Renal mass biopsy and thermal ablation: should biopsy be performed before or during the ablation procedure?

Cost-Effectiveness Analysis Comparing Biopsy in Advance of Ablation with Concurrent Biopsy and Ablation for Small Renal Masses Measuring 1-3 cm

PURPOSE

To analyze the cost effectiveness of performing a renal mass biopsy in advance of ablation or concurrently with a percutaneous ablation procedure for the management of small renal masses (SRMs).

MATERIALS AND METHODS

A decision-analytic model was developed with a cohort of 65-year-old male patients with an incidental, unilateral 1-3 cm SRM. A decision tree modeled the first year of clinical intervention, after which patients entered a Markov model with a lifetime horizon. Patients were assumed to be treated in accordance with established clinical practice guidelines, including surveillance, repeat ablation for recurrence, and systemic therapy for metastasis. Healthcare cost and utility values were determined from published literature or local hospital estimates, discounted at 1.5%. Total lifetime costs were calculated from the perspective of a Canadian healthcare payer and converted to 2022 Canadian dollars (C$). The primary outcome was incremental cost-effectiveness ratio (ICER) at a willingness-to-pay threshold of C$50,000 per quality-adjusted life year (QALY) gained. The secondary outcome was ICER at a willingness-to-pay threshold of C$50,000 per life year (LY) gained.

RESULTS

Concurrent biopsy and ablation resulted in a gain of 16.4 quality-adjusted days, at an incremental cost of $386, with an ICER of C$8,494/QALY. The concurrent strategy was the dominant strategy for a prevalence of benign mass of <5%. Sequential biopsy and ablation was only cost-effective when LYs were not quality-adjusted and ablation cost was >C$4,300 or benign mass prevalence was >28%.

CONCLUSIONS

Concurrent biopsy and ablation is cost-effective relative to pretreatment diagnostic biopsy for management of incidental SRMs.

Renal mass biopsy - a practical and clinicopathologically relevant approach to diagnosis

Advancements in imaging modalities have increased the frequency of renal mass discovery. Imaging has typically been considered sufficient to guide management for a large proportion of these tumours, but renal mass biopsies (RMBs) have an increasing role in determining malignancy and can be a valuable tool for preventing unnecessary surgery in patients with benign tumours. A structured approach should be used to help to navigate the expanding repertoire of renal tumours, many of which are molecularly defined. In terms of tumour subtyping, the pathologist's strategy should focus on stratifying patients into clinically different prognostic groups according to our current knowledge of tumour behaviour, including benign, low-grade or indolent, intermediate malignant or highly aggressive. Crucial pathological features and morphological mimicry of tumours can alter the tumour's prognostic group. Thus, pathologists and urologists can use RMB to select patients with tumours at a reduced risk of progression, which can be safely managed with active surveillance within a tailored imaging schedule, versus tumours for which ablation or surgical intervention is indicated. RMB is also crucial in the oncological setting to distinguish between different high-grade tumours and guide tailored management strategies.

Percutaneous radiofrequency ablation is an effective treatment option for small renal masses, comparable to partial nephrectomy

OBJECTIVES

The standard therapy for small renal masses (SRMs) remains partial nephrectomy (PN), which is associated with relatively high morbidity and complication rate. Therefore, percutaneous radiofrequency ablation (PRFA) emerges as an alternative therapy. This study aimed to compare the efficacy, safety, and oncological outcomes of PRFA versus PN.

METHODS

A multicenter non-inferiority study with retrospective analysis of 291 patients with SRMs (N0M0), who underwent PN or PRFA (2:1), recruited prospectively from two hospitals in the Andalusian Public Health System, Spain, between 2014 and 2021. Comparisons of treatment features were evaluated using the t test, Wilcoxon-Mann-Whitney U test, chi-square test, Fisher test, and Cochran-Armitage trend test. Kaplan-Meier curves depicted overall survival (OS), local recurrence-free survival (LRFS), and metastasis-free survival (MFS) rates in the overall study population.

RESULTS

A total of 291 consecutive patients were identified; 111 and 180 patients underwent PRFA and PN, respectively. Median follow-up time was 38 and 48 months, and mean hospitalization days were 1.04 and 3.57 days, respectively. The variables underpinned with high surgical risk were significantly increased in PRFA compared to those in PN (mean age was 64.56 and 57.47 years, the solitary kidney presence was 12.6% and 5.6%, ASA score ≥ 3 was 36% and 14.5%, respectively). The rest of oncological outcomes were comparable amongst PRFA and PN. Patients undergoing PRFA did not improve OS, LRFS, and MFS compared to those undergoing PN. Limitations comprise retrospective design and limited statistical power.

CONCLUSION

PRFA for SMRs in high-risk patients is non-inferior in terms of oncological outcomes and safety compared to PN.

CLINICAL RELEVANCE STATEMENT

Our study has a direct clinical application as it proves that radiofrequency ablation is an effective and uncomplicated therapeutic option for patients with small renal masses.

KEY POINTS

•There are non-inferiority results in overall survival, local recurrence-free survival, and metastasis-free survival between PRFA and PN. •Our two-center study showed that PRFA is non-inferior to PN in oncological outcomes. •Contrast-enhanced power ultrasound-guided PRFA provides an effective therapy for T1 renal tumors.

Contrast-enhanced CT immediately following percutaneous microwave ablation of cT1a renal cell carcinoma: Optimizing cancer outcomes

OBJECTIVE

To evaluate the effect of intra-procedural contrast-enhanced CT (CECT) and same-session repeat ablation (SSRA) on primary efficacy, the complete eradication of tumor after the first ablation session as confirmed on first imaging follow-up, of clinically localized T1a (cT1a) renal cell carcinoma (RCC).

METHODS

398 consecutive patients with cT1a RCC were treated with cryoablation between 10/2003 and 12/2017, radiofrequency (RFA) or microwave ablation (MWA) between 1/2010 and 12/2017. SSRA was performed for residual tumor identified on intra-procedural CECT. Kruskal-Wallis and Pearson's chi-squared tests were performed to assess differences in continuous and categorical variables, respectively. Multivariate linear regression was used to determine predictors for primary efficacy and decline in estimated glomerular filtration rate.

RESULTS

347 consecutive patients (231 M, mean age 67.5 ± 9.1 years) were included. Median tumor diameter was smaller [2.5 vs 2.7 vs 2.6 (p = 0.03)] and RENAL Nephrometry Score (NS) was lower [6 vs 7 vs 7 (p = 0.009] for MWA compared to the RFA and cryoablation cohorts, respectively. Primary efficacy was higher in the MWA cohort [99.4% (170/171)] compared to the RFA [91.4% (85/93)] and cryoablation [92.8% (77/83)] cohorts (p = 0.001). Microwave ablation and SSRA was associated with higher primary efficacy on multivariate linear regression (p = 0.01-0.03).

CONCLUSION

MWA augmented by SSRA, when residual tumor is identified on intra-procedural CECT, may improve primary efficacy for cT1a RCC.

Split-bolus CT urography after microwave ablation of renal cell carcinoma improves image quality and reduces radiation exposure

OBJECTIVE

To compare image quality and radiation dose between single-bolus 2-phase and split-bolus 1-phase CT Urography (CTU) performed immediately after microwave ablation (MWA) of clinically localized T1 (cT1) RCC.

METHODS

Forty-two consecutive patients (30 M, mean age 67.5 ± 9.0) with cT1 RCC were treated with MWA from 7/2013 to 12/2013 at two academic quaternary-care institutions. Renal parenchymal enhancement, collecting system opacification and distention and size-specific dose estimate (SSDE) were quantified and image quality subjectively assessed on single-bolus 2-phase versus split-bolus 1-phase CTU. Kruskal-Wallis and Pearson's Chi-squared tests were performed to assess differences in continuous and categorical variables, respectively. Two-sample T test with equal variances was used to determine differences in quantitative and qualitative image data.

RESULTS

Median tumor diameter was larger [2.9 cm (IQR 1.7-5.3) vs 3.6 cm (IQR 1.7-5.7), p = 0.01] in the split-bolus cohort. Mean abdominal girth (p = 0.20) was similar. Number of antennas used and unenhanced CTs obtained before and during MWA were similar (p = 0.11-0.32). Renal pelvis opacification (2.5 vs 3.5, p < 0.001) and distention (4 mm vs 8 mm, p < 0.001) were improved and renal enhancement (Right: 127 HU vs 177 HU, p = 0.001; Left: 124 HU vs 185 HU, p < 0.001) was higher for the split-bolus CTU. Image quality was superior for split-bolus CTU (3.2 vs 4.0, p = 0.004). Mean SSDE for the split-bolus CTU was significantly lower [163.9 mGy (SD ± 73.9) vs 36.3 mGy (SD ± 7.7), p < 0.001].

CONCLUSION

Split-bolus CTU immediately after MWA of cT1 RCC offers higher image quality, improved opacification/distention of the collecting system and renal parenchymal enhancement at a lower radiation dose.

Renal Mass Biopsy

Kidney cancer accounts for 2% of cancer related deaths. Historically, a patient with a solid renal mass would undergo surgery without biopsy given the previously low diagnostic yield of biopsy and the fear of tumor seeding. This led to a high rate of resection for benign masses. With the rising incidence of renal masses discovered on imaging, improvements in biopsy technique and advancements in pathologic evaluation of biopsy samples of renal masses, renal mass biopsy now plays an important role in selected patients with renal masses. Coaxial core needle biopsy is the preferred technique with a low rate of complications and a high diagnostic yield. This article will discuss indications, methods, utility, limitations and complications of renal mass biopsy.

Imaging considerations for thermal and radiotherapy ablation of primary and metastatic renal cell carcinoma

Ablative (percutaneous and stereotactic) thermal and radiotherapy procedures for management of both primary and metastatic renal cell carcinoma are increasing in popularity in clinical practice. Data suggest comparable efficacy with lower cost and morbidity compared to nephrectomy. Ablative therapies may be used alone or in conjunction with surgery or chemotherapy for treatment of primary tumor and metastatic disease. Imaging plays a crucial role in pre-treatment selection and planning of ablation, intra-procedural guidance, evaluation for complications, short- and long-term post-procedural surveillance of disease, and treatment response. Treatment response and disease recurrence may differ considerably after ablation, particularly for stereotactic radiotherapy, when compared to conventional surgical and chemotherapies. This article reviews the current and emerging role of imaging for ablative therapy of renal cell carcinoma.

Computed Tomography-guided Core Needle Biopsy for Renal Tumors: A Review

Small renal tumors are sometimes challenging to diagnose accurately through imaging alone, and image-guided biopsies are performed when histological diagnoses are needed. Although ultrasound guidance is usually chosen for renal tumor biopsies, computed tomography guidance is preferred for selected cases; e.g., obese patients or when the target is undetectable by ultrasound (as those in the upper pole). In the 14 recently published studies covering ≥50 procedures, computed tomography-guided renal tumor biopsies had a wide range diagnostic yield (67.4%-97.4%). Complications often occurred; however, most were minor and asymptomatic. No biopsy-related deaths and tumor seeding occurred. This study aimed to review the advantages and disadvantages, procedure techniques, diagnostic yields, and complications of core needle biopsies for renal tumors under computed tomography guidance.

Microwave Ablation of Renal Cell Carcinoma

Management options for small renal masses include active surveillance, partial nephrectomy, radical nephrectomy, and thermal ablation. For tumors typically ≤3 cm in size, thermal ablation is a good option for those desiring an alternative to surgery or active surveillance, especially in patients who are considered high surgical risk. We favor microwave ablation because of the more rapid heating, higher temperatures that overcome the heat sink effect of vessels, reproducible cell kill, and a highly visible ablation zone formed by water vapor that corresponds well to the zone of necrosis. For central tumors, we favor cryoablation because of the slower formation of the ablation zone and less likelihood of damage to the collecting system. With microwaves, it is important to monitor the ablation zone in real time (ultrasound is the best modality for this purpose), avoid direct punctures of the collecting system, and to place probes tangential to the collecting system to avoid burning open a persistent tract between the urothelium and extrarenal spaces or causing strictures. The surgical steps described in this video cover our use of high-frequency jet ventilation with general anesthesia to minimize organ motion, initial imaging and targeting, probe insertion, hydrodissection (a technique that enables displacement of adjacent structures), the ablation itself, and finally our dressing. Postoperative cares typically consist of observation with a same-day discharge or an overnight stay. Follow-up includes a magnetic resonance imaging abdomen with and without contrast, chest X-ray, and laboratories (basic metabolic panel, complete blood count, and C-reactive protein) 6 months postablation. Overall, percutaneous microwave ablation is an effective and safe treatment option for renal cell carcinoma in both T1a and T1b tumors in selected patients with multiple studies showing excellent oncologic outcomes when compared with partial and radical nephrectomy.

Hemothorax After a Renal Biopsy With Ablation, a Rare Complication: A Case Report and Review of the Literature

Renal biopsy is an important diagnostic test which is used to extract kidney tissue with the help of a biopsy needle. It is frequently performed under ultrasonography or CT guidance. As with every other procedure, renal biopsy also carries some risks. Common complications of renal biopsy are damage to adjacent organs. Hemothorax is an exceedingly rare complication of renal biopsy. We report a case of a middle-aged female who developed a left-sided hemothorax after undergoing percutaneous renal biopsy with ablation and conducted a literature review of this rare complication.

Renal biopsies performed before versus during ablation of T1 renal tumors: implications for prevention of overtreatment and follow-up

Purpose

To assess the difference between renal mass biopsy (RMB) performed either before or during the ablation procedure.

Methods

A retrospective multicenter study was performed in patients with a cT1 renal mass treated with ablation between January 2007 and July 2019, including a search in the national pathology database for patients with a RMB planned for ablation. Patient and tumor characteristics and information on malignant, benign, and non-diagnostic biopsy results were collected to establish rates of overtreatment and number of ablations avoided in case of benign or non-diagnostic histology.

Results

RMB was performed in 714 patients, of which 231 patients received biopsy before planned ablation, and 483 patients at the time of ablation. Pathology results before ablation were malignant in 63% (145/231), benign in 20% (46/231) and non-diagnostic in 17% (40/231). Pathology results at the time of ablation were malignant in 67.5% (326/483), benign in 16.8% (81/483) and non-diagnostic in 15.7% (76/483), leading to a total of 32.5% of ablation of benign or non-diagnostic lesions. Of the patients with a benign biopsy obtained before ablation, 80.4% (37/46) chose not to undergo ablation. Patients with inconclusive biopsy before planned ablation chose an informed individualized approach including ablation, repeated biopsy, or no intervention in 56%, 34% and 10%.

Conclusion

This study emphasizes the importance of obtaining a biopsy prior to the ablation procedure in a separate session to lower the rate of potentially unnecessary ablations.

Contemporary Results and Clinical Utility of Renal Mass Biopsies in the Setting of Ablative Therapy: A single center experience

PURPOSE

Clinical guidelines have recently included renal mass biopsy (RMB) in management algorithms, especially in the setting of small renal masses ≤ 4 cm (SRM) and ablative therapy. We sought to evaluate the diagnostic rates of RMB, factors associated with a non-diagnostic biopsy, its clinical utility, and its safety profile in the setting of ablative therapy.

MATERIALS AND METHODS

A total of 174 RMB from 167 patients, performed in a tertiary academic center from 01/2015 to 01/2019, were included. Patient demographics, radiographic mass size, RMB diagnoses, subsequent clinical management, and complications were retrospectively reviewed. RMBs were classified as diagnostic or non-diagnostic based on set criteria.

RESULTS

The mean mass size was 3.0 cm (range: 0.5-15.3 cm) and 140 biopsies (80%) were SRM. Among all RMB, 159 (91%) were diagnostic and 15 (9%) were non-diagnostic. Non-diagnostic biopsies were associated with small mass size, the presence of a cystic component (p < 0.00001) and fewer number of cores submitted (p = 0.0046). All non-diagnostic biopsies occurred in SRMs, where the mean mass size was significantly smaller than diagnostic biopsies (1.3 versus 3.2 cm, p = 0.001). RMB with concurrent ablation yielded non-diagnostic results more frequently than isolated RMBs (15% vs 2%, respectively).

CONCLUSIONS

RMB is useful for definitive diagnosis and clinical management in the setting of ablative therapy. Small mass size, cystic lesions, and fewer number of passes obtained are associated with non-diagnostic biopsies. When a renal mass diagnosis is particularly critical, a separate biopsy procedure prior to ablative therapy is recommended.

CT and MR imaging surveillance of stage 1 renal cell carcinoma after microwave ablation

OBJECTIVE

To describe the CT and MR imaging findings after microwave ablation of clinical stage 1 renal cell carcinoma (RCC).

METHODS

This single-center retrospective study was performed under a waiver of informed consent. 49 patients (38 M/11F, mean age 66 ± 9.0) with 52 cT1a RCC and 19 patients (10M/9F, mean age 67 ± 9.7) with 19 cT1b RCC were treated with percutaneous microwave ablation between January 2012 and June 2014. The size and volume of the RCC and ablation zone were measured and the kidney, ablation zones and retroperitoneum were assessed at immediate post-procedure CT and surveillance CT and MRI.

RESULTS

Median imaging follow-up was 18 months (IQR 12-28). Ablation zones were heterogeneously hyperintense on T1W and hypointense on T2W MRI and hyperdense at CT. Thin peripheral, but no internal enhancement after contrast administration signified successful ablation zones. Ablation zones decreased in size, but did not resolve during surveillance. Immediate post-procedure subcapsular gas and hematoma (5/71, 7%) resolved prior to first follow-up. Focal, enhancing soft tissue within the ablation zone, invariably along the renal margin, signified local recurrence. Local recurrence rates were higher for T1b (2/19, 11%) compared to T1a (1/52, 2%). Urinomas (4/71, 6%) decreased in size and resolved during surveillance. Retroperitoneal fat necrosis (6/71, 9%), with opposed-phase loss of T1W MRI signal, was confirmed at histology after percutaneous biopsy.

CONCLUSION

CT and MR imaging features after microwave ablation of renal cell carcinoma are predictable and reliably demonstrate treatment success, early and delayed complications, and local recurrences that can guide patient management.

Computed tomography (CT)-guided percutaneous coaxial biopsy combined with microwave ablation for the treatment of renal masses

PURPOSE

This study aimed to investigate the feasibility, safety, and efficacy of computed tomography (CT)-guided percutaneous coaxial biopsy combined with microwave ablation (MWA) for the treatment of renal masses.

MATERIAL AND METHODS

The clinical data of ten patients (14 tumors) treated with CT-guided percutaneous coaxial biopsy combined with MWA from January 2017 to November 2019 were retrospectively analyzed. The patients were followed up for 2-33 months. The outcomes were evaluated with plain and contrast spiral CT scans. Renal function was assessed using the estimated glomerular filtration rate.

RESULTS

No severe MWA-related complication was observed. All the tumors were successfully ablated. There was no imaging evidence of local residual tumor, local tumor recurrence, or disease progression during the follow-up period.

CONCLUSIONS

CT-guided percutaneous coaxial biopsy combined with MWA might be an effective option for the diagnosis and treatment of renal masses in selected patients.

Is percutaneous image-guided renal tumour ablation ready for prime time?

In the last few decades, thermal ablation (TA) techniques have been increasingly applied to treat small localised renal cell carcinomas. Despite this trend, there is still an underuse of TA compared to surgery and a substantial lack of high-quality evidence derived from large, prospective, randomised controlled trials comparing the long-term oncologic outcomes of TA and surgery. Therefore, in this narrative review, we assess published guidelines and recent literature concerning the diagnosis and management of kidney-confined renal cell carcinoma to understand whether percutaneous image-guided TA is ready to be proposed as a first-line treatment.

Percutaneous renal biopsy: approach, diagnostic accuracy and risks

PURPOSE OF REVIEW

This article provides a review of recent advances and issues regarding the controversial topic of renal mass biopsy (RMB). The purpose of this review is to provide an update on the current status of renal biopsy based on recently published literature. Here, we particularly focus on articles that have been published within the last 12 months.

RECENT FINDINGS

The main topics covered in this review are the approach, diagnostic accuracy and risks related to RMB.

SUMMARY

Current literature suggests that improvements in both technique and technological advancements of RMB have led to greater diagnostic accuracy and low risks to the patient. Newer technologies are leading toward innovative and harmless ways to diagnose kidney cancer, including liquid and image-based biopsy. However, it appears that the question of whether or not to instate renal biopsy as standard clinical practice has remained a highly debated controversy.

Update on Indications for Percutaneous Renal Mass Biopsy in the Era of Advanced CT and MRI

OBJECTIVE. The objective of this article is to review the burgeoning role of percutaneous renal mass biopsy (RMB). CONCLUSION. Percutaneous RMB is safe, accurate, and indicated for an expanded list of clinical scenarios. The chief scenarios among them are to prevent treatment of benign masses and help select patients for active surveillance (AS). Imaging characterization of renal masses has improved; however, management decisions often depend on a histologic diagnosis and an assessment of biologic behavior of renal cancers, both of which are currently best achieved with RMB.

Tumor location does not impact oncologic outcomes for percutaneous microwave ablation of clinical T1a renal cell carcinoma

OBJECTIVE

To evaluate the impact of anterior tumor location on oncologic efficacy, complication rates, and procedure duration for 151 consecutive biopsy-proven clinical T1a renal cell carcinoma (RCC) treated with percutaneous microwave (MW) ablation.

METHODS

This single-center retrospective study was performed under a waiver of informed consent. One hundred forty-eight consecutive patients (103 M/45 F; median age 67 years, IQR 61-73) with 151 cT1a biopsy-proven RCC (median diameter 2.4 cm, IQR 1.9-3.0) were treated with percutaneous MW ablation between March 2011 and August 2017. Patient and procedural data collected included Charlson comorbidity index (CCI), RENAL nephrometry score (NS), use of hydrodisplacement, MW antennas/generator output/time, and procedure time (PT). Data were stratified by anterior, posterior, and midline tumor location and compared with the Kruskal-Wallis or chi-squared tests. The Kaplan-Meier method was used for survival analyses.

RESULTS

Tumor size, NS, and use/volume of hydrodisplacement were similar for posterior and anterior tumors (p > 0.05). Patients with anterior tumors had a higher CCI (3 vs 4, p = 0.001). Median PT for posterior and anterior tumors was similar (100 vs 108 min, p = 0.26). Single session technical success and primary efficacy were achieved for all 151 tumors including 61 posterior and 67 anterior tumors. The 4 (3%) Clavien III-IV complications and 6 (4%) local recurrences were not associated with tumor location (p > 0.05). Three-year RFS, CSS, and OS were 95% (95% CI 0.87, 0.98), 100% (95% CI 1.0, 1.0), and 96% (95% CI 0.89, 0.98), respectively.

CONCLUSIONS

The safety and efficacy of percutaneous microwave ablation for anterior and posterior RCC are similar.

KEY POINTS

• The safety profile for percutaneous microwave ablation of anterior and posterior T1a renal cell carcinoma is equivalent. • Percutaneous microwave ablation of T1a renal cell carcinoma provides durable oncologic control regardless of tumor location. • Placement of additional microwave antennas and use of hydrodisplacement are associated with longer procedure times.

A review of immune therapy in cancer and a question: can thermal therapy increase tumor response?

Immune therapy is a successful cancer treatment coming into its own. This is because checkpoint molecules, adoptive specific lymphocyte transfer and chimeric antigen T-cell (CAR-T) therapy are able to induce more durable responses in an increasing number of malignancies compared to chemotherapy. In addition, immune therapies are able to treat bulky disease, whereas standard cytotoxic therapies cannot treat large tumour burdens. Checkpoint inhibitor monoclonal antibodies are becoming widely used in the clinic and although more complex, adoptive lymphocyte transfer and CAR-T therapies show promise. We are learning that there are nuances to predicting the successful use of the checkpoint inhibitors as well as to specific-antigen adoptive and CAR-T therapies. We are also newly aware of a here-to-fore unrealised natural force, the status of the microbiome. However, despite better understanding of mechanisms of action of the new immune therapies, the best responses to the new immune therapies remain 20-30%. Likely the best way to improve this somewhat low response rate for patients is to increase the patient's own immune response. Thermal therapy is a way to do this. All forms of thermal therapy, from fever-range systemic thermal therapy, to high-temperature HIFU and even cryotherapy improve the immune response pre-clinically. It is time to test the immune therapies with thermal therapy in vivo to test for optimal timing of the combinations that will best enhance tumour response and then to begin to test the immune therapies with thermal therapy in the clinic as soon as possible.