[Bladder cancer radiotherapy margins].

Radical cystectomy is the gold standard treatment of invasive bladder carcinoma, but conservative treatment is a serious option for selected patients. It comprises a transurethral resection, as complete as possible, before a radiation therapy of the whole bladder and pelvis, with a concomitant chemotherapy. Bladder wall movements during the treatment course lead to the use of wide margins to cover the clinical target volume. Planning target volume margins must be anisotropic to correspond to the mobility of each bladder zone: 10mm in the inferior portion, 15 mm in lateral directions, and 20 to 25 mm in anterior and superior directions. The development of image-guided radiotherapy and adaptative radiotherapy should lead to a reduction of these margins. Besides, partial bladder radiotherapy is showing encouraging results, by reducing the clinical target volume in well-selected patients.