percutaneous ablation in patients with a solitary kidney.

MATERIALS AND METHODS

We performed a retrospective review to identify patients with a solitary kidney who underwent partial nephrectomy or percutaneous ablation at Mayo Clinic Rochester between 2003 and 2009. Preoperative characteristics and 3-month posttreatment renal function were compared using the Wilcoxon rank sum, chi-square and Fisher exact tests.

RESULTS

During the study period 50 patients underwent percutaneous ablation and 62 underwent partial nephrectomy. At partial nephrectomy no ischemia was used in 30 cases (48%), a median of 28 minutes of cold ischemia was used in 26 (42%) and a median of 18 minutes of warm ischemia was used in 6 (10%). Patients who underwent partial nephrectomy were younger (median age 62.5 vs 68.5 years, p = 0.01) and harbored larger tumors (median 3.5 vs 2.5 cm, p = 0.005) with higher nephrometry scores (median 9 vs 7, p = 0.03). At 3-month posttreatment followup no differences were noted between the 2 groups in glomerular filtration rate (p = 0.91), change in glomerular filtration rate (p = 0.77) or change in chronic kidney disease stage (p = 0.87). Similar results were observed when adjusting for age, tumor size and nephrometry score on multivariate analysis.

CONCLUSIONS

With judicious use of ischemia partial nephrectomy, even for more complex tumors, has short-term renal function outcomes similar to those of percutaneous ablation.

The changing face of renal-cell carcinoma

The present decade can be credited with the improved understanding of renal-cell carcinoma (RCC), its local and systemic management, and various controversies from diagnosis to types of various available interventions. The old paradigms and dogmas are no longer accepted as "the best way" without evidence, and many "old" principles are cautiously questioned. These notions have resulted in new knowledge, questions, arguments, and treatment options. This article will describe the "changing face of RCC" over the past several years and will briefly summarize the major changes and issues in the field of renal oncology. The discussed topics include improved molecular understanding of RCC, management of small renal masses, the safety and accuracy of renal mass biopsy, the emerging role of molecular imaging, the importance of maximal renal preservation, and the evolving role of laparoscopy, robotics, and ablation.