Radiation therapy for cT1-2 carcinoma of the palatine tonsil diagnosed via a simple tonsillectomy: Dosimetry and patterns of care in the IMRT era

Objective: Small carcinomas of the palatine tonsil are often diagnosed via simple tonsillectomy, a maneuver with non-therapeutic intent. Herein, practice patterns for this unique situation are evaluated.

Patients and methods: A retrospective review was performed across 10 facilities to identify patients with cT1-2 squamous carcinomas of the tonsil diagnosed by simple tonsillectomy between 2010 and 2018. Patients who received curative-intent intensity modulated radiotherapy (IMRT) without additional surgery were included. Target volumes were reviewed, and cumulative incidences of local failure and severe late dysphagia were calculated.

Results: From 638 oropharyngeal patients, 91 were diagnosed via simple tonsillectomy. Definitive IMRT with no additional surgery to the primary site was utilized in 57, and three with gross residual disease were excluded, leaving 54 for analysis. Margins were negative in 13%, close (<5 mm) in 13%, microscopically positive in 61%, and not reported in 13%. Doses typically delivered to gross disease (68-70.2 Gy in 33-35 fx or 66 Gy/30 fx) were prescribed to the tonsil bed in 37 (69%). Sixteen patients (29%) received doses from 60 to 66 Gy (≤2 Gy/fx) and one received 50 Gy (2 Gy/fx). No local failures were observed. One late oropharyngeal soft tissue ulcer occurred, treated conservatively (grade 2). At five years, the cumulative incidence of severe late dysphagia was 17.4% (95% CI 6.1-28.8%).

Conclusion: Small tonsil carcinomas diagnosed by simple tonsillectomy represent a niche subset with favorable oncologic outcomes. Regardless, radiation oncologists tend to deliver full-dose to the tonsil bed. The necessity of this routine could be questioned in the modern era.