ESTRO meets Asia 2024 - Abstract Book

S173

Interdisciplinary – Head & neck

ESTRO meets Asia 2024

Oral cavity squamous cell carcinoma (OCSCC) is rare in the Western population but higher prevalence in the Asian population contributing to significant mortality in globally diagnosed head and neck cancers. OCSCC is an aggressive cancer, with tendency to invade locally and metastasise distally. Multi-modality management approach to treating locally advanced OCSCC (LA-OCSCC) is favoured. Surgery remains the preferred primary treatment option followed by adjuvant treatments including radiotherapy, to reduce risk of local/distal recurrence and increase the chance of cure. In cases where surgery is contraindicated, definitive radiotherapy is offered as the primary treatment modality.

This study comprehensively assessed the survival outcome and local recurrence of LA-OCSCC treated with radiotherapy, either as adjuvant or definitive radiotherapy.

Material/Methods:

This is a retrospective analysis on LA-OCSCC treated with curative-intent in a single United Kingdom tertiary, university teaching hospital. All LA-OCSCC patients treated between 2012 and 2022 were included with groups treated with either post-operative adjuvant radiotherapy or definitive radiotherapy. Patients who recurred before starting adjuvant treatments were excluded. Radiotherapy is delivered using photon external beam radiotherapy with intensity-modulated radiation radiotherapy (IMRT) or volumetric modulated arc therapy (VMAT) with a standard adjuvant dose fractionation of 60Gy in 30 fractions treated over 6 weeks. In the patient with high risks features, the radiotherapy dose fractionation can be escalated to 66Gy in 33 fractions treated over 6.5 weeks. The radiotherapy target volume is the primary surgical site with additional margins and inclusion of elective neck nodal volumes deemed to be at risks of recurrence. Chemotherapy with weekly platinum (Cisplatin/ Carboplatin) is given concurrently with radiotherapy in the adjuvant setting for two main indications which are positive or close surgical margin and evidence of extracapsular spread. Local institutional audit approval was obtained. Radiotherapy, surgery, tumour characteristics, patient demographics, survival outcome and recurrence were collected from electronic records. Statistical analyses using SPSS (Version 26.0) software performed. Progression free survival (PFS) and overall survival (OS) were calculated. Basic statistics and Kaplan-Meier estimate was used to provide survival outcomes and recurrence rates.

Results:

Patient characteristics

100 (73.5%) patients were treated with primary surgery followed by adjuvant radiotherapy and 36 (26.5%) patients in definitive group, respectively.

The age of diagnosis of patients ranged from 28-98. Patients treated with post-operative adjuvant radiotherapy had better WHO performance status, higher tumour TNM8 staging and less comorbidities. Majority of patients has smoking history; 77.8% of definitive group and 70% of adjuvant groups.

The median follow-up time in months were 20 months and 13 months for adjuvant and definitive patients respectively.

Survival

Median PFS were 17 months and 13 months for adjuvant and definitive, respectively. (p-value of 0.947). Median OS were 61 months and 43 months for adjuvant and definitive respectively. (p-value of 0.154).

Recurrence