HDR boost (real time) in patients with localized prostate cancer: technical description and preliminary results
Spira G¹, Weise C¹, Neubauer S², Blumberg J¹, Ernst C¹, Mühlnickel W¹, Derakhshani P²

Department of Radiation Oncology, Klinik am Ring, Cologne 1
Department of Urology, Klinik am Ring, Cologne 2

It has been well documented that the outcome of prostate cancer treatment depends on the dose administered. Hence, techniques have been developed that allow high-dose administration without increasing the complications, e.g. external radiotherapy combined with high-dose radiation (HDR) boost. In this study we analyse the technique and protocol of real-time HDR boost together with clinical results and quality of dosimetric parameters that support its use.

Between June 2003 and December 2007, 416 patients with prostate cancer were treated with 50.4 Gy of external irradiation to the pelvis (single fraction 1.8 Gy) and 3 HDR brachytherapy fractions (each 7.5Gy) at the end of a 5-week radiotherapy course. All brachytherapy implants were planned using the Nucletron SWIFT realtime ultrasound based planning system. The 1997 American Joint Commission on Cancer (AJCC) system was used to establish disease stage. Patients with low-risk (7.8%), intermediate-risk (40.1%) and high-risk (52.1%) without metastases were eligible for the brachytherapy. 53% of Patients received neoadjuvant or adjuvant androgen deprivation therapy. Biochemical failure was defined according to the American Society for Therapeutic Radiology and Oncology (ASTRO) consensus panel statement. Toxicity was scored according to RTOG guidelines.

The mean age of patients was 67.5 years (range 50.5-86). Median follow-up was 31 months (range: 12-56). Median PSA decreased from initially 11 ng/ml to 0.15 ng/ml after 36 months. No grade 4 complications were noted. Mean V100 prostate in all patients was 94.8% (range 74-99.8), mean D90 prostate was 7.97 Gy (range 5.3-9.8), median D10 urethra was 8.56 Gy (range 6.9-11.2) and median D10 rectum was 4.5 Gy (range 2.0-7.4). Patients were stratified for prostate volume. In the 76 patients with prostate volumes above 40 cc there was no major difference in dosimetric quality as compared to small prostates (D90 Prostate 7.96 vs. 7.97, V100 93.6 vs. 95.1, D10 Urethra 8.58 vs. 8.55, D10 Rectum 4.96 vs. 4.36).