Validation of a contemporary prostate cancer grading system using prostate cancer death as outcome.

Gleason scoring (GS) has major deficiencies and a novel system of five grade groups (GS⩽6; 3+4; 4+3; 8; ⩾9) has been recently agreed and included in the WHO 2016 classification. Although verified in radical prostatectomies using PSA relapse for outcome, it has not been validated using prostate cancer death as an outcome in biopsy series. There is debate whether an 'overall' or 'worst' GS in biopsies series should be used.

Nine hundred and eighty-eight prostate cancer biopsy cases were identified between 1990 and 2003, and treated conservatively. Diagnosis and grade was assigned to each core as well as an overall grade. Follow-up for prostate cancer death was until 31 December 2012. A log-rank test assessed univariable differences between the five grade groups based on overall and worst grade seen, and using univariable and multivariable Cox proportional hazards. Regression was used to quantify differences in outcome.

Using both 'worst' and 'overall' GS yielded highly significant results on univariate and multivariate analysis with overall GS slightly but insignificantly outperforming worst GS. There was a strong correlation with the five grade groups and prostate cancer death.

This is the largest conservatively treated prostate cancer cohort with long-term follow-up and contemporary assessment of grade. It validates the formation of five grade groups and suggests that the 'worst' grade is a valid prognostic measure.British Journal of Cancer advance online publication, 21 April 2016; doi:10.1038/bjc.2016.86 www.bjcancer.com.

British journal of cancer. 2016 Apr 21 [Epub ahead of print]

Daniel M Berney, Luis Beltran, Gabrielle Fisher, Bernard V North, David Greenberg, Henrik Møller, Geraldine Soosay, Peter Scardino, Jack Cuzick

Department of Molecular Oncology, Barts Cancer Institute, Queen Mary University of London, EC1A 7BE London, UK., Department of Molecular Oncology, Barts Cancer Institute, Queen Mary University of London, EC1A 7BE London, UK., UK Center for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, EC1A 7BE London, UK., UK Center for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, EC1A 7BE London, UK., National Cancer Registration Service (Eastern Office), Public Health England, CB22 3AD Cambridge, UK., Cancer Epidemiology and Population Health, King's College London, SE1 9RT London, UK., Department of Pathology, Queen's Hospital, Romford, RM7 0AG Essex, UK., Department of Urology, Memorial Sloan-Kettering Cancer Center, New York, 10065 NY, USA., UK Center for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, EC1A 7BE London, UK.