Recent trends in Gleason grading of prostate cancer: I. Pattern interpretation.

Histologic grading remains the most useful tissue-based predictor of prognosis of prostate cancer. The Gleason system is now the only grading system recommended by the World Health Organization (WHO) for prostatic carcinoma. In recent years, there has been a gradual shift of how the Gleason grading is applied in practice. There has been a general trend toward upgrading of prostate cancer. A consensus conference was organized in 2005 by the International Society of Urological Pathology with the purpose to standardize both the perception of histologic patterns and how grade information is compiled and reported. The recommendations regarding pattern interpretation are summarized and discussed in this review.