3-D conformal HDR brachytherapy as monotherapy for localized prostate cancer. A pilot study

Abstract

Purpose: Pilot study to evaluate feasibility, acute toxicity and conformal quality of three-dimensional (3-D) conformal high-dose- rate (HDR) brachytherapy as monotherapy for localized prostate cancer using intraoperative real-time planning.

Patients and methods: Between 05/2002 and 05/2003, 52 patients with prostate cancer, prostate-specific antigen (PSA) < or = 10 ng/ml, Gleason score < or = 7 and clinical stage < or = T2a were treated. Median PSA was 6.4 ng/ml and median Gleason score 5. 24/52 patients had stage T1c and 28/52 stage T2a. For transrectal ultrasound-(TRUS-)guided transperineal implantation of flexible plastic needles into the prostate, the real-time HDR planning system SWIFT((R)) was used. After implantation, CT-based 3-D postplanning was performed. All patients received one implant for four fractions of HDR brachytherapy in 48 h using a reference dose (D(ref)) of 9.5 Gy to a total dose of 38.0 Gy. Dose-volume histograms (DVHs) were analyzed to evaluate the conformal quality of each implant using D(90), D(10) urethra, and D(10) rectum. Acute toxicity was evaluated using the CTC (Common Toxicity Criteria) scales.

Results: Median D(90) was 106% of D(ref) (range: 93-115%), median D(10) urethra 159% of D(ref) (range: 127-192%), and median D(10) rectum 55% of D(ref) (range: 35-68%). Median follow-up is currently 8 months. In 2/52 patients acute grade 3 genitourinary toxicity was observed. No gastrointestinal toxicity > grade 1 occurred.

Conclusion: 3-D conformal HDR brachytherapy as monotherapy using intraoperative real-time planning is a feasible and highly conformal treatment for localized prostate cancer associated with minimal acute toxicity. Longer follow-up is needed to evaluate late toxicity and biochemical control.