Re-evaluation of Ipsilateral Radiation for T1-T2N0-N2b Tonsil Carcinoma at the Princess Margaret Hospital in the HPV Era, 25 Years Later
Menée à partir de données portant sur 427 patients atteints d'un carcinome de l'amygdale de stade T1-T2N0-N2b traité entre 1999 et 2014 (durée médiane de suivi : 5 ans), cette étude analyse, en fonction du statut HPV de la tumeur et du point de vue des taux de contrôle de la maladie, du taux de survie globale et de la toxicité, l'équivalence entre une radiothérapie ipsilatérale et une radiothérapie bilatérale
Purpose/Objective : To report outcome of ipsilateral radiotherapy (RT-ipsi) for HPV-positive [HPV+] and HPV-negative [HPV–] T1-T2N0-N2b tonsil cancer treated 25 years after our initial historical cohort. Materials/Methods : T1-T2N0-N2b tonsil cancer patients receiving RT-ipsi or bilateral RT (RT-bilat) between 1999-2014 were reviewed. Overall survival (OS), local (LC), regional (RC), and grade 3-4 late toxicity (LT) were compared between RT-ipsi vs RT-bilat within HPV+ and HPV– patients, separately. Results : HPV status was ascertained in 379/427 (88%) consecutive cases (RT-ipsi: 62 HPV+, 34 HPV–; RT-bilat: 240 HPV+ 240, 41 HPV–). Proportion of ipsilateral RT by N-category for HPV+ and HPV– were: N0: 24/37 (65%) vs 28/48 (74%); N1: 21/49 (43%) vs 4/9 (44%); N2a: 10/39 (26%) vs 1/4 (25%); and N2b: 7/177 (4%) vs 1/24 (4%), respectively. 94/96 (98%) RT-ipsi were treated with RT-alone. Median follow-up was 5.03 years. Respective 5-year OS, LC, RC and LT were similar between RT-ipsi vs RT-bilat for the HPV+ [OS: 89% vs 87%, p=0.55; LC: 97% vs 98%, p=0.65; RC: 98% vs 97%, p=0.27; LT: 17% vs 12%, p=0.83] and HPV– [OS: 63% vs 48%, p=0.27; LC: 90% vs 80%, p=0.19; RC: 94% vs 83%, p=0.14; LT: 15% vs 22%, p=0.36]. Of the 96 RT-ipsi patients, contralateral neck failure (CNF) occurred in 1/52 HPV+ and 1/34 HPV– patients. The 5-year CNF rates were 2% (95%CI: 1-9) [HPV+: 2% (0-14); HPV–: 3% (0-21), p=0.66]. Five local [2 HPV+; 3 HPV–] and no distant failures were seen. Five-year LC, RC and LT were 97% vs 90% (p=0.24), 98% vs 94% (p=0.25), 18% vs 15% (p=0.75) for the HPV+ and HPV– cohort, respectively. Osteoradionecrosis occurred in 9 patients: 6/47 (13%) treated with conventional RT and 3/49 (6%) with IMRT (p=0.32). Conclusion : Ipsilateral radiation to selected T1-T2N0-N2b tonsil patients results in equally excellent outcomes regardless of tumor HPV status.