High-dose-rate brachytherapy: Indications, technique, and results

High-dose-rate (HDR) brachytherapy is an established curative treatment option for patients diagnosed with prostate cancer. In contrast to low-dose-rate (LDR) brachytherapy, that involves the permanent implant of several radioactive seeds in the prostate, HDR uses a single, high-intensity radioactive source of 192Iridium which is sent and retracted sequentially into each of the needles (or catheters) temporarily implanted in the gland. Advances in mechanical and planning systems and in computer technology result in a sophisticated treatment technique that reliably delivers a very high-quality radiation dose distribution to the target in a very short period of time while minimizing the irradiation of the surrounding critical organs. Several advantages over other radiotherapy techniques have been identified, namely, (1) the accurate positioning of the sources by first implanting nonactive guide needles, (2) the possibility to exactly choose the position of the source over the entire length of every single needle, (3) the absence of any target movement during irradiation, (4) the possibility of online adjustments of dwell source locations according to 3-D planning based on individual dose prescription, (5) the absence of any need for preimplant needles preparation, and finally (6) a safer radioprotection profile as compared to permanent seeds implant procedure. HDR brachytherapy is generally proposed in combination with external beam irradiation for patients having intermediate- to high-risk cancers, but protocols have been recently developed in order to use it as monotherapy for low-risk cases. In this chapter, the rational, indications, technique, and clinical results (both in terms of efficacy and toxicity) of HDR brachytherapy for prostate cancer will be presented and discussed. Finally, some future directions together with critical issues regarding this technique will be addressed.