Volume, Dose, and Fractionation Considerations for IMRT-based Re-Irradiation in Head and Neck Cancer : A Multi-Institution Analysis
Menée à partir de données portant sur 505 patients atteints d'un carcinome épidermoïde récidivant ou d'un second carcinome de la tête et du cou, cette étude multicentrique évalue, en fonction du volume tumoral, de la dose de rayonnements administrée et du degré de fractionnement, l'effet d'une seconde irradiation par radiothérapie avec modulation d'intensité sur le contrôle locorégional de la maladie et la survie globale, puis analyse la toxicité du traitement
Purpose : Limited data exists to guide treatment technique for re-irradiation of recurrent or second primary (RSP) squamous carcinoma of the head and neck. We performed a multi-institution retrospective cohort study to investigate the impact of elective treatment volume, dose, and fractionation on outcomes and toxicity. Patients and Methods : Patients with RSP squamous carcinoma originating in a previously-irradiated field (≥40 Gy) who underwent re-irradiation with IMRT (≥40 Gy re-IMRT) were included. Impact of elective nodal treatment, dose and fractionation on overall survival (OS), locoregional control (LRC), acute and late toxicity were assessed. Kaplan-Meier and Gray’s competing risks methods were used for actuarial endpoints. Results : From eight institutions, 505 patients were included in this updated analysis. The elective neck was not treated in 56.4% of patients. The median dose of re-IMRT was 60 Gy (39.6–79.2 Gy). Hyperfractionation was used in 20.2%. Systemic therapy was integrated for 77.4% of patients. Elective nodal radiotherapy did not appear to decrease the risk of LRF or improve the rate of OS. Doses ≥66 Gy were associated with both improvements in LRF as well as OS in the definitive re-IMRT setting, whereas dose did not obviously impact LRF or OS in the post-operative re-IMRT setting. Hyperfractionation was not associated with improved LRF or OS. The rate of acute grade ≥3 toxicity was 22.1% overall. On multivariate logistic regression, elective neck irradiation was associated with increased acute toxicity in the postoperative setting. The rate of overall late grade ≥3 toxicity was 16.7%, with patients treated postoperatively with hyperfractionation experiencing the highest rates. Conclusion : Doses ≥66 Gy may be associated with improved outcomes in high-performance patients undergoing definitive re-IMRT. Postoperatively, doses of 50-66 Gy appear adequate after removal of gross disease. Hyperfractionation and elective neck irradiation are not associated with an obvious benefit and may increase toxicity.