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J Urol. 2017 Jul;198(1):12-21. doi: 10.1016/j.juro.2016.09.160. Epub 2017 Mar 9.

Bosniak Classification for Complex Renal Cysts Reevaluated: A Systematic Review.

Author information

1
Department of Radiology and Nuclear Medicine, Erasmus MC - University Medical Center Rotterdam, Rotterdam, the Netherlands. Electronic address: i.schoots@erasmusmc.nl.
2
Department of Urology, Erasmus MC - University Medical Center Rotterdam, Rotterdam, the Netherlands.
3
Department of Radiology and Nuclear Medicine, Erasmus MC - University Medical Center Rotterdam, Rotterdam, the Netherlands; Department of Epidemiology, Erasmus MC - University Medical Center Rotterdam, Rotterdam, the Netherlands; Harvard School of Public Health, Harvard University, Department of Health Policy and Management, Boston, Massachusetts.

Abstract

PURPOSE:

We systematically evaluated the Bosniak classification system with malignancy rates of each Bosniak category, and assessed the effectiveness related to surgical treatment and oncologic outcome based on recurrence and/or metastasis.

MATERIALS AND METHODS:

In a systematic review according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement and the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies) criteria, we selected 39 publications for inclusion in this analysis and categorized them into 1) surgical cohorts-all cysts treated surgically and 2) radiological cohorts-cysts with surgical treatment or radiological followup.

RESULTS:

A total of 3,036 complex renal cysts were categorized into Bosniak II, IIF, III and IV. In surgical and radiological cohorts pooled estimates showed a malignancy prevalence of 0.51 (0.44, 0.58) in Bosniak III and 0.89 (0.83, 0.92) in Bosniak IV cysts, respectively. Stable Bosniak IIF cysts showed a malignancy rate of less than 1% during radiological followup (surveillance). Bosniak IIF cysts, which showed reclassification to the Bosniak III/IV category during radiological followup (12%), showed malignancy in 85%, comparable to Bosniak IV cysts. The estimated surgical number needed to treat to avoid metastatic disease of Bosniak III and IV cysts was 140 and 40, respectively.

CONCLUSIONS:

The effectiveness of the Bosniak classification system for complex renal cysts was high in categories II, IIF and IV, but low in category III, and 49% of Bosniak III cysts was overtreated because of a benign outcome. This surgical overtreatment combined with the excellent outcome for Bosniak III cysts may suggest that surveillance is a rational alternative to surgery. This will require further study to assess whether surveillance of Bosniak III cysts will prove safe.

KEYWORDS:

classification; cysts; kidney; numbers needed to treat; treatment outcome

PMID:
28286071
DOI:
10.1016/j.juro.2016.09.160
[Indexed for MEDLINE]

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