Definitive radiotherapy for squamous cell carcinoma of the oral cavity: a single-institution experience.

BACKGROUND: Surgery is standard of care for oral cavity cancer (OCC). We provide a single-institution experience using definitive radiotherapy (RT) with or without concurrent systemic therapy for primary unresectable OCC. PATIENTS AND METHODS: We retrospectively examined 49 patients with non-metastatic primary unresectable OCC treated with definitive RT between 2000 and 2019. The majority of patients (63.3%) were treated with definitive chemoradiotherapy while 26.5% were given single-agent cetuximab weekly simultaneous to definitive RT. Five patients were treated with definitive RT alone because of limited disease and no nodal involvement. RESULTS: Median follow-up was 73 months (range, 6-236 months), median progression free survival (PFS) was 42 months (range, 2-157 months), median local disease-free survival (LDFS) was 44 months (range, 2-157 months) and median overall survival (OS) from the time of RT initiation was 52 months (range, 5-236 months). There were 65.3% locoregional failures, 84.4% local and 15.6% distant metastasis. The majority of patients with local failure presented with American Joint Committee on Cancer (AJCC) Stage III-IV disease (59.2%). The 5-year Kaplan-Meier estimates for OS (III-IV vs. I-II) was 22.8% vs. 54.2 % (p = 0.03, HR 2.090, 1.1-4.2). Patients who were treated with systemic therapy had a significant better 5-year overall survival compared to those with RT alone (43.9% vs. 23.1%, p = 0.05, 1.0-4.1). RT with doses less than 70 Gy (p = 0.046, HR 2.1 (1.0-4.5) was associated with worse overall survival. Mucositis was the most common ≥ grade 3 acute toxicity and occurred in 19 patients (39%). Incidences of chronic toxicities were loss of taste, trismus, osteoradionecrosis and xerostomia. CONCLUSIONS: Definitive RT with or without concurrent systemic agents in patients with unresectable OCC resulted in an eloquent rate of locoregional control and good overall survival rates and is currently the best available treatment option in this patient collective.

Intensity Modulated Radiotherapy (IMRT) With Carbon Ion Boost in the Multimodal Treatment of Salivary Duct Carcinoma.

Background: To assess outcomes and treatment related toxicity following intensity-modulated radiotherapy (IMRT) and a Carbon Ion Radiotherapy (CIRT) boost for salivary duct carcinoma (SDC). Methods: Twenty-eight consecutive patients with SDC who underwent a postoperative (82%) or definitive (18%) radiation therapy between 2010 and 2017 were assessed in this retrospective single-center analysis. CIRT boost was delivered with median 18 Gy(RBE) in 6 daily fractions, followed by an TomoTherapy®-based IMRT (median 54 Gy in 27 daily fractions). Treatment-related acute toxicity was assessed according to CTCAE Version 4. Results: Tumors were most commonly located in the major salivary glands (n = 25; 89%); 23 patients (82%) received previous surgery (R0: 30%; R1: 57%; R2: 4%; RX: 19%). Median follow-up was 30 months. Four patients (14%) experienced a local relapse and 3 (11%) developed locoregional recurrence. The two-year local control (LC) and locoregional control (LRC) was 96 and 93%, respectively. Median disease-free survival (DFS) was 27 months, metastasis-free survival (MFS) was 69 months, and overall survival (OS) was 93 months. Acute grade 3 toxicity occurred in 11 patients (mucositis, dermatitis, xerostomia; n = 2 each (7%) were the most common) and 2 osteonecroses of the mandibular (grade 3) occurred. No patients experienced grade ≥4 toxicities. Conclusions: Multimodal therapy approaches with surgery followed by IMRT and CIRT boost for SDC leads to good local and locoregional disease control. However, the frequent occurrence of distant metastases limits the prognosis and requires optimization of adjuvant systemic therapies.

Intensity Modulated Radiotherapy (IMRT) + Carbon Ion Boost for Adenoid Cystic Carcinoma of the Minor Salivary Glands in the Oral Cavity.

BACKGROUND: Adenoid cystic carcinoma (ACC) are more common in the minor salivary glands (MiSGs) than the major salivary glands, and are characterized by slow tumor progression and frequently local recurrence. The main treatment option is surgery followed by combined radiotherapy. METHODS: A retrospective analysis contained 67 patients with ACC of MiSGs in the oral cavity who underwent surgery followed by radiotherapy. The median cumulative IMRT dose was 50 Gy followed by 24 Gy for carbon ion (C12) boost. Median follow-up was 40 months. RESULTS: Median 5-years overall survival (OS), progression-free survival (PFS) and local disease-free survival (LDFS) rates were 85.5%, 57.4% and 74.9%. Median time until progression was detected was 32 months (range: 2⁻205 months). Early grade ≥3 mucositis, dermatitis, and dysphagia were detected in 52.2%, 7.5% and 11.9% respectively. Besides common toxicities, two patients (3.0%) developed grade 3 toxicities with osteoradionecrosis of the jaw after 18 and 66 months. Higher-grade late toxicity (CTCAE grade 4) was not detected. No treatment-related death was detected. CONCLUSIONS: Our results demonstrate that postoperative combined radiotherapy with IMRT plus C12 boost seems to be a feasible and effective treatment method in ACC of MiSGs in the oral cavity, with good control and survival rates and adequate toxicity.