Gleason drift in the NIHR ProtecT study.

Aims: There is increasing evidence of Gleason score (GS) drift in prostatic core biopsies during the last two decades. The ProtecT study is a randomized controlled study and provides an excellent cohort to study the effect of time, prostate-specific antigen (PSA) level, perineural invasion, tumour length and age on GS. Methods and results: The ProtecT study recruited men in the United Kingdom between 1999 and 2010. The Gleason scores were grouped into four categories <= 3 + 3, 3 + 4, 4 + 3 and >= 4 + 4 for analysis. Data from England between 2000 and 2012 were also available. A total of 3282 biopsies containing cancer were analysed. For each year of the ProtecT study, the odds of being diagnosed with a higher GS category increased by 4.9%. Higher GS was also associated with perineural invasion, increasing tumour length, age and PSA level. While biopsy GS from England was incomplete, it also showed a marked decrease in GS five and six tumours during the same period. Conclusion: There was GS drift from 3 + 3 to 3 + 4 with time in the ProtecT study, but there appeared to be no significant change in percentage of GS 4 + 3 or higher. This drift was less dramatic when compared to GS in the rest of England.