Elsevier

European Urology

Volume 68, Issue 6, December 2015, Pages 1007-1013
European Urology

Platinum Priority – Kidney Cancer
Editorial by Umberto Capitanio and Alessandro Volpe on pp. 1014–1015 of this issue
Renal Tumor Biopsy for Small Renal Masses: A Single-center 13-year Experience

https://doi.org/10.1016/j.eururo.2015.04.004Get rights and content

Abstract

Background

Renal tumor biopsy (RTB) for the characterization of small renal masses (SRMs) has not been widely adopted despite reported safety and accuracy. Without pretreatment biopsy, patients with benign tumors are frequently overtreated.

Objective

To assess the diagnostic rate of RTBs, to determine their concordance with surgical pathology, and to assess their impact on management.

Design, setting, and participants

This is a single-institution retrospective study of 529 patients with biopsied solid SRMs ≤4 cm in diameter. RTBs were performed to aid in clinical management.

Outcome measurements and statistical analysis

Diagnostic and concordance rates were presented using proportions. Factors that contributed to a diagnostic biopsy were identified using a multivariable logistic regression.

Results and limitations

The first biopsy was diagnostic in 90% (n = 476) of cases. Of the nondiagnostic biopsies, 24 patients underwent a second biopsy of which 83% were diagnostic. When both were combined, RTBs yielded an overall diagnostic rate of 94%. Following RTB, treatment could have been avoided in at least 26% of cases because the lesion was benign. Tumor size and exophytic location were significantly associated with biopsy outcome. RTB histology and nuclear grade were highly concordant with final pathology (93% and 94%, respectively). Adverse events were low (8.5%) and were all self-limited with the exception of one. Although excellent concordance between RTB and final pathology was observed, only a subset of patients underwent surgery following biopsy. Thus it is possible that some patients were misdiagnosed.

Conclusions

RTB of SRMs provided a high rate of diagnostic accuracy, and more than a quarter were benign. Routine RTB for SRMs informs treatment decisions and diminishes unnecessary intervention. Our results support its systematic use and suggest that a change in clinical paradigm should be considered.

Patient summary

Renal tumor biopsy (RTB) for pretreatment identification of the pathology of small renal masses (SRMs) is safe and reliable and decreases unnecessary treatment. Routine RTB should be considered in all patients with an indeterminate SRM for which treatment is being considered.

Introduction

The incidence of kidney cancer is increasing, primarily due to an increase in the detection of small renal masses (SRMs) that are often early stage renal cell carcinomas (RCCs) [1]. This is thought to be in large part related to the greater use of abdominal imaging [2].

Surgical treatment of stage pT1a RCC produces excellent cancer-specific survival rates [3]. Most are incidentally detected as SRMs that are usually solid enhancing masses on imaging and concerning for malignancy [2]. There are currently no clinical or radiographic features that accurately predict histologic diagnosis. Hence surgical series have shown that 20–30% of SRMs are benign on final pathology. Moreover, SRMs found to be malignant are usually of lower nuclear grade than their larger counterparts [4].

Renal tumor biopsies (RTBs) have been proposed as a safe and useful tool for the pretreatment identification of benign tumors. The goal of RTB is to avoid the potential morbidity associated with overtreatment of SRMs [5], [6], [7], [8]. Despite their potential benefits, RTBs have not been widely adopted in the management of SRMs [9]. The lag in uptake is likely due to concerns regarding the lack of sufficient tissue for diagnosis, discordance with final pathology, safety, and, most importantly, the lack of perceived impact on clinical management. Several, albeit generally small, studies suggest that these concerns were exaggerated [5], [6], [7], [8]. However, large series that demonstrate the benefits of RTB are currently lacking.

In this study, we described the largest single-institution experience with RTB of SRMs, explored factors associated with diagnostic success, and assessed the impact of RTB on clinical management.

Section snippets

Patient selection

This retrospective single-center study was approved by the institutional review board. Subjects who underwent an RTB for a radiologically indeterminate SRM between January 2001 and December 2013 were identified through a prospectively maintained database. A chart review was completed to abstract periprocedural complications and to exclude predominantly cystic lesions as well as RTBs that were not performed with the objective of aiding treatment planning.

A total of 705 RTBs performed in patients

Results

A total of 529 biopsied SRMs in 509 patients were included in the analysis. The initial biopsy was diagnostic in 90% (n = 476). Of these, 26% (n = 123) were of benign histology. The patient, procedure, and lesion characteristics of initial diagnostic and nondiagnostic biopsies are compared in Table 1. Of the 53 nondiagnostic RTBs, a rebiopsy was performed in 24 masses (45%) and was diagnostic in 83% (n = 20) of them (Fig. 1). Therefore, the overall diagnostic rate when the first and second RTBs were

Discussion

Despite a growing body of evidence, the merits and safety of pretreatment biopsy continue to be debated. This study focused on RTB of SRMs as an aid to treatment decision making. To the best of our knowledge, it is the largest single-institution cohort published on SRM biopsy. We have demonstrated a 90% diagnostic rate with an initial biopsy and an 83% diagnostic rate after a rebiopsy for initially nondiagnostic RTB. Thus RTBs led to a diagnosis in 94% of patients with SRMs when the outcomes

Conclusions

Although the evidence in favor of routine RTB to characterize SRMs is compelling, critics have continued to argue against the practice because of the previously enumerated concerns. Our results demonstrate that each of these concerns is exaggerated. In view of our results, it seems difficult to continue to justify a timid uptake of routine SRM biopsies and the use of this information to implement treatment strategies. Indeed RCC is one of the very few tumors where indications for surgery are

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