THE ACCURACY OF 250 FINE NEEDLE BIOPSIES OF RENAL TUMORS

Radiomics Machine Learning Analysis of Clear Cell Renal Cell Carcinoma for Tumour Grade Prediction Based on Intra-Tumoural Sub-Region Heterogeneity

BACKGROUND

Renal cancers are among the top ten causes of cancer-specific mortality, of which the ccRCC subtype is responsible for most cases. The grading of ccRCC is important in determining tumour aggressiveness and clinical management.

OBJECTIVES

The objectives of this research were to predict the WHO/ISUP grade of ccRCC pre-operatively and characterise the heterogeneity of tumour sub-regions using radiomics and ML models, including comparison with pre-operative biopsy-determined grading in a sub-group.

METHODS

Data were obtained from multiple institutions across two countries, including 391 patients with pathologically proven ccRCC. For analysis, the data were separated into four cohorts. Cohorts 1 and 2 included data from the respective institutions from the two countries, cohort 3 was the combined data from both cohort 1 and 2, and cohort 4 was a subset of cohort 1, for which both the biopsy and subsequent histology from resection (partial or total nephrectomy) were available. 3D image segmentation was carried out to derive a voxel of interest (VOI) mask. Radiomics features were then extracted from the contrast-enhanced images, and the data were normalised. The Pearson correlation coefficient and the XGBoost model were used to reduce the dimensionality of the features. Thereafter, 11 ML algorithms were implemented for the purpose of predicting the ccRCC grade and characterising the heterogeneity of sub-regions in the tumours.

RESULTS

For cohort 1, the 50% tumour core and 25% tumour periphery exhibited the best performance, with an average AUC of 77.9% and 78.6%, respectively. The 50% tumour core presented the highest performance in cohorts 2 and 3, with average AUC values of 87.6% and 76.9%, respectively. With the 25% periphery, cohort 4 showed AUC values of 95.0% and 80.0% for grade prediction when using internal and external validation, respectively, while biopsy histology had an AUC of 31.0% for the classification with the final grade of resection histology as a reference standard. The CatBoost classifier was the best for each of the four cohorts with an average AUC of 80.0%, 86.5%, 77.0% and 90.3% for cohorts 1, 2, 3 and 4 respectively.

CONCLUSIONS

Radiomics signatures combined with ML have the potential to predict the WHO/ISUP grade of ccRCC with superior performance, when compared to pre-operative biopsy. Moreover, tumour sub-regions contain useful information that should be analysed independently when determining the tumour grade. Therefore, it is possible to distinguish the grade of ccRCC pre-operatively to improve patient care and management.

Prospective evaluation of core number of biopsy for renal tumor: are multiple cores preferable?

PURPOSE

This single-center, single-arm, prospective, open-label study was conducted to evaluate the optimal number of cores (single or multiple) in renal tumor biopsy.

MATERIALS AND METHODS

Forty-four biopsies of 44 tumors (mean diameter, 2.7 ± 1.0 cm; range, 1.6-5.0 cm) were included. Biopsy was performed under ultrasound or computed tomography fluoroscopy guidance using an 18-gauge cutting needle and the co-axial method. Two or more specimens were obtained, which were divided into first and subsequent specimens. "First specimen" and "all specimens" were histologically evaluated (i.e., appropriateness of specimen, histological diagnosis, subtype, and Fuhrman grade of renal cell carcinoma [RCC]) blindly and independently by two board-certified pathologists.

RESULTS

Multiple specimens were successfully and safely obtained in all the biopsies. All tumors were histologically diagnosed; 40 malignancies included 39 RCCs and 1 solitary fibrous tumor, and 4 benign lesions included 2 angiomyolipomas, 1 oncocytoma, and 1 capillary hemangioma. In all RCCs, the subtype could be determined (32 clear cell RCCs, 4 chromophobe RCCs, and 3 papillary RCCs), and the Furman grade was determined in 38 RCCs. When only the first specimen was evaluated, 22.7% of the specimens were inappropriate for diagnosis, and 34 (77.3%) were histologically diagnosed. The diagnostic yield was significantly lower than that of all specimens (P = 0.0044). Univariate analysis revealed that smaller lesions were a significant predictor of diagnostic failure (P = 0.020).

CONCLUSION

Biopsy with multiple cores significantly improved diagnostic yield. Thus, operators should obtain multiple cores during renal tumor biopsy.

Diagnostics and prognostic evaluation in renal cell tumors: the German S3 guidelines recommendations

The German guidelines on renal cell carcinoma (RCC) have been developed at highest level of evidence based on systematic literature review. In this paper, we are presenting the current recommendations on diagnostics including preoperative imaging and imaging for stage evaluation as well as histopathological classification. The role of tumor biopsy is further discussed. In addition, different prognostic scores and the status of biomarkers in RCC are critically evaluated.

Percutaneous biopsy of small renal mass: can diagnostic accuracy be affected by hospital volume?

Introduction

High diagnostic performance and low morbidity for renal tumor biopsy (RTB) have been described in highly experienced centers. Here we present the five-year experience of our institute in performing RTB. The protocol used, the safety profile and the diagnostic accuracy obtained were analyzed.

Material and methods

The study is a retrospective single-institution clinical data review of 84 consecutive RTB of small renal masses. Post-biopsy complications were reported using the Clavien-Dindo system. To measure the concordance between biopsy and nephrectomy specimens regarding histological subtype and International Society of Urological Pathology/World Health Organization (ISUP/WHO) renal cell carcinoma grade, the kappa coefficient of Cohen was used.

Results

Median (IQR) follow-up time was 44 (29–58) months. In total, 94% of RTB procedures were free of complications; when complications did occur, 80% were grade I and 20% were grade II. No cases of tumor seeding were observed. Combining the first and repeated biopsies the overall diagnostic rate was 85.8%. Overall, 79.1% of diagnostic RTB were malignant. In 42 surgically treated patients, the concordance between the histological results of biopsies and surgical specimens was very good for histological subtypes (k = 0.87) and moderate for tumor grade (k = 0.51).

Conclusions

RTB resulted in a high safety profile. The overall diagnostic rate was 85% and an unnecessary intervention was avoided in 21% of patients. RTB showed a very good accuracy in determining the histological subtype of renal cancer while it was moderate for the tumor grade. These results are similar to those reported in larger series and support feasibility of this procedure in low-volume centers.

[Concordances and predictors of biopsies in renal tumors]

AIM

Evaluate the concordance between the renal lesions biopsy's histology and the final histology of the surgical specimen according to histological subtype, and search for predictive factors of non-concordance.

MATERIAL

We performed a monocentric retrospective study that included 156 patients suffering from a renal tumor that benefited a lesion biopsy before surgical treatment. Sensibility and specificity of the renal lesion's biopsy for histological diagnostic of the different renal tumors where calculated.

RESULTS

One hundred and fifty-eight renal tumor biopsies were realized between 2001 and 2016. One hundred and forty-three renal cell carcinoma were found on the surgical piece, 135 were diagnosed on prior biopsy. Global concordance rate was 88%. For the establishment of the nuclear Fuhrmann grade, the concordance rate (low vs. high grade) was 72.9%. The cohort was divided into 2 groups according to the existence (group 1, n=139) or the absence (group 2, n=19) of concordance. Group 1 and 2 differed by the predominance of men in group 1 (66% vs. 37%, P=0.013), distance between the sinus and the tumor above 4mm (65% vs. 42%, P=0.05).

CONCLUSION

In renal tumor care, renal biopsy is a reliable testing. However, some factors most likely linked to the tumor anatomy (intra-sinusal tumor) and their histological composition were involved in the lack of non-contribution to the diagnosis.

LEVEL OF EVIDENCE

4.

[CLINICAL CONSIDERATION OF PERCUTANEOUS RENAL BIOPSY FOR ADVANCED RENAL TUMOR]

(Objective) Advanced renal tumors are often difficult to diagnose based on radiological findings. The preset study aimed to evaluate the diagnostic efficacy and safety of percutaneous renal tumor biopsy in patients with advanced renal tumors. (Methods) Thirteen patients (6 males and 7 females) with advanced renal tumors who underwent percutaneous renal tumor biopsy between January 2015 and May 2017 were reviewed retrospectively. (Results) The median patients age was 69 years (range=40-81 years). The median renal tumor size was 91 mm (53-195 mm). Four cases were diagnosed as clear cell renal cell carcinoma (CCRCC), 8 as non-CCRCC, and 1 as malignant lymphoma prior to biopsy. Histopathological diagnoses after biopsy were CCRCC in 3, urothelial carcinoma in 3, and papillary renal cell carcinoma in 2 cases; there was 1 case each of chromophobe renal cell carcinoma, spindle cell RCC, carcinoma of the collecting ducts of Bellini, and nephroblastoma. Diagnosis could not be made in 1 case due to sampling error. Adverse events developed after renal tumor biopsy, with microscopic hematuria in 2 and pyrexia in 1 case. These were Grade 1 events according to the Clavien-Dindo Classification. Disseminated tumors were not observed during the follow-up period. (Conclusion) Percutaneous tumor biopsy for patients with advanced renal tumor is a safe procedure and useful for confirming the diagnosis pathologically before starting medication.

R.E.N.A.L. Nephrometry Score: A Preoperative Risk Factor Predicting the Fuhrman Grade of Clear-Cell Renal Carcinoma

Objective: The purpose of this study was to evaluate the efficacy and feasibility of the R.E.N.A.L. Nephrometry Score to postoperatively predict high-grade clear-cell renal carcinoma (ccRCC). Methods: The study included 288 patients diagnosed with ccRCC who had complete CT/CTA data and R.E.N.A.L. Nephrometry Scores and underwent renal surgery at our center between January 2012 and December 2015. The relationship between the pathological grade of renal masses and R.E.N.A.L. Nephrometry Score was evaluated. Results: Univariate analysis indicated that diagnostic modality, cystic necrosis, enlargement of the regional lymph node, distant metastasis, clinical T stage, TNM stage, surgical modality, tumor size, nearness of the tumor to the collecting system or sinus, total Nephrometry Score and individual anatomic descriptor components were significantly associated with postoperative tumor grade (P < 0.05). Multivariate analysis showed that tumor size, the maximal diameter (R score), exophytic/endophytic properties (E score) and the location relative to the polar lines (L score) were independent prognostic factors to preoperatively predicting ccRCC pathological grade. The areas under the ROC curve with respect to the multi-parameter regression model (0.935, 95%CI: 0.904-0.966), tumor size (0.901, 95%CI: 0.866-0.937), R score (0.868, 95%CI: 0.825-0.911), E score (0.511, 95%CI: 0.442-0.581) and L score (0.842, 95%CI: 0.791-0.892) were calculated and compared. Conclusion: Tumor size, as well as R, E, and L scores were independent prognostic factors for high-grade pathology. Lager tumor sizes and higher R, E and L scores were more likely to be associated with high-grade pathological outcomes. Thus, the R.E.N.A.L. Score is of practical significance in facilitating urologists to make therapeutic decisions.

Percutaneous radiofrequency ablation for renal cell carcinoma vs. partial nephrectomy: Comparison of long-term oncologic outcomes in both clear cell and non-clear cell of the most common subtype

OBJECTIVES

To compare the clinical outcomes of percutaneous radiofrequency ablation (PRFA) and partial nephrectomy (PN) in patients with clear cell renal cell carcinoma (ccRCC) and non-clear cell RCC (nccRCC) of the most common subtypes.

MATERIALS AND METHODS

A retrospective study was conducted to review the records of all the patients who underwent PRFA or PN between February 2005 and April 2014 at our institution. Patients with histologic confirmation of ccRCC, papillary RCC, and chromophobe RCC were included. The Mann-Whitney U test was applied to compare PRFA to PN in the ccRCC and nccRCC groups. The Kaplan-Meier method was used to generate the survival curves that were compared to the log-rank test.

RESULTS

A total of 264 patients meeting the selection criteria were included in this study. The tumor size ranged from 0.9 to 7.0cm. The median follow-up period was 78 months (range: 8-132 mo). Although PRFA provided comparable 10-year overall survival rates and 10-year disease-free survival (DFS) rates to PN both in ccRCC ≤4cm and nccRCC, the 10-year DFS for patients treated with PRFA was lower than that of PN in ccRCC >4cm. The DFS survival curve between the 2 operations and 2 subtypes was statistically significant in patients with tumor size >4cm. Limitations include retrospective review and selection bias.

CONCLUSIONS

Patients with T1b ccRCC treated with PRFA have less favorable outcomes than those with PN whereas PRFA provides comparable oncologic outcomes to PN in patients with T1b nccRCC. It is necessary to take RCC subtypes into consideration when choosing a surgical approach to treat T1b RCC between PFRA and PN.

Renal Tumor Biopsy Technique

Objective:

To review hot issues and future direction of renal tumor biopsy (RTB) technique.

Data Sources:

The literature concerning or including RTB technique in English was collected from PubMed published from 1990 to 2015.

Study Selection:

We included all the relevant articles on RTB technique in English, with no limitation of study design.

Results:

Computed tomography and ultrasound were usually used for guiding RTB with respective advantages. Core biopsy is more preferred over fine needle aspiration because of superior accuracy. A minimum of two good-quality cores for a single renal tumor is generally accepted. The use of coaxial guide is recommended. For biopsy location, sampling different regions including central and peripheral biopsies are recommended.

Conclusion:

In spite of some limitations, RTB technique is relatively mature to help optimize the treatment of renal tumors.

Systematic Review and Meta-analysis of Diagnostic Accuracy of Percutaneous Renal Tumour Biopsy

CONTEXT

The role of percutaneous renal tumour biopsy (RTB) remains controversial due to uncertainties regarding its diagnostic accuracy and safety.

OBJECTIVE

We performed a systematic review and meta-analysis to determine the safety and accuracy of percutaneous RTB for the diagnosis of malignancy, histologic tumour subtype, and grade.

EVIDENCE ACQUISITION

Medline, Embase, and Cochrane Library were searched for studies providing data on diagnostic accuracy and complications of percutaneous core biopsy (CB) or fine-needle aspiration (FNA) of renal tumours. A meta-analysis was performed to obtain pooled estimates of sensitivity and specificity for diagnosis of malignancy. The Cohen kappa coefficient (κ) was estimated for the analysis of histotype/grade concordance between diagnosis on RTB and surgical specimen. Risk of bias assessment was performed (QUADAS-2).

EVIDENCE SYNTHESIS

A total of 57 studies recruiting 5228 patients were included. The overall median diagnostic rate of RTB was 92%. The sensitivity and specificity of diagnostic CBs and FNAs were 99.1% and 99.7%, and 93.2% and 89.8%, respectively. A good (κ = 0.683) and a fair (κ = 0.34) agreement were observed between histologic subtype and Fuhrman grade on RTB and surgical specimen, respectively. A very low rate of Clavien ≥ 2 complications was reported. Study limitations included selection and differential-verification bias.

CONCLUSIONS

RTB is safe and has a high diagnostic yield in experienced centres. Both CB and FNA have good accuracy for the diagnosis of malignancy and histologic subtype, with better performance for CB. The accuracy for Fuhrman grade is fair. Overall, the quality of the evidence was moderate. Prospective cohort studies recruiting consecutive patients and using homogeneous reference standards are required.

PATIENT SUMMARY

We systematically reviewed the literature to assess the safety and diagnostic performance of renal tumour biopsy (RTB). The results suggest that RTB has good accuracy in diagnosing renal cancer and its subtypes, and it appears to be safe. However, the quality of evidence was moderate, and better quality studies are required to provide a more definitive answer.

Percutaneous renal tumour biopsy

The use of percutaneous renal tumour biopsy (RTB) as a diagnostic tool for the histological characterization of renal masses has increased dramatically within the last 30 years. This increased utilization has paralleled advances in imaging techniques and an evolving knowledge of the clinical value of nephron sparing surgery. Improved biopsy techniques using image guidance, coupled with the use of smaller gauge needles has led to a decrease in complication rates. Reports from series containing a large number of cases have shown the non-diagnostic rate of RTB to range from 4% to 21%. Re-biopsy has been shown to reduce this rate, while the use of molecular markers further improves diagnostic sensitivity. In parallel with refinements of the biopsy procedure, there has been a rapid expansion in our understanding of the complexity of renal cell neoplasia. The 2013 Vancouver Classification is the current classification for renal tumours, and contains five additional entities recognized as novel forms of renal malignancy. The diagnosis of tumour morphotype on RTB is usually achievable on routine histology; however, immunohistochemical studies may be of assistance in difficult cases. The morphology of the main tumour subtypes, based upon the Vancouver Classification, is described and differentiating features are discussed.

Indications for biopsy and the current status of focal therapy for renal tumours

The increased detection of small renal masses (SRMs) has focused attention on their uncertain natural history. The development of treatment alternatives and the discovery of biologically targeted drugs have also raised interest. Renal mass biopsies (RMBs) have a crucial role as they provide the pathological, molecular and genetic information needed to classify these lesions and guide clinical management. The improved accuracy has improved our knowledge of the behaviour of different tumour histologies and opened the potential for risk-adapted individualized treatment approaches. To date, studies have demonstrated that percutaneous ablation is an effective therapy with acceptable outcomes and low risk in the appropriate clinical setting. Although partial nephrectomy (PN) is still considered the standard treatment for SRM, percutaneous ablation is increasingly being performed and if long-term efficacy is sustained, it may have a wider application for SRMs after biopsy characterization.

EAU guidelines on renal cell carcinoma: 2014 update

CONTEXT

The European Association of Urology Guideline Panel for Renal Cell Carcinoma (RCC) has prepared evidence-based guidelines and recommendations for RCC management.

OBJECTIVES

To provide an update of the 2010 RCC guideline based on a standardised methodology that is robust, transparent, reproducible, and reliable.

EVIDENCE ACQUISITION

For the 2014 update, the panel prioritised the following topics: percutaneous biopsy of renal masses, treatment of localised RCC (including surgical and nonsurgical management), lymph node dissection, management of venous thrombus, systemic therapy, and local treatment of metastases, for which evidence synthesis was undertaken based on systematic reviews adhering to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Relevant databases (Medline, Cochrane Library, trial registries, conference proceedings) were searched (January 2000 to November 2013) including randomised controlled trials (RCTs) and retrospective or controlled studies with a comparator arm. Risk of bias (RoB) assessment and qualitative and quantitative synthesis of the evidence were performed. The remaining sections of the document were updated following a structured literature assessment.

EVIDENCE SYNTHESIS

All chapters of the RCC guideline were updated. For the various systematic reviews, the search identified a total of 10,862 articles. A total of 151 studies reporting on 78,792 patients were eligible for inclusion; where applicable, data from RCTs were included and meta-analyses were performed. For RCTs, there was low RoB across studies; however, clinical and methodological heterogeneity prevented data pooling for most studies. The majority of studies included were retrospective with matched or unmatched cohorts based on single or multi-institutional data or national registries. The exception was for systemic treatment of metastatic RCC, in which several RCTs have been performed, resulting in recommendations based on higher levels of evidence.

CONCLUSIONS

The 2014 guideline has been updated by a multidisciplinary panel using the highest methodological standards, and provides the best and most reliable contemporary evidence base for RCC management.

PATIENT SUMMARY

The European Association of Urology Guideline Panel for Renal Cell Carcinoma has thoroughly evaluated available research data on kidney cancer to establish international standards for the care of kidney cancer patients.

Diagnostic significance of biopsies in renal masses

Introduction

We investigated the reliability and mapping of percutaneous needle core biopsies in the kidney in histopathological diagnosis of renal masses particularly for those with suspicious radiologic appearance in an attempt to prevent unnecessary nephrectomies.

Material and methods

Overall, 96 cases were included in our study that underwent radical nephrectomy or partial nephrectomy due to renal mass between November 2007 – March 2010. Ex–vivo biopsies 1 cm apart were obtained from the peripheral region of the mass. Additionally, half of these peripheral biopsies were obtained from the central region of the mass. Diagnostic yield of the biopsy cores were correlated. Sensitivity and specificity of peripheral and central biopsies in differentiating benign and malignant tissues were calculated.

Results

Sensitivity and specificity in differentiating malignant lesions were 93% and 87%, and 90% and 93% for peripheral and central biopsies, respectively. Positive and negative predictive values were 97% and 68%, and 98% and 64% for peripheral biopsies and central biopsies, respectively. Hazard ratio for cigarette smoking and presence of necrosis on CT scans were 4.76 (CI 1, 6–14.3; p = 0.04) and 3.32 (CI 1,2–9.2; p = 0.017) and 3.71 (CI 1.3–10.7; p = 0.013) and 3,51 (CI 1.3–9.6; p = 0.012) for peripheral and central biopsies, respectively.

Conclusions

Kidney biopsies can be performed in suspicious renal masses of central and peripheral biopsies with similar efficacy.

Lessons learned from the comparative study between renal mass biopsy and the analysis of the surgical specimen

INTRODUCTION

The role of renal mass (RM) biopsy is currently under discussion. As a result of the progressive increase in the incidental diagnosis of RMs (which have a higher percentage of benignity and well-differentiated cancers), new approaches have emerged such as observation, especially with elderly patients or those with significant comorbidity. RM biopsy (RMB) should provide sufficient information for making this decision, but so far this has not been the case. We examine our prospective series of in-bench RMBs after surgery and compare them with the anatomy of the removed specimen.

MATERIAL AND METHODS

We obtained (prospectively, in-bench and with a 16-gauge needle) 4 biopsies of RMs operated on in our department from October 2008 to December 2009. These RMs were analyzed by 2 uropathologists and compared with the results of the specimen.

RESULTS

We analyzed 188 biopsies (47 RMs); 12.75% were "not valid". The ability of biopsy to diagnose malignancy or benignity was 100%, and the coincidence in the histological type was 95%. The success in determining the tumor grade was 100% when the cancer was low-grade and 62% when high-grade. None of the analyzed data (necrosis, size, etc.) influenced the results in a statistically significant manner.

CONCLUSION

RMB with a 16-G needle enables the differentiation between malignancy and benignity in 100% of cases, with a very similar diagnostic accuracy in the tumor type. Tumor grade is still the pending issue with renal mass biopsy.

Genitourinary cytopathology (kidney and urinary tract)

FNA of kidney masses have been performed for the diagnosis of mass lesions,confirmation of advanced neoplasia and metastases, and staging of tumors. In the past, the decision of whether to perform a nephrectomy used to be based on radiographic features and size, precluding the use of FNA. Today, where treatment is not limited to surgery alone, the indications for renal FNA have expanded. Most small renal masses are asymptomatic and are detected incidentally due to improved imaging techniques. Although most urologists agree that the standard of care for renal masses is surgery, if the patient is an elderly individual, or has comorbidities a preoperative FNA could be useful in guiding the management.When we look at data from large referral institutions such as Mayo Clinic, Johns Hopkins Medical Institutions, and the Cleveland Clinic approximately 30 %of the renal masses are benign [86---88]. Therefore, as astutely pointed out by Volpe et al.[3], there is a role for precise pretreatment characterization of the renal masses by FNA, which would decrease the unnecessary treatment for benign diseases and reduce the treatment-related mortality and morbidity in addition to reducing patient care costs.To date, urine cytology remains the gold standard for bladder cancer screening.It has been, and still is, the test against which all new tests are compared when evaluating potential bladder tumor markers. The answer to whether urine cytology possesses the optimal combination of sensitivity and specificity to retain consideration as the best screening device depends on the goals of the practice. Urine cytology has excellent specificity with only few false-positive cases. Its overall sensitivity (including both high grade and low grade lesions) is poor, but this is explained by poor criteria for identifying well-differentiated, low-grade urothelial carcinoma in cytology. The natural history of low grade lesions is that of multiple superficial recurrences in 70 - 80 % of patients, with only a minority ( 10-15 %)progressing to muscle invasive or metastatic disease [89]. Patients with low-grade urothelial carcinoma are at low risk for progression, they are monitored primarily for the development of a subsequent high grade tumor [90]. Therefore, as suggested by Koss, detection of new low-grade lesions may be clinically irrelevant as compared to early detection of disease progression [39]. Contrary to the low grade lesions, however, urine cytology often results in the identification of high-grade malignant cells even before a cystoscopically distinguishable gross lesion is present. In the last 20 years, a number of noninvasive test have been developed to detect urothelial carcinoma. Although some have been able to show a better sensitivity compared to cytology, only a few have been close to reaching the sensitivity seen in cytology. Most of these tests have not added much to the diagnostic evaluation. Combining some of the new markers with each other and/or cytologic evaluation may optimize their performance status.

Accuracy of determining small renal mass management with risk stratified biopsies: confirmation by final pathology

PURPOSE

We assess the accuracy of a biopsy directed treatment algorithm in correctly assigning active surveillance vs treatment in patients with small renal masses by comparing biopsy results with final surgical pathology.

MATERIALS AND METHODS

From 1999 to 2011, 151 patients with small renal masses 4 cm or smaller underwent biopsy and subsequent surgical excision. Biopsy revealed cell type and grade in 133 patients, allowing the hypothetical assignment of surveillance vs treatment using an algorithm incorporating small renal mass size and histological risk group. We compared the biopsy directed management recommendation with the ideal management as defined by final surgical pathology.

RESULTS

Biopsy called for surveillance of 36 small renal masses and treatment of 97 small renal masses. Final pathology showed 11 patients initially assigned to surveillance should have been assigned to treatment (8.3% of all patients, 31% of those recommended for surveillance), whereas no patients moved from treatment to surveillance. Agreement between biopsy and final pathology was 92%. Using management based on final pathology as the reference standard, biopsy had a negative predictive value of 0.69 and positive predictive value 1.0 for determining management. Of the 11 misclassified cases, 7 had a biopsy indicating grade 1 clear cell renal cancer which was upgraded to grade 2 (5) or grade 3 (2). After modifying the histological risk group assignment to account for undergrading of clear cell renal cancer, agreement improved to 97%, with a negative predictive value of 0.86 and a positive predictive value of 1.0.

CONCLUSIONS

Our results suggest that compared to final pathology, biopsy of small renal masses accurately informs an algorithm incorporating size and histological risk group that directs the management of small renal masses.

Utility of Renal Mass Biopsy in a UK Tertiary Referral Centre

Objective:

To determine the value of percutaneous biopsy in a UK cohort of patients with renal mass lesions, with particular reference to its utility for the prediction of histological cell-type, Fuhrman nuclear grade and necrosis.

Patients and methods:

From May 1999 to September 2009, 71 patients underwent renal mass biopsy (RMB), most for indeterminate renal masses or in those with a mass lesion and extrarenal malignancy. Approximately one-third were for small renal masses (≤4cm). Biopsy results were correlated with final surgical specimen pathology or with the outcome of surveillance in those not receiving surgery.

Results:

Of 71 biopsies, there were 65 (91.5%) considered diagnostic biopsies, of which 59 (90.8%) were malignant and 6 (9.2%) were benign. 30 patients with biopsy-proven malignancy underwent extirpative surgery, with a diagnostic accuracy for biopsy of 100%. Accuracy of RMB for histological sub-type, Fuhrman nuclear grade and tumour necrosis was 80.0%, 52.3% and 80.0%, respectively. Bleeding complications were seen in 2 (2.8%) patients, and there were no cases of needle track seeding.

Conclusion:

RMB is a safe and accurate method for determining underlying malignancy, with an acceptable non-diagnostic rate. Although concordance for histological tumour sub-type and necrosis was reasonable, values for nuclear grade were less reliable.

The cost-effectiveness of immediate treatment, percutaneous biopsy and active surveillance for the diagnosis of the small solid renal mass: evidence from a Markov model

PURPOSE

The most effective diagnostic strategy for the very small, incidentally detected solid renal mass is uncertain. We assessed the cost-effectiveness of adding percutaneous biopsy or active surveillance to the diagnosis of a 2 cm or less solid renal mass.

MATERIALS AND METHODS

A Markov state transition model was developed to observe a hypothetical cohort of healthy 60-year-old men with an incidentally detected, 2 or less cm solid renal mass, comparing percutaneous biopsy, immediate treatment and active surveillance. The primary outcomes assessed were the incremental cost-effectiveness ratio measured by cost per life-year gained at a willingness to pay threshold of $50,000. Model results were assessed by sensitivity analysis.

RESULTS

Immediate treatment was the highest cost, most effective diagnostic strategy, providing the longest overall survival of 18.53 life-years. Active surveillance was the lowest cost, least effective diagnostic strategy. On cost-effectiveness analysis using a societal willingness to pay threshold of $50,000 active surveillance was the preferred choice at a $75,000 willingness to pay threshold while biopsy and treatment were acceptable ($56,644 and $70,149 per life-year, respectively). When analysis was adjusted for quality of life, biopsy dominated immediate treatment as the most cost-effective diagnostic strategy at $33,840 per quality adjusted life-year gained.

CONCLUSIONS

Percutaneous biopsy may have a greater role in optimizing the diagnosis of an incidentally detected, 2 cm or less solid renal mass.

Is there a contemporary role for percutaneous needle biopsy in the era of small renal masses?

OBJECTIVE

To evaluate based on the best available data whether there is a contemporary role for percutaneous needle biopsy in the era of small renal masses.

PATIENTS AND METHODS

SRMs are acknowledged to be tumours less than 4cm and account for 48%-66% of new kidney cancers. Renal mass biopsy (RMB), traditionally limited to specific clinical scenarios and with inherent diagnostic accuracy problems has increased in popularity in recent years and is a potential valuable tool in the assessment of SRMs. Our discussion focuses on these issues. We performed a thorough Medline literature review using a combination of the following keywords; small renal mass, renal biopsy, percutaneous renal biopsy, renal mass biopsy and renal cell carcinoma. We identified the seminal articles with data/information pertaining to renal mass biopsy in small renal masses.

RESULTS

The facts that 1) a significant number of SRMs are diagnosed in an elderly patient cohort, 2) 20% of SRMs are benign on formal histology, 3) there are various management strategies now available and 4) modern RMB has a diagnostic accuracy >90% with few complications, are all reasons why there has been renewed interest in RMB.

CONCLUSION

  There is a contemporary role for RMB in the era of SRM as the incorporation of molecular profiling of tissue from RMB would augment our ability to risk stratify SRMs on an individual patient basis and adopt management accordingly. However, clinical judgement is paramount as there remains an unpredictable non-negligible risk of disease progression and metastasis whilst on surveillance.

Watchful waiting in the treatment of the small renal mass

Objectives:

To evaluate the role and feasibility of observation with regard to the small renal mass.

Methods:

We performed a literature search of MEDLINE, reviewing the world literature relevant to the natural history, role of percutaneous biopsy and surveillance of the small renal mass.

Results:

The average yearly growth rate of most small renal masses ranges from 0.1 to 0.70 cm/yr with obvious exceptions. Clinical predictors of growth such as radiographic size at presentation, age, gender and tumor characteristics are not reliable. Approximately 1% develops metastatic disease while under surveillance. Contemporary series of percutaneous biopsy of small renal masses report sensitivity for malignancy to be 90%-98%. However, false-negative results can occur. For the majority of patients, the gold standard remains surgical extirpation.

Conclusions:

Watchful waiting is an acceptable option for management of small renal masses in the surgically unfit and elderly population. More information regarding the natural history and metastatic potential of small renal masses is needed. Percutaneous needle biopsy can be successful in detecting malignancy in selected patients with small renal masses. The role of needle biopsy for the small renal mass continues to evolve

What is the added value of combined core biopsy and fine needle aspiration in the diagnostic process of renal tumours?

PURPOSE

Non-diagnostic results still hinder the routine use of core biopsy (CB) and fine needle aspiration (FNA) in the diagnostic process of renal tumours. Furthermore, substantial interobserver variability has been reported. We assessed the added value of combining the results of CB and FNA by five pathologists in the ex vivo diagnosis of renal mass.

METHODS

Two ex vivo core biopsies were taken followed by two FNA passes from extirpated tumours. All samples were evaluated by five blinded pathologists. A consensus diagnosis of the surgical specimen was the index for comparison. For each pathologist, the number of non-diagnostic (non-conclusive or undetermined biology and failed biopsies), correct and incorrect scored cases of each technique was assessed. When a non-diagnostic CB or FNA had a correct diagnostic counterpart, this was considered as of added value.

RESULTS

Of the 57 assessed tumours, 53 were malignant. CB was non-diagnostic in 4-10 cases (7-17.5%). FNA established the correct diagnosis in 1-7 of these cases. FNA was non-diagnostic in 2-6 cases (3.5-10.5%), and the counterpart CB established the correct diagnosis in 1-6 of these cases. For the 5 pathologists, accuracy of CB and FNA varied between 82.5-93% and 89.5-96.5%, respectively. Combination of both types of biopsy resulted in 55-57 correct results (accuracy 96.5-100%), i.e., an increase in accuracy of 3.5-14%.

CONCLUSION

Combining the result of CB and FNA in renal mass biopsy leads to a higher diagnostic accuracy. Recommendations on which technique used should be adapted to local expertise and logistic possibilities.

Accuracy of on-bench biopsies in the evaluation of the histological subtype, grade, and necrosis of renal tumours

AIMS

Few data are available on the diagnostic accuracy of kidney tumour biopsy.

METHODS

We sought to evaluate morphological diagnostic accuracy--such as histotype, Fuhrman grading, and necrosis--on a series of renal biopsies and matched whole tumours.

RESULTS

Among 56 renal tumours, the benign instances consisted of six oncocytomas (10.7%), one angiomyolipoma (AML; 1.8%), and one metanephric adenoma (1.8%). Malignant tumours consisted of clear cell renal cell carcinoma (RCC) in 37 cases (66.1%), papillary RCC in six cases (10.7%), chromophobe RCC in three cases (5.4%), and unclassified RCC in one case (1.8%). Core biopsies were conclusive in 53 cases (94.6%), identifying six (10.7%) benign and 47 (83.9%) RCCs. The accuracy in identifying histological subtype was 92%, and the concordance between core biopsies and surgical specimens was nearly perfect (κ = 0.858; p < 0.001). With regard to nuclear grade, the concordance index was only moderate (κ = 0.253) and the concordance between core biopsies and surgical specimens was fair (κ = 0.20; p = 0.11), such as for necrosis.

CONCLUSIONS

We concluded that the accuracy in identifying histological subtype is high. Tumours with oncocytic features are the most problematic for diagnosis. Results for nuclear grades and coagulative tumour necrosis are less convincing.

The role of biopsy in incidental renal tumours

PURPOSE

Historically, the biopsy of renal masses was not advocated, and to date there remains some controversy on the role of biopsy for renal masses in making treatment decisions. With the widespread use of imaging methods, the incidental diagnosis of renal masses has increased, necessitating renal biopsies to better plan the management of these tumours. Here I review previous reports to define the role of biopsy in incidental renal tumours.

METHODS

Data were obtained from English-language studies listed in PubMed on the use of renal biopsy for evaluating incidental solid small renal tumours.

RESULTS

The biopsy of small renal tumours is increasingly accepted due to: the increase in the incidence of small renal tumours; the finding that a significant number of these tumours are benign; the availability of new management options, such as ablative therapy and surveillance strategies; that imaging alone is unable to predict the biological behaviour of these tumours; and advances in the pathological evaluation of the biopsies. The biopsy procedure has an acceptable complication rate but is not free of limitations. The current recommendations for the use of renal biopsy in small renal tumours are: to help in differentiating benign from malignant renal tumours; before or during ablative therapies and during the follow-up after ablative therapies, for defining treatment success or failure; and to exclude nonrenal cell primary tumours (metastasis and lymphoma) or benign conditions (abscess), which may not require surgery.

CONCLUSIONS

The biopsy of small renal tumours is a safe and accurate procedure, and can help in the planning of definitive patient management.

The role of percutaneous renal biopsy in the management of small renal masses

The use of percutaneous renal mass biopsy (RMB) has increased in recent years, likely in parallel with the growing incidence of renal cell carcinoma and small renal masses in particular. Biopsy and imaging techniques are improving, and diagnostic sufficiency and accuracy of RMB now are much higher in large-volume, experienced centers. Overall morbidity is low. This has led to a significant expansion of the indications for biopsy beyond documenting renal involvement for patients with metastatic disease or other systemic illnesses. While there still are limitations to its use and clinical judgment is paramount, RMB is proving to be a valuable tool in the clinical diagnosis and management of small renal masses.

Feasibility of differential diagnosis of kidney tumors by comparative genomic hybridization of fine needle aspiration biopsies

The association of a genetic analysis that could improve the diagnostic accuracy of renal cell tumors in biopsy samples would allow better-informed therapeutic decisions. We performed comparative genomic hybridization (CGH) on an ex vivo fine-needle aspiration (FNA) biopsy and a tumor fragment obtained from 75 patients consecutively diagnosed with renal tumors and subjected to radical nephrectomy. The pattern of genomic changes by CGH was used blindly to classify the renal tumors and the genetic findings were subsequently compared with the histopathologic diagnosis. In particular cases, including in two carcinomas with morphologically distinct tumor areas, we performed FISH with several locus-specific probes, and looked for VHL point mutations, exonic rearrangements, or promoter methylation. CGH was successful in 82.7% FNA biopsies and in 96% tumor fragments, with the former allowing genetic diagnosis in 75% of renal cell tumors. The genetic and the initial histological classification differed in two renal neoplasias, but the genetic diagnosis was confirmed after review. The genetic pattern correctly diagnosed 93.5% of clear cell renal cell carcinomas (RCC), 61.5% of chromophobe RCC, 100% of papillary RCC, and 14.3% of oncocytomas, with the negative predictive value being 93.9, 90.7, 100, and 90.2%, respectively. The positive predictive value and specificity of copy number profiles was 100%. We demonstrate that genetic diagnosis by CGH on FNA biopsies can improve differential diagnosis in patients with kidney tumors.

Renal mass sampling: an enlightened perspective

Renal mass sampling (RMS) can be carried out by core biopsy or fine needle aspiration with each presenting potential advantages and limitations. The literature about RMS is confounded by a lack of standardized techniques, ambiguous terminology, imprecise definitions of accuracy, substantial rates of non-informative biopsies, and recurrent diagnostic challenges with respect to eosinophilic neoplasms. Despite these concerns, RMS has an expanding role in the evaluation and treatment of renal masses, in order to stratify biological aggressiveness and guide management that can range from surgery to active surveillance. Non-informative biopsies can be managed with surgical excision or repeat biopsy, with the latter showing encouraging results in recent studies. We propose a new classification in which all biopsies are categorized as non-informative versus informative, with the latter being subclassified as confirmed accurate, presumed accurate or confirmed inaccurate. This terminology will facilitate the comparison of results from various studies and stimulate progress. Incorporation of novel biomarkers and molecular fingerprinting into RMS protocols will likely allow for more rational management of patients with renal masses in the near future.

Biopsy of a renal mass: where are we now?

PURPOSE OF REVIEW

To review the most recent literature concerning renal mass biopsy with special consideration to three points: variation in results related to the standard used as comparison, biopsy in small renal masses (up to 4 cm in diameter) and the case for nondiagnostic biopsy.

RECENT FINDINGS

The overall rate of failed and indeterminate biopsies shows a trend for improvement. However, selection bias and the lack of a uniform index test for comparison preclude a definitive statement. Fine-needle aspiration may equal results of core biopsy, but its role in the diagnostic algorithm is not yet defined. In-vivo accuracy decreases in small renal masses with the same limitations exposed for the overall literature on renal mass biopsy. When nondiagnostic biopsies are considered, there is a need for standardization of the nomenclature in order to compare results. Re-biopsies or surgery after a nondiagnostic biopsy shows malignancy in up to 75% of the cases of renal cell carcinoma.

SUMMARY

There is a trend in increasing interest and accuracy on the subject of percutaneous biopsy of renal masses as well as a decreasing trend in the rate of nondiagnostic biopsies. In the small renal masses, most likely to be benign, a diagnostic percutaneous biopsy may have a definitive role. However, the higher rate of nondiagnostic results in this population calls for prospective studies with standard definitions and when possible homogenous index test to properly assess the diagnostic performance of the biopsy.