The oral cavity possesses complex functional anatomy with regard to speech, swallowing and facial projection. Oral cavity includes lip, tongue, floor of mouth, mandible (jaw bone) and gum, retromolar trigone (RMT), buccal mucosa(cheek), and hard-palate (roof of mouth). Most common pathological diagnosis for oral cavity cancer is squamous cell carcinoma.
On initial evaluation, careful physical examination specially, alterations in speech, articulation, tongue mobility (suggest involvement of the extrinsic tongue muscle and hypoglossal nerve), poorly fitting dentures or lose teeth (suggest alveolar bone invasion) cranial neuropathies (suggest nerve invasion) and trismus (indication for pterygoid muscles involvement or masticator-space invasion) and neck node palpation are very important for future treatment decision.
Radiographic imaging is essential in the preoperative work-up to assess primary tumour, regional disease and distant disease. CT scan with intravenous contrast for assessment of bone invasion, nodal involvement as well as soft tissue extent of primary disease. MRI is superior for visualisation of soft tissue and cranial nerve neuropathy. FDG-PET can be used for detection of distant metastasis, especially in locoregionally advanced disease.
One of the most important aspects of pre-treatment planning is assessment of patient and patient’s disease status by members of a multidisciplinary oncology team (head and neck surgeon, plastic and reconstructive surgeon, dedicated Radiation Oncologist, Medical Oncologist, dentist) and rehabilitative teams for improved treatment and functional outcome as well as improved quality of life of patient.
The National Comprehensive Cancer Network (NCCN) recommends surgery for patients with early-stage tumours and advanced-staged tumours. Adjuvant radiotherapy needed depending upon histopathology report. Concurrent chemotherapy is used for positive surgical margin and extra nodal involvement present on histopathology report.
The goals of surgery are for complete resection of the primary tumour with negative margins, staging and treatment of regional lymphatics. Approaches to oral cavity resection are dictated by the location and extent of invasion. The ability to obtain clear, three-dimensional margins is the most important factor in selecting the surgical approach.
Lesions of the anterior or lateral oral tongue can be resected trans orally; however, in cases with significant posterior extent and/or in patients with trismus, a pull-through or lip-splitting incision with mandibulotomy—may be required for optimal resection.
Buccal resections can be performed with a transoral approach or with a lip-split incision to allow adequate exposure for mandibular or maxillary resection. Retromolar trigone resections often require mandibulectomy because of the posterior extent and increased rate of bone invasion. The introduction of transoral robotics surgery offers a novel approach for resecting more posterior tumors without mandibulotomy, especially for soft palate, tonsils, base of tongue cancer.
In many cases, FOM cancers can be resected trans orally, and these excisions often involve marginal or segmental mandibulectomy. The presence of mandibular invasion is associated with worsened LRC. Mandibular resection is based on preoperative assessment of invasion of the periosteum and cortex. If mandible is involved, then segmental mandibulectomy or hemimandibulectomy is required. Reconstruction of mandible can be achieved with free fibula osteocutaneous free flap, which helps in better functional and cosmetic outcomes. Tongue and buccal mucosa can be reconstructed with local, regional or free flap. For more than hemiglossectomy defect, soft tissue free flap in the form of radial forearm free flap or anterolateral thigh free flap (ALT) gives better functional outcomes.
Advanced stage oral cavity patient needs adjuvant radiotherapy depending upon histopathology report. Now a day, IMRT has replaced standard delivery of radiotherapy and has improved control of radiation -associated toxicities and enhanced post treatment quality of life especially dry mouth and fibrosis over radiation field.
