Long term outcomes of phase I and II studies of SBRT for hepatic colorectal metastases
Menée à partir de données portant sur 60 patients présentant des métastases hépatiques d'origine colorectale et inclus dans des essais de phase I ou II conduits entre 2003 et 2012 (durée médiane de suivi : 28,1 mois), cette étude évalue l'efficacité, du point de vue du contrôle local de la maladie, et la toxicité d'une radiothérapie stéréotaxique corporelle ciblant les métastases, puis identifie les facteurs clinico-pathologiques associés à la survie
Background and purpose : To report mature outcomes of prospective phase I/ II studies of stereotactic body radiotherapy (SBRT) for treatment of colorectal liver metastases (CLM). Materials and methods : Patients with histologically confirmed CLM unsuitable for resection or standard therapies were eligible for sequential phase I and II studies conducted from 2003-2012. Results : Of sixty patients treated, 82% had received previous chemotherapy, 23% previous focal liver treatment and 38% had extrahepatic disease at time of SBRT. The median number of gross tumor volume (GTV) targets per patient was 1 (range 1-6) with median total target volume of 117.7 cm3 (6.7-3115.4 cm3). The median minimum dose to GTV was 37.6 Gy (range 22.7 – 62.1 Gy) in six fractions over two weeks. Other than one G3 nausea, there was no > G2 acute toxicity. With a median follow-up for survivors of 28.1 months, no GI bleed, biliary or liver toxicity was seen. Local control per lesion at one and four years was 49.8% and 26.2%. Increasing GTVmin dose was associated with improved local control (p = 0.003). Median overall survival was 16.0 months (95% CI 11.9 – 20.5 months). On multivariate analysis, improved survival was associated with smaller total GTV volume (p=0.017), performance status 0-1 (p=0.007), no extra-hepatic disease at time of treatment (p=0.005) and local control of targeted liver disease (p=0.001). Two long term survivors remain disease free at 49 and 125 months respectively. Conclusions : Six fraction SBRT for CLM is safe and may be associated with long term cure. Local control was significantly associated with delivered dose, and is lower than seen in other studies using a higher SBRT dose. Survival was associated with smaller tumor volume, absence of extra-hepatic disease, performance status 0-1 and local control of treated liver lesions.