A Multi-Institution Comparison of SBRT and IMRT for Definitive Re-Irradiation of Recurrent or Second Primary Head and Neck Cancer
Menée à partir de données portant sur 414 patients ayant été traités une seconde fois par rayonnements ionisants pour un carcinome épidermoïde de la tête et du cou non réséqué, cette étude multicentrique compare l'efficacité, du point de vue de l'échec locorégional et de la survie globale, et la sécurité d'une radiothérapie corporelle stéréotaxique et d'une radiothérapie avec modulation d'intensité
Purpose : Two modern methods of re-irradiation, IMRT and SBRT, are established for patients with recurrent or second-primary squamous carcinoma of the head and neck (rSCCHN). We performed a retrospective multi-institution analysis to compare methods. Material/Methods : Patients with unresected rSCCHN previously-irradiated to ≥40 Gy who underwent re-irradiation with IMRT or SBRT were collected from eight institutions. First, the prognostic value of our IMRT-based recursive partitioning analysis (RPA) separating those unresected patients with intertreatment interval >2 years or those with ≤2 years and without feeding tube or tracheostomy dependence (Class II) from other unresected patients (Class III) was investigated among SBRT patients. Overall survival (OS) and locoregional failure (LRF) were then compared between IMRT and SBRT using two methods to control for baseline differences: Cox regression weighted by the inverse probability of treatment and subset analysis by RPA classification. Results : 414 patients with unresected rSCCHN were included: IMRT-217, SBRT-197. Unadjusted 2-year OS was 35.4% for IMRT and 16.3% for SBRT (p<0.01). Among SBRT patients, RPA classification retained independent association with OS. On Cox regression weighted by the inverse probability of treatment, no significant differences in OS or LRF between IMRT and SBRT were demonstrated. Analysis by RPA class demonstrated similar OS between IMRT and SBRT for class III patients. In all class II patients, IMRT was associated with improved OS (p<0.001). Further subset analysis demonstrated comparable OS when ≥35 Gy was delivered with SBRT to small tumor volumes. Acute grade ≥4 toxicity was greater in the IMRT compared to the SBRT group (5.1% vs. 0.5%, p<0.01), with no significant difference in late toxicity. Conclusion : Re-irradiation with both SBRT and IMRT appear relatively safe with favorable toxicity compared to historic studies. Outcomes vary by RPA class, which informs clinical trial design. Survival is poor in class III patients and alternative strategies are needed.