Dedifferentiation of prostate cancer grade with time in men followed expectantly for stage T1C disease

Purpose: We assess whether the Gleason grade changes in men followed expectantly with clinical stage T1c prostate cancer. Material and Methods: We studied 70 men with stage T1c prostate cancer who underwent watchful waiting with repeat needle biopsy sampling to assess for progression. After the initial cancer diagnosis all men had at least 1 other biopsy demonstrating cancer. Results: Of 70 cases 9 (12.9%) showed a significant change in grade from Gleason scores 6 or less to 7 or greater. The average followup of those patients without a change in grade was 22 months and greater than those with a change in grade. There was no difference between the groups with and without changes in grade in regard to initial prostate specific antigen (PSA), percent-free PSA, or PSA density or velocity. Of 9 cases there were 5 (56%) and 8 (89%) with grade change that occurred at 12 and 15 months or less after initial biopsy, respectively. In contrast, only 1 of 24 (4%) patients in whom last re-biopsy was performed 24 months or greater after the initial cancer diagnosis had a change in grade. Of the 21 men who underwent radical prostatectomy 5 (24%) had worsening of grade on the radical prostatectomy specimen compared to biopsy, with a mean interval of 18 months between the initial cancer diagnosis and prostatectomy. This prevalence of grade change is less than in our population that underwent prostatectomy within 1 to 3 months after biopsy. Conclusions: Because most grade changes occurred relatively soon after biopsy, it implies that tumor grade did not evolve but rather the higher grade component was not initially sampled. During a 1 1/2 to 2-year period after biopsy there is no evidence that prostate cancer grade worsens significantly. Men with prostate cancer need not feel concerned about waiting several months before undergoing surgery after biopsy. Furthermore, men undergoing watchful waiting can be reassured that there is little evidence that prostate cancer grade worsens during the short term.