ANALYSIS OF BIOPSY FINDINGS AND IMPLANT QUALITY FOLLOWING ULTRASONICALLY-GUIDED I-125 IMPLANTATION FOR LOCALIZED PROSTATIC-CARCINOMA

Transperineal ultrasound-guided I-125 implantation was undertaken in 5 2 patients with localised prostate cancer. After implantation, ultraso und-guided biopsies were taken from the previous malignant areas every 6 months in all patients. The percentage of negative biopsies increas ed from 22% at 6 months to 50% at 48 months. Implant quality was analy sed in 37 patients. The difference between isodose levels encompassing the prostate and the aimed levels of 160 Gy was taken as a measure of implant quality. A good quality implant (< 10% underdosage) was found in 43% of patients, a moderate quality (10-25% underdosage) in 35%, a nd a poor quality implant (> 25% underdosage) in 22%. A statistically significant correlation was found between the quality of the implant a nd resulting negative biopsy at the original tumour site. Determinatio n of prostate specific antigen (PSA) was not possible from the beginni ng of the study but an analysis with biopsy findings, implant quality and prostate volume reduction during follow-up has been performed sinc e 1989. A significant correlation was observed between implant quality and serum PSA, and also between volume reduction and serum PSA.