22 Penis Cancer

482 Penis Cancer

consequently better determination of the target volume; secondly to decrease side effects of brachytherapy or external beam radiotherapy. (10) The target volume must also be defined taking into account the different tumour types (see Fig 21.2): − superficial tumours : thickness, peripheral limits, − exophytic tumours : accurate knowledge of the tumour and its basis (depth of implantation), − infiltrating (± ulcerating) tumours : exact topography of the infiltration, depth of the ulceration. The anatomical position of the penile urethra should be marked with a Foley catheter. (12) Some authors consider it is necessary to include the whole glans in the target volume; we prefer a selected PTV, which is possible with a well adapted technique and a good knowledge of the GTV. 7.1 Plesiobrachytherapy Plesiobrachytherapy is indicated for very superficial lesions (no more than 5mm thick) with well defined limits. (1,24) Essentially two types of surface applicators can be used: a personalized one, made for each patient, or a standard one, less individualised but perhaps easier to use. The first consists of a mould containing catheters placed according to the tumour topography afterloaded with an iridium source for HDR (Fig 21.3) or LDR brachytherapy. When LDR brachytherapy is applied, the mould must be fixed to the surface of the penis, because of the risk of displacement during irradiation. 7 Technique

Fig 21.3: Personalized plastic applicator (courtesy of JC Horiot and S Naudy)

The second is more often used; it is made of two plastic cylinders, the inner one worn over the penis, the outer one containing iridium sources. This kind of LDR brachytherapy requires close compliance from the patient, who usually has to place the applicator around the penis himself and also record the exact duration of each treatment.