Hypothesis: That, in men on surveillance for favorable risk prostate cancer treated with dutasteride, prostate specific antigen (PSA) kinetics is of value in identifying those men who harbor occult high grade prostate cancer.

The study will determine the prevalence of a secondary rise in PSA > 0.5 ng/ml and the PSA doubling time in subjects on surveillance being treated with dutasteride.

This analysis is a subset of the data associated with the active surveillance cohort at Sunnybrook Health Sciences Centre. Approximately 150 subjects within the cohort have received dutasteride therapy from 6 months to 3 years. All subjects have had serial PSAs at regular intervals between 3 to 6 months, and all have had a biopsy performed within 1 to 3 years of initiating dutasteride. The prevalence of a secondary rise in PSA > 0.5ng/ml will be calculated with the impact of dutasteride therapy on the PSA doubling time. This information will be correlated with baseline PSA value, prostate volume, extent of disease on initial biopsy and baseline PSA kinetics. PSA kinetics will be also correlated with Gleason score upgrading on repeat biopsy. The rate of negative biopsies in men on dutasteride therapy will be compared with a similar group of surveillance subjects not treated with dutasteride.

Inclusion Criteria:

• Patients on active surveillance for favorable risk prostate cancer who have been treated with dutasteride following the diagnosis of cancer.

Subjects are a subset of the men with prostate cancer on surveillance for favorable risk prostate cancer cohort