European Urology

Letters to the Editor published online

I read with great interest the article by Drs. Crispen and Blute in the February 2009 issue of European Urology [1]. I would like to comment on the article, as several questions arose after reading the study.

First, the authors stated that thermal ablation therapies such as cryoablation and radiofrequency ablation were frequently undertaken without pathologic evaluation of renal tumors. Recent studies, however, have reported that almost 100% of renal tumors were histologically confirmed prior to the use of ablation therapies [2], and [3] because a benign diagnosis is more likely in small renal tumors (≤3 cm) than in larger tumors [4]. Therefore, a renal mass biopsy is needed to prevent patients from undergoing unnecessary treatments including ablation or surgery. Once a renal tumor is thermally ablated, periodic follow-up examinations should be performed as if the lesion were cancerous.

Second, the authors stated that insufficient or inconclusive biopsy results range widely. A relatively high failure rate of a renal tumor biopsy results mainly from technical problems including operator experience, small lesion size, difficult targeting, fewer core tissues, inadequate specimens, and inadequate guiding modality [5]. The accuracy of a renal mass biopsy may be improved when these technical problems are sufficiently evaluated before the biopsy procedure. Even though an initial renal tumor biopsy is inconclusive, repeated biopsies are recommended to obtain a definite diagnosis. Despite biopsy failure to confirm a pathologic diagnosis, most of the inconclusive lesions remain stable in size and do not rapidly grow or metastasize during the follow-up period [5].

Last, the authors stated that renal mass biopsy results did not affect treatment strategies. A renal mass biopsy is frequently performed for the following indications. A percutaneous biopsy may be useful in patients who have limited life expectancy or severe comorbidities [4]. Even when the renal tumor is malignant, aggressive approaches to the treatment for these patients may increase the risk of morbidity or mortality. In patients with an extrarenal malignant tumor, a substantial number of solitary renal tumors may be metastatic [4]. If multifocal renal tumors are detected without evidence of an extrarenal malignancy, two probable diagnoses are renal cell carcinomas or oncocytomas [4]. A renal mass biopsy is essential in these cases for avoiding high postoperative morbidity or deciding cancer staging and treatment plan. Therefore, a renal mass biopsy can affect treatment strategies in these clinical settings.

It is hoped that the responses of the authors may help readers to understand renal mass biopsy better and be useful to those wishing to perform a biopsy prior to ablation or surgery.
Conflicts of interest: The author has nothing to disclose.