Purpose: To describe the technique and early results of ultrasound (US)-guided interstitial prostate brachytherapy (BT) introduced at our institute.
Materials and methods: Between December 2001 and July 2002, ten patients with clinically localised, high risk prostate cancer were treated with external beam irradiation and high dose rate (HDR) BT boost at the Radiotherapy Department of National Institute of Oncology, Budapest. Using CT based treatment planning, 46 Gy was delivered to the whole pelvis and then the prostate and vesicles were treated up to a total dose of 60 Gy by conformal external beams. BT boost was given in the first four weeks of external irradiation. Nine patients were under total androgen blockade. The interstitial BT was performed in spinal anaesthesia. Steel needles were implanted into the prostate using transrectal US guidance. The Ir-192 HDR isotope was loaded into the needles by remote control after-loading equipment. Treatment planning was based on transversal ultrasound images. The target volume was the whole prostate. The median number of inserted needles was 9 (range: 5-13). The prescribed dose to the surface of the prostate was 8 or 10 Gy, and the maximum reference dose of the urethra or rectum was less than 125% and 80% of the prescribed dose, respectively. PSA (prostate specific antigen) levels and acute side effects were monitored and documented regularly.
Results: The prescribed treatment was completed on all patients. The median follow-up time from the completion of the radiotherapy was 6 months (range: 2-11 months). Perioperative side effects (haematuria caused by puncture of the bladder) occurred in two cases. Acute grade 2 toxicity was observed in four patients: genitourinal inflammation in 4, and proctitis in 2 cases. No PSA relapse occurred so far.
Conclusion: In our study we described our technique of interstitial BT boost as a part of prostate radiotherapy used for the first time in Hungary. The US based treatment planning resulted in adequate dose distribution in all cases. Incidence of perioperative and acute side effects were comparable to data known from the literature. Appropriate technical background and well organised team work are needed to ensure the good quality of the treatment.