An increase in Gleason 6 tumour volume while on active surveillance portends a greater risk of grade re-classification with further follow-up.

We evaluated the relative risk of later grade re-classification and outcomes of patients who developed high-volume Gleason 6 prostate cancer (PCa) while on active surveillance (AS).

A prospectively maintained database was used to identify patients on AS between 1998 and 2013.

Tumour volume was assessed based on number of positive cores and proportion of core involvement. Chi-square and Fisher's exact test were used for analysis where appropriate. The primary endpoint was development of grade re-classification, defined as grade only and/or grade and volume at the event biopsy.

A total of 555 men met study inclusion criteria. Mean follow-up was 46 months. Overall, 70 patients demonstrated an increase in tumour volume at or after their second biopsy (B2). In comparison to those never experiencing volume or grade re-classification, prostate-specific antigen at diagnosis was not significantly different (p=0. 95), but median prostate volume was smaller in patients who demonstrated volume re-classification (p

While Gleason 6 PCa has a favourable natural history, it appears that AS patients who experience volume re-classification are at a substantially higher risk of developing grade re-classification. Thus, urologists should pay close attention to tumour core involvement and monitoring should be adjusted accordingly for early volume re-classification in younger men and in good health.

The Journal of urology. 2015 Sep 25 [Epub ahead of print]

Maria Komisarenko, Lih-Ming Wong, Patrick O Richard, Narhari Timilshina, Ants Toi, Andrew Evans, Alexandre Zlotta, Girish Kulkarni, Robert Hamilton, Neil Fleshner, Antonio Finelli

Department of Uro-oncology, Division of Surgical Oncology, Princess Margaret Cancer Center, University Health Network, Toronto, Canada. , Department of Urology, St Vincent's Hospital, Melbourne, Australia, Toronto, Canada. , Department of Uro-oncology, Division of Surgical Oncology, Princess Margaret Cancer Center, University Health Network, Toronto, Canada. , Department of Uro-oncology, Division of Surgical Oncology, Princess Margaret Cancer Center, University Health Network, Toronto, Canada. , Department of Uro-oncology, Division of Surgical Oncology, Princess Margaret Cancer Center, University Health Network, Toronto, Canada. , Department of Pathology, Toronto General Hospital, University of Toronto, Canada, Toronto, Canada. , Department of Uro-oncology, Division of Surgical Oncology, Princess Margaret Cancer Center, University Health Network, Toronto, Canada. , Department of Uro-oncology, Division of Surgical Oncology, Princess Margaret Cancer Center, University Health Network, Toronto, Canada. , Department of Uro-oncology, Division of Surgical Oncology, Princess Margaret Cancer Center, University Health Network, Toronto, Canada. , Department of Uro-oncology, Division of Surgical Oncology, Princess Margaret Cancer Center, University Health Network, Toronto, Canada. , Department of Uro-oncology, Division of Surgical Oncology, Princess Margaret Cancer Center, University Health Network, Toronto, Canada. 

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