Comparison of stereotactic body radiation therapy to radiofrequency ablation in the treatment of intrahepatic metastases
Menée sur 161 patients présentant au total 282 métastases hépatiques non résécables (durée médiane de suivi : 24,6 mois), cette étude compare l'efficacité, du point de vue de l'absence de progression locale, et la tolérabilité d'une radiothérapie corporelle stéréotaxique et d'une ablation par radiofréquence en fonction de la taille des métastases (inférieure à 2 cm, supérieure ou égale à 2 cm)
Purpose : Stereotactic body radiation therapy (SBRT) and radiofrequency ablation (RFA) are widely used therapies for the treatment of intrahepatic metastases; however, direct comparisons are lacking. We sought to compare outcomes for these two modalities. Methods and Materials : From 2000-2015, 161 patients with 282 pathologically diagnosed unresectable liver metastases were treated with RFA (n=112) or SBRT (n=170) at a single institution. The primary outcome was freedom from local progression (FFLP). The effect of treatment and covariates on FFLP was modeled using a mixed-effects Cox-model with application of inverse probability treatment weighting to adjust for potential imbalances in treatment modality. Results : Median follow-up was 24.6 months. Patients receiving SBRT had larger tumors than those treated with RFA (median 2.7 vs. 1.8 cm, p<0.01). On univariate analysis, tumor size was associated with worse FFLP for RFA (HR:1.57, 95%CI:1.15-2.14, p<0.01), but not SBRT (HR:1.38, 95%CI:0.76-2.51, p=0.3). 2-year FFLP was 88.2% compared to 73.9%, favoring SBRT (p=0.06). For tumors ≥2 cm in diameter, SBRT was associated with improved FFLP (HR:0.28, 95%CI:0.09-0.93, p<0.01). On multivariate analysis, treatment with SBRT (HR:0.21, 95%CI:0.07-0.62, p=0.005) and smaller tumor size (HR:0.65, 95% CI:0.47-0.91, p=0.01) were associated with improved FFLP. 2-year OS was 51.1% with no difference between groups (p=0.8). Grade 3+ treatment related toxicity was rare with no difference between SBRT (n=4) and RFA (n=3). Conclusions : Treatment with SBRT or RFA is well tolerated and provides excellent and similar local control for intrahepatic metastases <2 cm in size. For tumors ≥2 cm in size, treatment with SBRT is associated with improved FFLP and may be the preferable treatment.