Clinical stage T3 prostate cancer: the added value of three-dimensional conformal/intensity-modulated external-beam radiotherapy.

摘要

The breakthrough represented by androgen deprivation (AD) combined with irradiation for locally advanced prostate cancer was obtained with conventional techniques, now abandoned in favor of three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT), which improve local control by means of dose escalation without increasing the risk of morbidity. Both techniques take into account the anatomic data acquired by scanning patients in the treatment position, transferred to the three-dimensional treatment planning system where the clinical target volume is drawn, and then surrounded by a safety margin; at the time of irradiation, a multileaf collimator adapts automatically and continually to the contours of the target volume seen by each beam. IMRT requires a specific software because the movement of the leaves during the course of the irradiation allows the adaptation of the dose to be delivered within the treatment field and provides concave isodose curves. Zelefsky et al , from the Memorial Sloan-Kettering Cancer Center (New York, NY, USA), reported a retrospective analysis with 3D-CRT used for 296 patients suffering from locally advanced prostate cancer; 130 had cT3a NO-X MO disease and 166 had cT3b NO-X MO disease according to the 1997 American Joint Committee on Cancer (AJCC) classification. The prescribed doses to the prostate ranged from 66 Gy to 86.4 Gy; 95 patients received IMRT with dose escalation beyond 81 Gy.