Treatment Outcomes for Primary Retromolar Trigone Carcinoma: A Single Institution Experience

Retromolar trigone (RMT) is a rare location for oral cavity cancers. RMT cancers are aggressive malignancies that mostly present at an advanced stage. In this study, we aimed to evaluate treatment outcomes in patients who underwent initial radical surgical resection and postoperative radiotherapy or chemoradiotherapy with a diagnosis of primary RMT squamous cell carcinoma in our institution.

The study included 20 primary RMT tumor patients out of 191 oral cavity cancer cases treated from January 2010 through December 2019. We retrospectively analyzed treatment details, histopathology reports, postoperative clinical course and survival outcomes.

The mean age at presentation was 59.4 years. Eighty percent of all patients were either stage 3 or stage 4. We performed mandibular resection in 14 patients (70%) and partial maxillectomy in eight patients (40%). Nineteen patients (95%) underwent unilateral neck dissection. The incidence of metastatic cervical lymph node was 13/20 (65%). Overall survival (OS) and disease-free survival (DFS) rates during follow-up (mean 26.3 months) were 60% and 75%, respectively. There was statistical significance between presence of multilevel metastatic lymph nodes and OS (p=0.013). DFS and OS of early stage and advanced stage groups were 100% vs 75% and 100% vs 50%, respectively, with no statistical significance (p=0.189 and p=0.084).

The survival of advanced stage RMT cancer is poor despite appropriate treatment. Bone involvement that necessitates resection is common due to the proximity of the tumor to the mandible and the maxilla. Multilevel positive cervical lymph nodes and advanced stage are poor prognostic factors.