Tag Archive for: Canadian Kidney Cancer information system


Article of the Week: Safety, reliability and accuracy of small renal tumour biopsies: results from a multi-institution registry

Every week the Editor-in-Chief selects an Article of the Week from the current issue of BJUI. The abstract is reproduced below and you can click on the button to read the full article, which is freely available to all readers for at least 30 days from the time of this post.

In addition to the article itself, there is an accompanying editorial written by a prominent member of the urological community. This blog is intended to provoke comment and discussion and we invite you to use the comment tools at the bottom of each post to join the conversation.

If you only have time to read one article this week, it should be this one.

Safety, reliability and accuracy of small renal tumour biopsies: results from a multi-institution registry

Patrick O. Richard*,, Michael A. S. Jewett*, Simon Tanguay, Olli Saarela§, Zhihui Amy Liu§, Frederic Pouliot, Anil Kapoor**, Ricardo Rendon†† and Antonio Finelli*


*Departments of Surgery and Surgical Oncology, Princess Margaret Cancer Centre, University Health Network and the University of Toronto, Toronto, ON, Canada, Centre Hospitalier Universitaire de Sherbrooke, Universite de Sherbrooke, Sherbrooke, QC, Canada, Department of Surgery, Division of Urology, McGill University Health Center, McGill University, Montreal§Dalla Lana School of Public Health, University of Toronto, Universite Laval, Centre de Recherche du Centre Hospitalier Universitaire de Quebec, Quebec **Department of Surgery, Division of Urology, McMaster University, Hamilton and ††QEII Health Sciences Centre, Department of Urology, Dalhousie University, Halifax, NS, Canada




To validate, in a multi-institution review, the safety, accuracy and reliability of renal tumour biopsy (RTB) and its role in decreasing unnecessary treatment.

Materials and Methods

We conducted a multi-institution retrospective study of patients who underwent RTB to characterize a small renal mass (SRM) between 2011 and May 2015. Patients were identified using the prospectively maintained Canadian Kidney Cancer information system. Diagnostic and concordance rates were presented using proportions, whereas factors associated with a diagnostic RTB were identified using a logistic regression model.



Of the 373 biopsied SRMs, the initial biopsy was diagnostic in 87% of cases. Of the 47 non-diagnostic biopsies, 15 had a repeat biopsy of which, 80% were diagnostic. When both were combined, therefore, a diagnosis was obtained in 91% of SRMs. Of these, 18% were benign. Size was the only factor found to be associated with achieving a diagnostic biopsy. RTB histology and nuclear grade (high or low) were found to be highly concordant with surgical pathology (86 and 81%, respectively). Of the discordant tumours (n = 16), all were upgraded from low to high grade on surgical pathology. Adverse events were rare (<1% of cases).


The present multi-institution study confirms that RTB of SRMs is safe, accurate and reliable across institutions, while decreasing unnecessary treatment. Given our findings, RTBs may be a helpful tool with which to triage SRMs and guide appropriate management.

Editorial: Renal tumour biopsy: let’s talk about it

There has been a marked increase in the incidental diagnosis of small renal masses (SRMs), resulting in overtreatment of benign and indolent lesions. Renal tumour biopsy (RTB) has received increasing attention as a potential tool to help reduce this overtreatment, with single-institution studies reporting good safety, accuracy, and reliability. One of the purposes of paper by Richard et al. [1], appearing in this issue of BJUI, was to address whether these results of RTB were generalisable across multiple institutions. They evaluated 373 RTBs from 12 centres, reporting an initial diagnostic rate of 87%, with 32% of non-diagnostic RTBs undergoing repeat biopsy, for a combined diagnostic rate of 91%. They reported concordance rates between RTB and surgical pathology of >80% and a RTB complication rate of <1%. The generalisability of these impressive RTB results remains unclear because they were unable to report the numbers of RTB per centre (beyond ‘at least one’) and results were likely driven by a few high-volume centres.

The analysis is not without limitations. The negative predicative value (NPV) of RTB could not be assessed because there was no surgical specimen to confirm a benign RTB diagnosis. A meta-analysis by Patel et al. [2] raised concerns about a non-diagnostic or negative RTB. Of the 14% of patients with a non-diagnostic biopsy, 90% of those subsequently undergoing surgery were found to have cancer. Among patients having surgery, 37% with a negative biopsy who underwent surgical extirpation were found to have cancer on final pathology (NPV 63%). Another limitation of RTBs is that they tend to under grade tumours compared to surgical pathology. Even when using a simplified two-tiered grading system of low vs high grade tumours to improve concordance [3], 20% of patients with low-grade clear cell RCC (ccRCC) were upgraded to high-grade ccRCC at surgery. Concordance rates did not include non-diagnostic biopsies; nonetheless, their results support that a ‘good’ RTB can usually be trusted. Selection bias may have been a factor because patients who did not receive a RTB for a SRM were not included. It seems unlikely that reports of improved RTB outcomes would result in a change in guidelines to a ‘one size fits all’ policy recommending RTB in all patients with a SRM. RTB may not be feasible in some patients (anterior, hilar, cystic tumours) and may not always have potential to change clinical management, such as with a young healthy patient who is unwilling to accept any degree of uncertainty with a negative biopsy or an elderly patient with comorbidities who would not accept treatment regardless of RTB results. In this study [1], only ~25% of the patients who underwent surgery for a cT1a lesion had a RTB before surgery, possibly a reflection of the limitations of RTB, as well as some room for improvement.

Despite the limitations of RTB, the fact remains that many renal lesions are over treated, RTB outcomes are improving, and RTB may help guide clinical management. The authors [1] suggest that even a misclassified SRM could probably be managed conservatively over the short term. They recommend that even a benign RTB should be followed with serial imaging and that a repeat RTB should be considered for fast growing lesions. Perhaps the future of RCC diagnosis lies beyond the RTB and includes imaging innovations that can distinguish benign and malignant tumours and spare patients an unnecessary treatment, as well as an unnecessary biopsy. For example, Gorin et al. [4] showed that technetium-99m (99mTc)-sestamibi single-photon emission CT (SPECT)/CT could accurately distinguish renal oncocytomas and hybrid oncocytic/chromophobe tumours from other renal tumour histologies.

Current guidelines already acknowledge the potential role for RTB to guide clinical management in patients willing to accept the known limitations and who have an indeterminate SRM or are considering a range of treatment options such as active surveillance or ablation. We do not need a blanket guideline mandating upfront RTB for all. But we should at least talk about RTB with our patients with SRMs. We owe it to them to be aware of the potential benefits and limitations of RTB and include this in our discussion so they can be involved in the decision.

Haider Rahbar, and Craig Rogers


Vattikuti Urology Institute, Henry Ford Hospital, Detroit, MI, USA






3 Rioux-Leclercq N, Karakiewicz PI, Trinh QD et al. Prognostic ability of simplied nuclear grading of renal cell carcinoma. Cancer 2007; 109: 86874



© 2024 BJU International. All Rights Reserved.