21 Urinary Bladder Cancer

Urinary Bladder Cancer

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THE GEC ESTRO HANDBOOK OF BRACHYTHERAPY | Part II: Clinical Practice Version 1 - 21/04/2015

ual suprapubic and transrectal palpation during anaesthesia for cystoscopy. Ultrasonography, CT or MRI may be helpful in as- sessing the depth of invasion. CT often underestimates the depth of tumour extension into the bladder wall (12). With MR, bet- ter distinction between the bladder wall layers and invasion in neighbouring organs can be appreciated, which can help in bet- ter tumour staging (13). If possible, a complete transurethral re- section of the tumour is performed (TUR), and random biopsies are taken of the remaining bladder mucosa. An accurate draw- ing of the tumour and its relation to the ureteral ostia should be made. The pathologist should carefully assess grade and depth of invasion. For the primary work up blood chemistry, and a CT scan of the whole abdomen and thorax are necessary. For assessment of lo- cal extent and of abdominal pathology, an MRI scan may also be recommended. To complete the investigation of the upper urinary tract, an excretory-phase CT urography is done. A bone- scan and CT-brain are only indicated in case of suspicious symp- toms. Currently there is no convincing evidence for routine use of PET-scan in the primary diagnostic work up. The multidisciplinary committee should take the final therapeu- tic decision. The indication for brachytherapy of bladder cancer is a solitary tumour of maximal 5 cm in diameter. The most common stage is pT2 after transurethral resection of the bladder (TURB). pT1 tumours can also be treated with brachytherapy, but these tu- mours are nowadays usually treated by TURB with or without bladder instillations. Limited pT3 tumours can also be implant- ed provided that there is enough dose coverage at the periphery of the tumour. Implantations of pT3 tumours should be reserved for brachytherapists with considerable experience. Multifocality is considered as not suitable for brachytherapy, although small multifocal papillary tumours within a limited area of less than 3-5 cm have been implanted with success (14). Tumours located in the bladder neck are difficult to implant by the open suprapubic approach and this is therefore considered as a relative contraindication. In this area, access to the bladder wall is hampered by the pubic bone. However, this area can more easily be implanted with the robotic technique. 6. INDICATIONS AND CONTRAINDICATIONS

Fig 22.2: Tweezers pointing at TURB scar area at cystotomy.

Fig 22.3: TURB scar area with 5 mm margin for CTV.

8. TECHNIQUES

Brachytherapy for bladder cancer is performed by an afterload- ing technique. Extensive experience has been gained with con- tinuous low-dose rate (cLDR) with Caesium needles and Iridium wires (15-21). Nowadays cLDR has been replaced by pulsed- dose rate (14, 22, 23) or HDR stepping source afterloaders. For brachytherapy for bladder cancer flexible catheters are placed within the bladder wall. There are two techniques to place the catheters. The original technique is by performing a cystostomy to insert the catheters, the so-called suprapubic approach. The second technique is with laparoscopy and/or robot-assistance. In the latter case the bladder is not opened. The catheters used are either double-leader catheters or specially designed catheters for laparoscopic use. When performing the suprapubic approach, a median suprapubic or Pfannenstiel incision is performed. For the laparoscopic techniques, four 1 cm incisions are used for the insertion of instruments. Catheters are placed at the position of a visible tumour or TURB scar tissue (Fig 22.2). If a partial cystectomy has been performed, two catheters are placed at either side of the bladder slice plane. All the techniques have in common that the catheters will exit through the abdominal wall.

7. TARGET VOLUME

The clinical target volume (CTV) for brachytherapy includes the gross disease (GTV) or the bladder scar after TURB (Fig. 22.2) or partial cystectomy cutting edge, and a circular security mar- gin of 5 mm (Fig 22.3). The full thickness of the bladder wall should be in the CTV with mucosa, submucosa and muscle lay- ers. The localisation and size of the CTV is indicated by direct visualisation either with cystotomy or cystoscopy and measured by the circular calliper. Because the catheters are located within the bladder wall no PTV margin is used, although no studies have been done up till now to investigate the positional accuracy.