23. Anal Cancer - The GEC-ESTRO Handbook of Brachytherapy

Anal Cancer

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THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 01/03/2023

should be the standard of care. - T4 tumours (except for T4 tumours extending into the anovaginal septum) should not be considered for brachytherapy - Tumour length: the maximal longitudinal length should be not more than 5cm Advanced age is not a contraindication for brachytherapy, as comparable tumour control and similar toxicity level with younger patients have been reported for the elderly [32,33].

(the initial macroscopic gross tumour volume), using all available initial multimodal imaging (CT-scan, MRI, PET-scan), with safety margins of 5mm in all directions. The organs at risk (OARs) are the healthy anal and rectal mucosa and the anal sphincter. At time of brachytherapy, it may be difficult to distinguish between the healthy tissues and the initial tumoral area due to the tumoral volume shrinkage. A complete tumoral response is present in two-thirds of cases at time of brachytherapy. A careful and rigorous initial clinical examination, ideally performed by the brachytherapist, is therefore essential to perfectly define the limits between CTV and OARs. If the initial clinical examination is done under general anaesthesia, it is also advisable to place metal clips at the proximal and distal end and on both lateral sides of the gross disease. Also, when the tumour extends to the anal margin, it may be useful to tattoo the skin around the tumour before treatment, as a future reference for the delineation of the CTV. Careful delineation of the boost target area reduces complication risks for anal stenosis or necrosis by limiting the high dose area to what is strictly needed.

7. TUMOUR AND TARGET VOLUMES

Targets volume for the initial EBRT involve the primary tumour area and any sites of likely nodal involvement. The usual lymph node areas retained in the prophylactic target volumes are all bilateral pelvic and inguinal lymph nodes, but there are significant differences in approach within Europe. For the IBT boost, the clinical target volume (CTV) is defined as the initial, before any treatment, palpable and visible tumour

Figure 6 - Implantation procedure - a.: equidistant and parallel needles within the horseshoe-shaped Papillon’s template - b. : implantation of the needles under digital control - c. : applicator in place - d. : the anal dilatator and the implant, sutured to the perineum