Novel prostate brachytherapy technique: Improved dosimetric and clinical outcome

• Published in: Radiotherapy and oncology Vol. 88; no. 1; pp. 121 - 126
• Main Authors: Nobes, Jenny P, Khaksar, Sara J, Hawkins, Maria A, Cunningham, Melanie J, Langley, Stephen E.M, Laing, Robert W
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 01.07.2008
• Subjects: Brachytherapy - adverse effects; Brachytherapy - methods; Erectile dysfunction; Erectile Dysfunction - etiology; Hematology, Oncology and Palliative Medicine; Humans; Implant technique; Iodine Radioisotopes - therapeutic use; Male; Middle Aged; Penile bulb; Penis - radiation effects; Prostate brachytherapy; Prostatic Neoplasms - radiotherapy; Radiotherapy Dosage; Statistics, Nonparametric; Treatment Outcome; Ultrasonography, Interventional; Penile bulb; Implant technique; Erectile dysfunction; Prostate brachytherapy
• ISSN: 0167-8140; 1879-0887
• DOI: 10.1016/j.radonc.2008.04.012

Abstract Purpose Erectile dysfunction following prostate brachytherapy is reported to be related to dose received by the penile bulb. To minimise this, whilst preserving prostate dosimetry, we have developed a technique for I-125 seed brachytherapy using both stranded seeds and loose seeds delivered with a Mick applicator, and implanted via the sagittal plane on trans-rectal ultrasound. Materials and methods Post-implant dosimetry and potency rates were compared in 120 potent patients. In Group 1, 60 patients were treated using a conventional technique of seeds implanted in a modified-uniform distribution. From January 2005, a novel technique was developed using stranded seeds peripherally and centrally distributed loose seeds implanted via a Mick applicator (Group 2). The latter technique allows greater flexibility when implanting the seeds at the apex. Each patient was prescribed a minimum peripheral dose of 145 Gy. No patients received external beam radiotherapy or hormone treatment. There was no significant difference in age or pre-implant potency score (mean IIEF-5 score 22.4 vs. 22.6, p = 0.074) between the two groups. Results The new technique delivers lower penile bulb doses ( D25 as %mPD – Group 1: 61.2 ± 35.7, Group 2: 29.7 ± 16.0, p < 0.0001; D50 as %mPD – Group 1: 45.8 ± 26.9, Group 2: 21.4 ± 11.7, p < 0.0001) whilst improving prostate dosimetry ( D90 – Group 1: 147 Gy ± 21.1, Group 2: 155 Gy ± 16.7, p = 0.03). At 2 years, the potency rate was also improved: Group 1: 61.7%; Group 2: 83.3% ( p = 0.008). Conclusions In this study, the novel brachytherapy technique using both peripheral stranded seeds and central loose seeds delivered via a Mick applicator results in a lower penile bulb dose whilst improving prostate dosimetry, and may achieve higher potency rates.