Long-Term Results of Retropubic Permanent 125 Iodine Implantation of the Prostate for Clinically Localized Prostatic Cancer

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Abstract
The historical series of retropubic prostate radioactive source implantation from the Memorial Sloan-Kettering Cancer Center has served as the framework for the current transperineal implant approaches used in the treatment of localized prostatic cancer. We report the final assessment of the 15-year outcome. Between March 1970 and December 1987, 1,078 patients with biopsy proved adenocarcinoma of the prostate were treated at our cancer center with permanent implantation of125 iodine via a retropubic approach. In addition, all patients underwent bilateral pelvic lymphadenectomy before implantation. The clinical stages of disease were B1 in 234 patients (22%), B2 in 472 (44%), B3 in 145 (14%) and C in 227 (20%). Of the patients 733 (68%) had pathologically negative lymph nodes, whereas 345 (32%) had positive lymph nodes at lymph node dissection. Median followup was 11 years. Multivariate analysis identified nodal involvement, high grade disease, clinical stage B3/C and implant doses less than 140 Gy. as independent predictors of local relapse. Independent predictors of distant metastases included nodal involvement, stage B3/C disease and poorly differentiated histological status. The local recurrence-free survival rates for patients with negative nodes at 5, 10 and 15 years were 69, 44 and 24%, respectively. The distant metastases-free survival rates at 5, 10 and 15 years for patients with negative lymph nodes were 59, 36 and 21%, respectively. (125) Iodine implantation of the prostate via the retropubic approach was associated with a greater than expected incidence of local relapse at 15 years. Technical limitations of the retropubic technique resulting in suboptimal distribution of the isotope within the prostate are believed to be the explanation for the inferior local control outcome. Although long-term results are not yet available, the 5-year results of the computer optimized transperineal prostate implantation suggest that improved implant techniques will translate into a greater likelihood of tumor control.