Biochemical disease-free survival following 125I prostate implantation.

PURPOSE

To assess the 5-year clinical and biochemical results of ultrasound-guided permanent 125I brachytherapy in early adenocarcinoma of the prostate. Biochemical disease-free survival (BDFS) is reported, using PSA follow-up and is compared to the surgical and radiation therapy literature.

METHODS AND MATERIALS

From December 1988 through December 1993, ultrasound-guided brachytherapy was preplanned with 125I and delivered 160 Gy as the sole treatment in 499 patients. All were clinically staged as T1 or T2 node-negative adenocarcinoma of the prostate. Within the first year, 10 patients were lost to follow-up and have been excluded from further study. The remaining 489 patients form the basis of this report. Clinical status and prostate specific antigen (PSA) values were systematically recorded before and after treatment.

RESULTS

With a median follow-up of 35 months (3-70), the actuarial clinical local control is 83%. Both stage and grade are shown to predict for this endpoint. Actuarial biochemical disease-free survival (BDFS) is also correlated with stage, grade, and PSA at presentation. Biochemical disease-free survival at 5 years is 94% for T1, 70% for unilateral T2, and 34% for T2c tumors. Grade is also predictive, ranging from 85% in low-grade tumors to 30% in high-grade tumors. In a multivariate analysis, the pretreatment PSA is most highly correlated (p < 0.0001) with BDFS, local control, and clinical disease-free survival. Patients with a normal pretreatment PSA enjoyed 93% BDFS, while those presenting with PSA > 10 had a BDFS of 40%. Complications have been few, with severe urinary urgency or dysuria in 4% and both incontinence and proctitis seen in 1%.

CONCLUSIONS

While biochemical disease-free survival reports in the literature are immature and have short follow-up, our data compares favorably with studies following radical prostatectomy or radiation therapy. Further follow-up of this cohort is required. The complication rate is low and patient acceptance excellent. Permanent implantation of 125I as the sole treatment for early prostate adenocarcinoma is a viable alternative for patients with early-stage and low- to moderate-grade cancers. The PSA provides significant prognostic information and aids in case selection. Better management options are needed for high grade and bilateral tumors.