Cancer of retromolar trigone: Long‐term radiation therapy outcome

Abstract

Background. Cancer of the retromolar trigone is an uncommon head and neck cancer. In this retrospective study, we identified the prognostic factors and evaluated the therapeutic outcomes of patients treated with preoperative radiation therapy (RT), postoperative RT, and RT alone.Methods. Between 1971 and 1994, 65 patients with histologically proven epidermoid carcinoma of the retromolar trigone were treated at the Mallinckrodt Institute of Radiology; 10 patients received preoperative RT (30-55.2 Gy), 39 received postoperative RT (46-66.6 Gy), and 15 were treated with RT alone (63-74 Gy). Surgery included 44 composite resections and 7 wide excisions. The minimum follow-up was 5 years.Results. The 5-year disease-free survival rates were 90% with preoperative RT, 63% with postoperative RT, and 31% with RT alone. The 5-year disease-free survival rates were 76% for patients with T1 disease, 50% for T2, 72% for T3, and 54% for T4. The 5-year disease-free survival rates were 69% for patients with NO disease, 56% for N1, and 26% for N2. The locoregional recurrence rates were 10% (1 of 10) for preoperative RT, 23% (9 of 39) for postoperative RT, and 44% (7 of 16) for RT alone. On multivariate analysis, the significant factors for disease-free survival were treatment modality (p = .002) and N stage (p = .012); for locoregional control it was treatment modality (p = .046); and for distant metastasis it was N stage (p = .002). The incidence of bone necrosis, soft tissue necrosis, and severe trismus was 12% with postoperative RT, 11% with RT alone, and none with preoperative RT.Conclusions. Combination surgery with postoperative or preoperative RT offers better locoregional control and disease-free survival than RT alone for epidermoid carcinoma of the retromolar trigone. Lymph node status significantly influences the disease-free survival and distant metastasis rates.

Controversies in the management of retromolar trigone carcinoma

“…The tumor spreads to the anterior pillar in 80% to 84.5% of the cases and the majority of them invade 3 or more subsites of the oral cavity and oropharynx. [8][9][10] Despite this tendency to spread to the anterior pillar, the majority of the authors study these subsites separately. In fact, RMT cancer is more prone to bone invasion because of its close proximity to the mandible and the maxilla.…”

“…Out of 14 studies published on RMT cancer treatment in the English-language literature between 1959 and 2007, only 6 of them compared 2 or more treatment modalities. 1,9,10,15,27,28 In the other studies, patients receive 1 treatment modality (surgery or radiation therapy) and the results are compared to historical series. However, patient and tumor characteristics are not comparable between these studies, and the reported outcomes are not uniform.…”

“…5,9,11 Reports of controlateral neck metastases are anecdotal. [8][9][10] Thus, bilateral neck dissection is recommended only if the lesion crosses the midline anteriorly in the oral cavity or posteriorly in the oropharynx. The modality of treatment of the N1 neck should be the same as the primary.…”

“…In this study, multivariate analysis showed that combined treatment significantly improved local control, local-regional control, distant metastasis-free survival, cause-specific survival, and overall survival. Huang et al studied 65 patients in 3 treatment groups: definitive RT (n 5 15), preoperative RT (n 5 10), and postoperative RT (n 5 39) 10 . The minimum followup was 5 years.…”

Treatment outcomes of patients with primary squamous cell carcinoma of the retromolar trigone

“…Primary retromolar trigone (RMT) SCC, though less frequently observed (5.6% vs. 45.2% oral tongue SCC), poses a unique challenge to surgeons, as early mandibular invasion and regional metastases are not uncommon . Factors complicating management are extension to the buccal mucosa, tonsillar pillar, and soft palate …”