SIU 2017: Contemporary Surgical Management of Renal Oncocytomas in the UK: BAUS National Audit Data from 2013 to 2015

Lisbon, Portugal ( Renal oncocytomas are a benign renal histology that is thought to encompass up to 10-20% of all renal lesions, particularly smaller solid renal masses. However, due to historical literature suggesting that renal oncocytoma cannot be differentiated from RCC based on imaging, British guidelines recommend surgical excision. However, the authors of this paper wanted to assess British surgeons’ practices regarding the management of oncoctyoma.

To do so, they conducted a retrospective review of the BAUS surgical registry for any patients with final nephrectomy pathology of oncocytoma over a 2 year period (2013-2015). The goal was to assess clinical practice (biopsy, surgical approach) and selected outcomes (complications, 30-day mortality). 

Out of ~24K nephrectomies, 680 had oncocytoma on final pathology (3.7%). Median size of the tumor was 4.2 cm; of those biopsied (n=22), median size was 3.8 cm. The majority were pT1 on final pathology, though there were 19 patients with pT3/4!

In terms of biopsy, the diagnostic yield was not ideal. 50% had benign pathology on biopsy, but ~25% had malignant histology. My concern with these results in conjunction with the high pT3/pT4 rate is that there is undiagnosed malignancy that may confuse the results.

Despite have primarily pT1/2 disease with median size of 4 cm, radical nephrectomy was the most common operation (56%). Partial nephrectomy was utilized in only 41%. Laparoscopy was the predominant approach.

In terms of complications, 39 patients had Grade 3-5 Clavien-Dindo complications. Overall complication rate was not benign – 21% had some complication during the perioperative course. 30-day mortality was very low at 0.3%, but still higher than one would expect with a benign histology. 

The conclusions that the authors draw, which we completely agree with, are:

1) Many of these patients with small renal masses (median size 4 cm) and benign final histology could have been managed expectantly on active surveillance
2) With a 21% rate of complications and 0.3% 30-day mortality, unnecessary surgery comes with significant cost in this population
3) Biopsy was underutilized. Increased utilization may have helped avoid unnecessary surgery.

Importantly, the biggest limitation is that only patients with oncocytoma on final surgical pathology were included. However, as most patients were recommended for surgical excision in this population, the capture was likely pretty good. In theory, patients untreated (ie biopsy and active surveillance) would not have been captured.

Presented by: Joana B Neves

Affiliation: British Association of Urologic Surgeons

Written by: Thenappan Chandrasekar, MD, Clinical Fellow, University of Toronto, Twitter: @tchandra_uromd at the 37th Congress of Société Internationale d’Urologie - October 19-22, 2017- Lisbon, Portugal
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