LOCALLY RECURRENT PROSTATE TUMORS FOLLOWING EITHER RADIATION-THERAPY OR RADICAL PROSTATECTOMY HAVE CHANGES IN KI-67 LABELING INDEX, P53 ANDBCL-2 IMMUNOREACTIVITY

Purpose: We compare the biological phenotype of recurrent prostatic tu mors after definitive local therapy (radiation or radical prostatectom y) with that of the same tumors before treatment. Materials and Method s: Cellular proliferation (Ki-67 labeling index), p53 nuclear reactivi ty and bcl-2 immunoreactivity were determined in pretreatment and post treatment tumor specimens from 13 patients with local tumor recurrence following radiation, and in 18 patients with local tumor recurrence f ollowing radical prostatectomy. Results: Mean Ki-67 labeling index inc reased approximately 2-fold in locally recurrent tumors after radiatio n (10.5 versus 5.6%, p = 0.0008) or surgery (6.0 versus 3.2%, p = 0.00 25) when compared with pretreatment tumors. We noted p53 nuclear react ivity in a significantly higher proportion of recurrences than in pret reatment tumors following radiation (54 versus 8%, p = 0.032) and surg ery (39 versus 5%, p = 0.022). Although bcl-2 immunoreactivity was als o seen in a higher proportion of recurrent tumors, this difference did not reach statistical significance for either radiation or surgery. C onclusions: Recurrent tumors following either radiation or surgery dif fer significantly from the corresponding pretreatment tumors with resp ect to cellular proliferation and p53 nuclear reactivity.