Introduction
The buccal mucosa is an uncommon site for oral cavity cancer (SCC) and comprises 5% to 10% of all intraoral squamous cell carcinoma (IOSCC) in North America and Europe. However, it is more commonly seen among Taiwanese Chinese and in India, where betel nut chewing is prevalent in these communities. Among the published reports, buccal SCC was found to comprise between 23% and 37% of all IOSCC in a Taiwanese cohort. Most patients with buccal SCC are in the fifth to sixth decade of life, and other risk factors, such as smoking and alcohol consumption, are also commonly encountered in these patients.
Treatment of buccal SCC is primarily wide surgical excision with negative margins, followed by adjuvant radiation or chemoradiation, depending on adverse clinicopathologic features. In patients with gross local disease that is unresectable (e.g., involvement of internal carotid artery), treatment is usually palliative radiation. Complete excision of buccal SCC lies in the thorough understanding of the three-dimensional surgical anatomy of the buccal space and its relevant surrounding areas, so as to anticipate possible spread of the cancer and avoid leaving microscopic disease behind in the surgical field.
Key Operative Learning Points
- 1.
Buccal SCC is in close proximity to the underlying buccal space, which can potentially lead to subclinical infiltration of the masticator space, infratemporal fossa, and pterygopalatine fossa.
- 2.
Surgery for buccal SCC requires a thorough three-dimensional understanding of the related surgical anatomy so as to achieve complete surgical extirpation.
- 3.
Due to the proximity of the buccal space to the retromolar trigone and the inferior and superior alveolar ridges marginal mandibulectomy and/or inferior maxillectomy may be necessary to achieve wide surgical margins. Similarly, excision of the skin of the cheek may be necessary for deep infiltration of the tumor to the dermis.
- 4.
Reconstruction of the surgical defect is necessary to reconstitute both form and function of the oral cavity. Specifically, reconstitution of the oral commissure may be necessary to prevent drooling in the postoperative period.
Preoperative Period
History
- 1.
History of presenting illness
- a.
The duration and progression of the buccal primary should be ascertained.
- b.
Local complications such as bleeding should be assessed. Speech and swallowing impairment may also occur due to fixation of the tongue by the cancer.
- c.
Trismus should be assessed because it may signify posterior extension into the pterygoid muscles, or it may result from submucosal fibrosis from chronic betel nut chewing among these patients.
- d.
Risk factors such as alcohol ingestion, smoking, and betel nut chewing should be sought.
- a.
- 2.
Past medical history
- a.
Previous history of cancer of the head and neck and previous treatment with either surgery or radiotherapy are important for management.
- b.
The patient’s overall medical condition should be thoroughly evaluated for assessment of perioperative anesthetic risks.
- c.
Antiplatelet agents may increase perioperative bleeding and should be omitted before surgery. The decision to either stop or bridge the need of anticoagulation should be made with the patient’s primary medical physician.
- a.
Physical Examination
- 1.
Examination of the oral cavity
- a.
All oral cavity subsites should be examined for possible synchronous cancers or premalignant lesions.
- b.
The patient’s ability to open his or her mouth should be evaluated for trismus and its severity. This may be a sign of medial pterygoid muscle involvement by the cancer. This may either represent unresectability or signify the need of a combined skull base approach to have complete tumor extirpation.
- c.
Intraoral extension to the tongue, gingival, superior or inferior alveolar ridge, and retromolar trigone ( Fig. 31.1 ) is evaluated.
Fig. 31.1
Right buccal squamous cell carcinoma with involvement of retromolar trigone.
- d.
The mobility of the tongue is assessed for involvement of the extrinsic tongue muscles.
- e.
The distance of the cancer from the oral commissure should be measured. This allows the surgeon to identify whether some form of oral competence reconstitution will be necessary following resection.
- f.
Bimanual palpation should be also performed to identify possible fixation of the cancer to the overlying dermis. A peau d’orange appearance of the cheek skin, if present, is an accurate indicator of subdermal lymphatic infiltration by the cancer.
- g.
Facial nerve function should be assessed, in particular the function of the buccal branch with regard to upper lip elevation and symmetry of the nasolabial fold.
- a.
- 2.
Nasoendoscopy
- a.
Nasoendoscopy is performed to evaluate for extension of the cancer to the nasal cavity in instances when the hard palate is involved.
- b.
The upper airway should be evaluated, especially in patients with trismus, so as to anticipate a possible difficult airway during induction of general anesthesia.
- c.
Possible second primary cancers of the head and neck should be excluded.
- a.
- 3.
Head and neck examination
- a.
The neck is examined for possible cervical lymph node metastasis.
- b.
The sensation of the lower teeth is assessed as it may be affected due to involvement of the inferior alveolar nerve.
- a.
Imaging
Computed Tomography (CT) Scan
CT gives reliable information on extension into bone, especially if involvement of the mandible is suspected. CT has been shown to achieve 100% sensitivity and 88% specificity for assessment of invasion of the mandibular cortex.
Magnetic Resonance Imaging (MRI)
MRI is frequently used to evaluate the deep extension of the buccal SCC because it gives excellent visualization of the masticator space, infratemporal fossa, and pterygopalatine fossa. Features of masticator space involvement include extension of soft tissue mass to the masticator space, effacement of the masticator adipose tissue, infiltration of the muscles of mastication, such as the pterygoid muscles, and destruction of the ramus of the mandible. Displacement of adipose tissue by cancer within the pterygopalatine fossa on noncontrasted T1-weighted imaging is a sign of posterior extension into the pterygopalatine fossa.
MRI imaging also carries a higher sensitivity in detecting perineural spread as compared with CT. MRI features of perineural invasion include enhancement of the nerve, nerve enlargement, and widening of the respective neural foramina.
Angiography
Angiography is seldom required unless there is suspicion of encasement of the internal carotid artery.
Indications
- 1.
T1-T4a buccal SCC
- 2.
Select T4b cancer (masticator space involvement that is inferior to the mandibular notch)
Involvement of the masticator space is classified as T4b disease by the American joint consensus committee (AJCC) 2002 staging system. This classification is defined as such because any involvement of the masticator space will imply incomplete surgical eradication of cancer due to the free communications to the deeper infratemporal and pterygopalatine fossa. In this instance, a compartmentalized resection of cancer will be unachievable.
However, clinical studies suggest that selected cancers with limited invasion of the masticator space might benefit from surgical extirpation. In a retrospective study performed by Liao et al., 45 patients with T4b oral cavity SCC (majority buccal SCC) underwent surgical resection. Patients with involvement of the masticator space that was inferior to the mandibular notch achieved improved disease-free survival than did patients with extension beyond the mandibular notch.
- 3.
Surgery is rarely performed for palliation, although it may be necessary to palliate a fungating cancer that is bleeding.
Contraindications
- 1.
Involvement of the masticator space that is superior to the mandibular notch
- 2.
Involvement of the infratemporal fossa, pterygopalatine fossa, and encasement of internal carotid artery by cancer
- 3.
Preexisting medical conditions that carry significant perioperative anesthetic risks
Preoperative Preparation
- 1.
Three-dimensional perception of the buccal SCC should be appreciated with clinical examination and radiologic assessment
- 2.
The defect following surgery should be anticipated and communicated with the reconstructive surgeon.
Operative Period
Surgery is the mainstay of treating buccal SCC, and it aims to completely resect the tumor with negative margins. A wide 2-cm margin surrounding the tumor is mapped out prior to resection.
Anesthesia
General Anesthesia
General anesthesia is typically used in order to control the upper airway during surgery. An orotracheal tube is typically used and with the tube positioned opposite to the side to be resected. Alternatively, a nasotracheal tube may be used, and the advantage is that it allows a fuller visualization of the oral cavity. In locally advanced cancers, a planned tracheostomy is often created for the purpose of airway control postoperatively. This is often performed when a bulky flap is anticipated for reconstruction of the buccal space defect.
Positioning
Supine
The patient is placed supine, and a shoulder roll is placed for mild neck extension. When a free microvascular flap or a pedicled muscle flap is required, the donor site is exposed to allow for concurrent surgery.
Preoperative Antibiotic Prophylaxis
Antibiotics with appropriate anaerobic coverage are ideally chosen for perioperative antibiotic prophylaxis. A broad-spectrum antibiotic, such as amoxicillin with clavulanate, may be used. In patients with penicillin allergy, clindamycin is a good alternative.
Instruments and Equipment to Have Available
- 1.
A mouth gag (e.g., Jennings gag) is useful to expose the entire buccal mucosa.
- 2.
An oscillating saw should be available when a mandibulectomy is anticipated.
Key Surgical Anatomy and Clinical Implications
Buccal Space
The buccal mucosa is composed of nonkeratinizing squamous epithelium, which is where SCC arises. Deeper to this mucosal layer lies the buccinator muscle, which forms the medial boundary of the buccal space. The buccal space and adjacent masticator space are important anatomic spaces because they communicate with the infratemporal fossa and pterygopalatine fossa via the foramen ovale and pterygomaxillary fissure, respectively ( Fig. 31.2 ). Therefore involvement of these spaces by the cancer may be associated with extension into these deeper anatomic spaces.
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