High dose rate brachytherapy for prostate cancer.
High dose rate (HDR) afterloading brachytherapy in the management of localised prostate cancer has practical, physical and biological advantages over low dose rate seed brachytherapy. There are no free live sources used, no risk of source loss and since the implant is a temporary procedure following discharge no issues with regard to radioprotection use of existing facilities. Adequate coverage of extracapsular and seminal vesicle tumour is possible for advanced cases and HDR brachytherapy is the most efficient means of obtaining dose escalation in terms of biological dose based on a low alpha/beta ratio. Selection for HDR brachytherapy includes patients with any prostate specific antigen (PSA) level provided there is no demonstrable metastasis, any Gleason score and stages T1B to T3B. The results of a randomised trial show that HDR brachytherapy is an effective means of dose escalation with a favourable therapeutic ratio when compared with standard external beam radiotherapy. Current studies are evaluating HDR brachytherapy as monotherapy delivering a radical dose in two to four fractions. The acute toxicity with HDR brachytherapy is short-lived and far less severe than seen with low dose rate brachytherapy and late toxicity rates are low.
Hoskin
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Mount Vernon Cancer Centre, Rickmansworth Road, Northwood, HA6 2RN Middlesex, United Kingdom. peterhoskin@nhs.net