Podium Session

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PD11-06: Cystic Renal Masses: Is the Bosniak classification system an adequate predictor of survival?

Friday, May 12
1:50 PM - 2:00 PM
Location: BCEC: Room 251

Presentation Authors: Thenappan Chandrasekar*, Ardalan E. Ahmad, Kamel Fadaak, Michael A.S. Jewett, Antonio Finelli, Toronto, Canada

Introduction: We evaluate intervention rates and survival outcomes of complex renal cysts in a single center experience. Outcomes stratified by initial classification according to the Bosniak classification system.

Methods: We used a radiology data-mining system (Montage; Montage Healthcare Systems, Philadelphia, PA, USA) to retrospectively review the radiology database in an academic health center between 2001 and 2013 to identify all cases of "complex cyst." Primary end points were overall (OS) and cancer specific survival (CSS).

Results: 248 patients were identified using the Montage system to have radiographic reports of complex renal cysts. Of these, 141 (56.9%), 86 (34.7%), and 21 (8.4%) had Bosniak 2F, 3 and 4 cysts, respectively. Median follow-up was 66.05±54.24 months with an average of 3.61 scans (all modalities) per year. Of the 244 patients for whom we had follow-up, there were no cancer-specific deaths and overall mortality was 7.4%. Only 1 patient (4.7%) with a Bosniak 4 lesion at diagnosis developed metastases during follow-up. 20 patients underwent percutaneous biopsy of a solid nodule within the cyst; 7 (35%) were found to have renal cell carcinoma, and all of these patients received treatment. With regards to intervention, 6 (4.3%), 31 (36.0%) and 13 (61.9%) of the Bosniak 2F, 3 and 4 patients underwent either surgical or ablative intervention, respectively. Indication for intervention was predominantly age (median age: intervention 50.3±14.6, no intervention 63.4±13.3). Median time to intervention from initial identification was 6.45 months. Extirpative surgery with radical (17 patients, 34%) or partial nephrectomy (30 patients, 60%) was the predominant intervention, while 3 patients (6%) underwent ablation. While 4 patients (8.5%) had benign final pathology, the remainder had RCC: 23 (48.9%) clear cell RCC, 10 (21.2%) multilocular cystic RCC, 7 (14.9%) papillary type 1 RCC, 3 (6.4%) papillary type II RCC and 1 (2.1%) tubulocystic RCC. The majority (95.1%) were Fuhrman grade 1 or 2; 2 patients (4.9%) were Fuhrman grade 3. None of the patients undergoing intervention had evidence of recurrence during follow-up. Even when excluding patients undergoing intervention, CSS remained 100%.

Conclusions: Cancer-specific survival and overall survival for patients diagnosed with Bosniak 2F-4 complex renal cysts remains quite high; there were no cancer-specific deaths, even in the group that received no intervention. Reconsideration of management guidelines for complex renal cysts based on Bosniak classification system is warranted, particularly for Bosniak 3 cysts.

Source Of Funding: None

Thenappan Chandrasekar, MD

University of Toronto

Thenappan Chandrasekar, MD is a Society of Urologic Oncology (SUO) first-year clinical fellow at the University of Toronto, Toronto, ON, Canada. He completed medical school at Sidney Kimmel Medical College (formerly Jefferson Medical College), Philadelpha, PA, USA and urology residency training at UC Davis Medical Center, Sacramento, CA, USA.

With an interest in the multidisciplinary management of urologic malignancies, and in particular bladder and kidney cancer, he is looking to return to the US in 2018 for a career in urologic oncology.


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PD11-06: Cystic Renal Masses: Is the Bosniak classification system an adequate predictor of survival?

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