LOCALLY VERY ADVANCED ORAL (MOUTH) CANCER(STAGE 4B):

Locally very advanced oral cancer (Stage 4B) refers to tumours that are large and have invaded deep, critical structures such as the skull base bones, internal carotid artery, or deep facial spaces (masticator space). These cancers are complex to treat and often require a multimodal approach, including surgery, radiation, and chemotherapy, to achieve disease control.

Although survival rates are lower in Stage 4B disease, advances in reconstructive surgery and novel therapies are improving functional and oncological outcomes.

Surgery for Locally Very Advanced Oral Cancer (Stage 4B)

Infratemporal Fossa (ITF) Clearance

Infratemporal fossa (ITF) clearance is a highly specialized surgical procedure that involves compartmental removal of all soft tissue and bony structures within the infratemporal fossa to achieve oncologic control in advanced head and neck malignancies.

The infratemporal fossa is a complex anatomical region that serves as a vital conduit for neurovascular structures between the brain and the face.

Standard ITF clearance involves removal of:

Muscles
Veins and arteries
Nerves and their sensory branches

Sub-Compartmentalization Framework

The infratemporal fossa is divided into three primary compartments and several sub-compartments based on anatomical structures and imaging findings.

Compartment 1: Low ITF

Prognosis: Generally considered “surgeon-friendly”
Associated with favourable surgical outcomes

Compartment 2: Anterior High ITF

Prognosis: Clinical outcomes comparable to Low ITF (Compartment 1)
Often resectable with favourable outcomes

Compartment 3: Posterior High ITF

Further subdivided into 3a, 3b, and 3c
Compartment 3c shows the poorest response and highest rates of disease progression

Survival Outcomes

No significant difference in progression-free survival (PFS) between Compartments 1 and 2
Compartment 3, particularly 3a and 3c, demonstrates significantly worse survival outcomes

Management Strategy

Involvement of Compartments 3a, 3b, or 3c often requires neoadjuvant chemotherapy to downstage the tumour before attempting surgery
Disease limited to Compartments 1 or 2 may be considered for upfront surgery and generally has better survival after resection

Indications for ITF Clearance

ITF clearance is primarily indicated for advanced malignant tumours that originate within or invade the infratemporal fossa.

Common Indications Include:

Advanced Oral Cavity Cancer (T4b):Especially gingivo-buccal complex cancers extending into the masticator space
Sinonasal Malignancies:Maxillary sinus tumours extending through the posterior wall into the pterygopalatine and infratemporal fossae
Nasopharyngeal Carcinoma:Recurrent or extensive disease involving the lateral skull base
Skull Base Tumours:Chordomas, chondrosarcomas, or glomus tumours encroaching upon the ITF

ITF clearance may offer a curative option for patients who would otherwise be limited to palliative care.

Complications and Rehabilitation

Due to the extensive nature of ITF clearance, significant functional and aesthetic changes may occur.

Common Complications

Trismus: Severe jaw stiffness due to removal or scarring of masticatory muscles
Neurosensory Loss: Numbness of the tongue, gums, and face following sacrifice of V3 branches
Facial and Dental Changes: Jaw deviation following mandibular condylectomy
Reconstruction: Large defects often require microvascular free flap reconstruction to fill dead space and protect exposed structures such as the internal carotid artery or dura

Rehabilitation After ITF Clearance

1. Trismus (Jaw Stiffness) Management

Trismus is a hallmark complication following ITF clearance.

Preventive Exercises:Massage and circular motion exercises for the masseter muscles are encouraged preoperatively or soon after initial healing
Active and Passive Stretching:Includes mouth opening for 10-second intervals and side-to-side jaw movements
Mechanical Devices:Devices such as TheraBite or TrisCaRe provide controlled jaw stretching and can improve mouth opening by 5–10 mm, even in severe cases

2. Swallowing and Nutrition

Swallowing is often affected due to proximity of the ITF to pharyngeal muscles and tongue nerves.

Dietary Progression:Begins with nasogastric tube feeding, followed by thickened liquids and gradual transition to a regular diet based on videofluoroscopic assessment
Swallowing Therapy:Techniques include the Chin-Tuck Maneuver (airway protection) and the Mendelsohn Maneuver (strengthening swallowing muscles)
Electrical Stimulation:Neuromuscular electrical stimulation may be used to support swallowing rehabilitation

3. Speech and Facial Nerve Rehabilitation

Articulation Exercises:Speech-language pathologists focus on improving speech intelligibility through targeted exercises
Nerve Grafts:Secondary surgical procedures may be performed if the facial nerve is sacrificed to restore facial tone and symmetry

4. Early Mobilization and General Recovery

Immediate Postoperative Period (First 24–48 Hours):Bed rest for flap monitoring, followed by assisted sitting and deep-breathing exercises
Hospital Stay:Typically 6–8 days, until patients regain independent mobility and oral hygiene control
Long-Term Surveillance:Regular follow-ups every 3–6 months, including MRI or CT scans, to monitor recurrence and adjust rehabilitation or pain management

Conclusion

Despite its complexity and associated risks, infratemporal fossa clearance provides a viable pathway for local disease control in selected patients with locally very advanced oral cancer. Studies demonstrate improved disease-free survivalwhen negative surgical margins are achieved.