Changes in cell proliferation and apoptosis during local progression of prostate cancer.

To determine the changes in biological features of the prostate during the course of local recurrence of prostate cancer after endocrine therapy, histologic grade, proliferating activity and apoptotic indices were examined in prostate specimens obtained before treatment and at recurrence. A total of 16 patients, who had received endocrine therapy and eventually recurred in the prostate, were evaluated. Histologic grade was determined by the method of Gleason and the number of proliferating cells and apoptotic cells were counted. Tumors with a high grade Gleason score remained at a high grade. A statistically significant increase in the number of Ki-67 positive cells was observed from pretreatment biopsy to local recurrence. On the other hand, the apoptotic index decreased during progression. Patients with a higher number of Ki-67 positive cells before the initial treatment had a poorer prognosis than those with a lower number of Ki-67 positive cells. In conclusion, prostate cancer shows an increase of malignant potential as assessed by the number of Ki-67 positive cells, whilst the decrease in apoptosis might play some role in the course of progression.