Surgeries of the Oral Cavity Malignancies

Anatomy of the Oral Cavity

Following are the main boundaries of the oral cavity.

• Anterior Boundary: It extends from the skin and the vermilion border of the lips.
• Posterior Boundary: It extends to the line of circumvallate papillae. Circumvallate papillae lie at the junction of the anterior two-thirds and posterior one-third of the tongue.
• Superior Boundary: It extends up to the junction of the hard and soft palate. The hard palate forms the roof of the oral cavity, separating the oral cavity from the nasal cavity.
• Lateral Boundary: It extends to the anterior tonsillar pillars.

Oral Cavity Subsites: Potential Sites for Oral Cavity Malignancies

• Lip: The mucosal surface.
• Oral Tongue: Anterior two-thirds of the tongue.
• Buccal Mucosa
• Floor of Mouth
• Hard Palate: Forms the roof of the oral cavity.
• Alveolar Ridge and Gums: Both upper and lower gums.
• Retromolar Trigoney
• Retromolar Trigone is an area of attached mucosa over the ascending ramus of the mandible, which lies posterior to the last molar tooth and extends superiorly onto the maxillary tuberosity.
  • Boundaries of Retromolar Trigone:
    • Superior: Maxillary tuberosity/ tubercle.
    • Inferior: Gingiva behind the third molar tooth.
    • Anterior: Third molar tooth (since the retromolar Trigone is posterior to the third molar).
    • Medial: Temporal crest of the mandible.
    • Lateral: Mucosal fold connecting maxilla and mandible.
  • The most common histological type of oral cavity cancer is squamous Cell Carcinoma (SCC).
  • Subtypes of SCC are Verrucous Carcinoma and Spindle Cell Carcinoma
  • Other Malignancies in the Oral Cavity:
    • Malignant Tumours of Minor Salivary Glands
    • Lymphomas: arising around the Waldeyer's ring.
    • Odontogenic Tumours
    • Mandibular Tumours
• The Most Common Site for Oral Cavity Cancers Worldwide is The lateral border of the anterior two-thirds of the tongue. The Most Common Site for Oral Cavity Cancers in India is the Buccal Mucosa, Specifically, the gingivobuccal sulcus (groove between the gingiva and the buccal mucosa).

Management Of Potentially Malignant Oral Cavity Lesions

Biopsy is Mandatory for diagnosis. The main aim of the biopsy is to Confirm pathological diagnosis and Determine the presence or absence of dysplasia (i.e., mild, moderate, severe).

Initial Management of potentially malignant oral lesions is done by

1. Lifestyle Modifications: Discontinue smoking, alcohol, and betel nut quid consumption.
2. Treat Underlying Causes: Address any sharp teeth or ill-fitting dentures.
3. Photographic Record: Maintain for monitoring and follow-up purposes.

The Definitive Treatment is by Surgical Excision. This is the Primary and most definitive treatment mandatory for erythroplakia, erythroleukoplakia, and proliferative verrucous leukoplakia. For homogeneous leukoplakia, Biopsy first; if dysplasia is present, surgical excision is needed. Although one must remember that Surgical removal does not completely eliminate malignancy risk. 

Alternatively, there are treatment Options like Laser Vaporization which Uses CO2 laser and Cryotherapy (Freezing and destroying abnormal cells)

Factors associated with Increased Risk for Malignancies in Pre-existing (dysplasia) Lesions

• Female Sex: While oral cavity cancer is more prevalent in males, females with potentially malignant oral lesions have a higher risk of malignant transformation.
• Size of the Lesion: Lesions larger than 200 mm² have a high risk of malignant transformation.
• Nature of the Lesion: Non-homogeneous lesions have a greater propensity to become malignant. For instance, non-homogeneous leukoplakia has a higher risk than its homogeneous counterpart.
• Non-smokers: Smoking is a significant risk factor for oral cavity cancer. However, presence of premalignant lesion in non-smokers have higher risk of malignant change.
• Presence of Multiple Lesions: Having multiple potentially malignant oral lesions in the oral cavity enhances the risk of at least one of them undergoing malignant transformation.
• Location of the Lesion: The site of the lesion in the oral cavity can influence its risk of malignant change. Some locations may have a higher predisposition than others.
• Age: The likelihood of malignant transformation increases with age.

Pathology/ Histology Of the Oral Cavity Lesions

Histological Grade or Differentiation of Tumour is done by using the Broder’s Classification:

• G1: Well-differentiated tumour
• G2: Moderately differentiated tumour
• G3: Poorly differentiated tumour

The pattern of Invasion is based on the shape of advancing front or border of tumour. The Worst Pattern of Invasion (WPOI) is a vital histological parameter for predicting the prognosis of oral cavity cancers, useful in stratifying oral cavity cancers into different risk groups. Following are the Grades of WPOI:

• Grade 1: Tumour invades in a broad pushing manner.
• Grade 2: Tumour invades in the form of solid cords or strands (finger-like invasion).
• Grade 3: Invasive islands of tumours contain more than 15 clusters of cells.
• Grade 4: Invasive islands of tumours contain fewer than 15 clusters of cells.
• Grade 5: Tumour islands are ≥ 1 mm away from the progressive border of the tumour.

Clinical Features Of Malignancies in the Oral Cavity

• Non-healing Ulcer: Any ulcer in the oral cavity that does not heal for over two weeks raise suspicion for malignancy.
• Persistent Neck Mass: Could be metastatic lymph nodes.
• Sore Tongue/Restricted Tongue Movement: Due to infiltration of the tongue musculature or extension to the floor of the mouth.
• Trismus (Difficulty in Opening Mouth): May arise from the involvement of pterygoid plates, temporomandibular joint, or the masticator space.
• Dysphagia: Difficulty in swallowing.
• Jaw/Facial Swelling: Could be due to mandibular involvement.
• Unexplained Tooth Mobility: Resulting from the involvement of tooth sockets.
• Sensory Nerve Deficit: Cranial nerves 7th, 10th, 11th, and 12th may get involved. Their examination is essential.
• Chronic Otalgia: Pain in the ear.
• Contact/Bleeding on Touch: Malignant ulcers often bleed when touched.
• Pain: At the primary site or can be referred pain.
• Nutritional Impairment: Resulting from difficulty in swallowing, restricted tongue movement, anorexia, and pain. Patients might present cachexia.

Investigation And Evaluation For Oral Cavity Cancer

• Tissue Diagnosis: It is the Gold standard for confirming oral cavity cancer. An incisional biopsy is done and the Sample taken from the most suspicious site with adjacent mucosa. Narrow deep biopsies are better than shallow broad biopsies.
• Examination Under Anesthesia (EUA): EUA is Used especially in patients with advanced disease. When a biopsy or complete assessment can't be done in an awake patient, EUA becomes necessary.
• FNAC (Fine Needle Aspiration Cytology) of Cervical Lymph Nodes: FNAC done when the cervical lymph nodes are enlarged and palpable. The Sensitivity of FNAC is 89% to 98%.

Imaging of the Oral Cavity

• Plain X-ray/Ortho Pentagram (OPG): It is done mainly for dental or prosthodontic evaluation. Plain X-ray has a limited role in case of mandibular or maxillary involvement. Useful for planning any prophylactic dental treatment before surgery.
• Ultrasound: It is used in the Screening or evaluating cervical lymph nodes. The Sensitivity of USG is 85% and the Specificity is  78.9%. The only limitation of an USG is that it has a limited role for assessing the oral tumour.
• CT (Computed Tomography): It Provides hard tissue details and helps in Identifying involvement of bony cortex, such as mandible or maxilla. It Reveals cartilaginous involvement. The Limitation of CT is that there is Image degradation in patients with dental amalgams or restorative dental material.
• MRI (Magnetic Resonance Imaging): It is Considered as the gold standard modality of choice for determining the primary extent of the oral cavity cancer and determining the soft tissue infiltration.
• PET-CT: It is Not a first line/ preferred imaging for patients of oral cavity cancer. The indications for PET-CT are:
  • Malignant cervical lymphadenopathy with an unknown primary.
  • Surveillance after non-surgical treatment of oropharyngeal SCC.
  • Recurrent disease.

Treatment of Oral Cavity Malignancies

• Surgery: This is the preferred method of treatment for oral cavity cancers.
• Radiotherapy: Used primarily if surgical resection is expected to cause significant functional and structural morbidity.
• Combined Modality: Surgery followed by radiotherapy.
• Chemoradiotherapy: Combines radiotherapy with concurrent chemotherapy.
• The choice of treatment option depends on:
  • Size of the tumour.
  • Stage of the tumour.
  • Site of the tumour.
  • The tumour's relationship to vital structures.
  • Patient's performance status.
• Tumours, which involve structures such as the masticator space, skull base, internal carotid artery, or pterygoid plates, are unresectable. Therefore, radiotherapy and chemotherapy are the primary treatment options for T4B tumours.
• Oral Cavity: Surgery is preferred treatment. Radiotherapy is an option but usually reserved for cases where surgery result in unacceptable structural/ functional morbidity.
• Nasopharyngeal, Oropharyngeal, Hypopharyngeal, Laryngeal Cancers, and Paranasal Sinus Cancers: Radiotherapy or combined radiotherapy and chemotherapy can be chosen as primary treatment options.

Management of the Neck in the Oral Cavity Lesions

Management of the neck is Crucial as oral cavity cancers can spread to cervical lymph nodes. We can perform Surgery like Neck Dissection to remove affected lymph nodes. Alternatively, Radiotherapy is Used to target cervical lymph nodes and surrounding tissues.

It's imperative that the treatment approach for the primary tumour and the neck remain consistent. If surgery is chosen for the primary tumour, surgical management (like neck dissection) should ideally be the choice for the neck as well. Similarly, if radiotherapy is chosen for the primary tumour, radiotherapy should also be used for the neck.

Reconstruction of the Oral Cavity

The Purpose of Reconstruction is to restore both aesthetic (appearance) and functional aspects. It also focuses on the restoration of critical functions include speech, chewing, swallowing and oral incontinence. The can be a huge Impact of Tumour Location on Function. For example Anterior Defects will Primarily affect speech more whereas, Posterior Defects primarily impact swallowing more.

Reconstruction should be done as soon as possible.

General principles for the treatment of oral cavity cancer:

• Healing by Secondary Intention: Leaving the wound open and allowing it to heal naturally.
• Primary Closure: Directly suturing the wound edges together.
• Skin Grafting: Transplanting a piece of skin to the wound site.
• Local Flaps: Using adjacent tissues to cover the defect.
• Regional Flaps: Using tissues from nearby regions with its blood supply.
• Free Vascular Flaps or Microvascular Free Tissue Transfer: Transferring tissues from distant sites, along with its blood supply, and reconnecting the blood vessels.

Surgery Of the Oral Cavity

Given the limited and complex nature of the oral cavity, gaining adequate access to the tumour is crucial. Peroral/ transoral access may not be sufficient for extensive disease/ large tumour involving surrounding structures to excise the tumour. Different techniques and approaches are employed based on tumour size, location, and relation to surrounding structures.

The type of surgery depends on the site + size of the tumour, depth of invasion and proximity to mandible and maxilla. The primary goal is to remove the tumour and ensure adequate margins. A wide local excision is often performed to ensure complete tumour removal and decrease the chance of recurrence. Principles of surgery:

• En block resection with neck dissection in continuity.
• Macroscopic margins should be minimum 1 cm circumferentially in all planes.
• Negative microscopic margin: when the distance between the resected margin and the tumour cell is ≥ 5mm.
• Close margin: 2-5mm 
• Positive margin: margins involve the tumour cells. 
• Nerve resection: in case of nerve involvement especially there is preoperative evidence of nerve involvement in the form of clinical nerve palsy.
• Segmental resection: send proximal and distant margin for frozen section.
• Cable graft repair: if margins are free.
• If adequate tumour margin cannot be obtained without sacrificing nerve, in that case also we go for nerve resection even there is no evidence of nerve involvement preoperatively.

Approaches for assessing oral cavity cancers should be made Anterior to the oral cavity cancers and smaller lesions can be excised through transoral approach and does not need any additional access procedure. Posteriorly located tumours are the tumours that need additional technique other than transoral approach.

Also Read: Rapid Acquisition Of Key Concepts Head And Neck

Frequently asked Questions

Q: What is the preferred method of treatment for oral cavity cancers?

Answer: Surgery

Q: what is the Histological Grade according to the Broder’s Classification for Poorly differentiated tumour?

Answer: Grade 3

Q: What is the Gold standard for confirming oral cavity cancer?

Answer: Tissue diagnosis or biopsy is the Gold standard for confirming oral cavity cancer.

Q:  Anterior tonsillar pillars form which boundry of the oral cavity?

Answer: Lateral boundry

Hope you found this blog helpful for your NEET SS Surgery head and neck preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.