[Brachytherapy for anal cancers]

Abstract

Low dose-rate brachytherapy as a boost after concomitant chemoradiation therapy is a standard of care for locally advanced anal carcinoma, providing a rigorous selection taking into account the initial staging and tumor response to external beam radiotherapy. Local control is likely to be superior when the boost is performed with brachytherapy than with external beam radiotherapy. The several steps of the brachytherapy procedure are described. The standard treatment scheme is a concomitant chemoradiation therapy, including 45 Gy (1,8 Gy × 5) pelvic external beam radiotherapy and two courses of 5-fluorouracil and mitomycin-C, followed by a 15 Gy brachytherapy boost with a gap limited to 2 to 3 weeks. Higher irradiation dose for the most advanced cases has not yet demonstrated a therapeutic gain in terms of colostomy free survival. Exclusive brachytherapy for in-situ carcinoma or invasive carcinoma less than 10mm is not recommended due to a high risk of local recurrence. Pulsed dose rate brachytherapy is an alternative to low dose rate brachytherapy (iridium wires) providing the respect of the recommended dose rate (0.5 to 1 Gy/hour). High dose rate brachytherapy is still under evaluation.