Excision of Cancer of the Floor of the Mouth

Introduction

Cancer of the floor of the mouth accounts for approximately one-third of all cancers of the oral cavity, with squamous cell carcinoma accounting for more than 95% of cases. Affected patients tend to reflect many of the epidemiologic features that have come to define squamous cell carcinoma of the head and neck as a whole, including a male predilection, advanced age at the time of diagnosis, and a well-established etiologic association with tobacco, alcohol, and human papillomavirus (HPV) ( Fig. 30.1 ). Despite these similarities, cancers of the floor of the mouth distinguish themselves from other cancers of the head and neck in several key ways. Perhaps most notable is its propensity for early occult metastasis to the cervical lymph nodes. Although positive nodal status is anticipated and even expected with advanced-stage cancers (T3/T4), occult nodal metastasis is a relatively common finding, even with early-stage cancer of the floor of the mouth (T1/T2). Retrospective reviews have demonstrated that as many as 30% of patients with a cancer of the floor of the mouth have evidence of occult nodal metastasis following elective neck dissection. This unique finding makes the treatment of the clinically negative neck a pivotal decision. Advanced-stage cancers of the floor of the mouth pose further challenges, as the intimate anatomic relationship between the floor of mouth and adjacent structures—namely the tongue and mandible—increases the risk of locoregional invasion. As the extent of the cancer increases, so does the associated morbidity of surgical intervention, including compromise of speech, mastication, and oral competence. Together, these distinct oncologic features combine to make cancer of the floor of the mouth one of the more aggressive and potentially lethal neoplasms of the oral cavity.

Fig. 30.1, Squamous cell carcinoma of the floor of the mouth is highly associated with the consumption of tobacco and alcohol.

Key Objective Learning Points

1.
Patient selection and careful preoperative planning are essential for optimizing oncologic and functional outcomes.
2.
Reconstructive efforts should aim to provide reasonable cosmesis while restoring competent physiologic function to both speech and swallowing.
3.
Airway planning, both at the time of surgery and during the postoperative recovery, is critical for limiting morbidity and mortality.
4.
The role of the elective neck dissection remains controversial but appears to offer a survival benefit.

Preoperative Period

A careless preoperative evaluation can compromise even the most elegantly performed surgery. Thus a systematic approach to patient selection is critical not only for determining surgical candidacy but also for maximizing oncologic and functional surgical outcomes. The foundation of the preoperative evaluation is the history and physical examination. The information obtained here should form a complete appreciation of the patient’s overall condition and thus his or her ability to undergo surgery safely. Although age itself is not a contraindication to surgery, numerous studies have demonstrated a relationship between the severity of medical comorbidities and postoperative survival. Those patients with numerous comorbidities will require medical evaluation and clearance as well as risk stratification. Thus assessment of surgical candidacy typically requires a multidisciplinary approach, which includes evaluations by internal medical specialists, medical and radiation oncologists, speech and swallow therapists, nutritionists, and anesthesiologists.

For those deemed fit enough to undergo surgical resection, the surgeon must next assess the resectability of the cancer. The history and physical examination along with a panorex computed tomography (CT), and magnetic resonance imaging (MRI) should allow for accurate staging of the tumor. Particular attention is paid to the presence of local invasion into surrounding structures of the oral cavity. An accurate assessment of the relationship of the cancer to the lingual surface of the mandible helps to define surgical planning and approach. Conversely, failure to recognize periosteal or cortical involvement preoperatively can not only compromise the primary ablative surgery but also drastically alter the plan for reconstruction.

In the immediate preoperative setting, clear and concise communication between surgeon and anesthesiologist is paramount for safe airway management. A retrospective review of 320 patients with cancer of the floor of the mouth by Shaha et al. attributed half of the postoperative mortalities to airway compromise. This underscores the importance of a coordinated approach between the anesthesiologist and the surgeon to provide the safest airway plan possible both at the time of initial induction and in the postoperative setting.

Approaching patient selection as a perfunctory preoperative exercise is a grave disservice to the patient. Such efforts risk poor oncologic control or compromised reconstruction. However, a diligent history and physical examination, along with a multidisciplinary approach toward surgical optimization, can position the patient for a successful surgical outcome.

History

1.
History of present illness
- a.
  Characterization of lesion: size, onset, growth, pain
- b.
  Complaint of an ill-fitting lower denture
- c.
  Assessment of speech, swallowing, and mastication
- d.
  Evidence of perineural invasion: immobility of the tongue, dysgeusia, numbness
- e.
  Screen for odynophagia, dysphagia, otalgia, oral bleeding
- f.
  Weight loss, malnutrition
- g.
  History of recent biopsy of an intraoral lesion
2.
Past medical history
- a.
  History of oral cavity leukoplakia, dysplasia, or lichen planus
- b.
  History of obstructive sleep apnea or cardiopulmonary disease
- c.
  History of radiation therapy
- d.
  History of cancer of the head and neck
- e.
  History of previous treatment to the area of the primary cancer, ipsilateral or contralateral neck
- f.
  History of immunosuppression
3.
Past surgical history
- a.
  History of surgical intervention of the oral cavity
- b.
  History of surgical intervention of the neck
- c.
  History of dental surgery
- d.
  History of mandibular fracture with reconstruction
- e.
  History of prior tracheostomy
4.
Family history
- a.
  History of difficulty with anesthesia
- b.
  History of bleeding diathesis
5.
Medications
- a.
  Anticoagulants
- b.
  Herbal products
- c.
  Immunosuppressants
- d.
  Allergies
6.
Social
- a.
  Alcohol
- b.
  Tobacco use
- c.
  Betel quid
- d.
  Review of occupational demands, particularly of those in the culinary industry, and of speech requirements
- e.
  Social support structure
- f.
  Jehovah’s Witness

Physical Examination

1.
General appearance
- a.
  Malnutrition, cachexia
  - 1)
    Present in 50% of head and neck cancer patients
  - 2)
    Independent predictor of survival
2.
Complete examination of the head and neck
- a.
  Oral cavity
  - 1)
    Observation
    - a)
      Exophytic
    - b)
      Deep infiltration
    - c)
      Ulcerations
    - d)
      Papillary
  - 2)
    Thorough assessment of the location and extent of the cancer
    - a)
      Proximity or invasion of intrinsic tongue musculature
      - i)
        Midline or unilateral
      - ii)
        Anterior or lateral
    - b)
      Assessment of tongue mobility
    - c)
      Diameter—measure for staging (e.g., T1–T4)
  - 3)
    Relationship between cancer margin and ductal papilla
  - 4)
    Dental evaluation, including evidence of carious or loose teeth
- b.
  Mandible
  - 1)
    Bimanual palpation of the cancer and mandible has been demonstrated to be superior to imaging in predicting cortical invasion.
  - 2)
    Proximity of cancer to the lingual surface of the mandibular periosteum
  - 3)
    Evidence of invasion through the mandibular cortex
  - 4)
    Evidence of cancer on the alveolar ridge or the buccal surface of the mandible
  - 5)
    Presence of a pathologic fracture
  - 6)
    Assess dimensions including mandibular height and anteroposterior thickness
  - 7)
    Involvement of the skin ( Fig. 30.2 )
  - 8)
    Presence of previous reconstruction/plating
- c.
  Cranial nerves
  - 1)
    Evidence of intraoral perineural invasion including
    - a)
      Mental nerve hypoesthesia
    - b)
      Numbness of the tongue
    - c)
      Dysgeusia
    - d)
      Impaired mobility of the tongue
  - 2)
    Complete assessment of cranial nerves II to XII
- d.
  Neck
  - 1)
    Palpation of both necks in the evaluation of nodal metastasis
  - 2)
    Postradiation skin changes, which may indicate the presence of neck fibrosis
  - 3)
    Previous neck incisions, which may indicate prior surgeries
- e.
  Evidence of synchronous primary ( Fig. 30.3 )
  - 1)
    Unilateral otitis media with effusion
  - 2)
    Stridor
  - 3)
    Dysphonia
3.
Potential donor site
- a.
  Fibula
- b.
  Radial forearm
- c.
  Supraclavicular region
- d.
  Pectoralis/anterior chest wall
4.
General physical examination
- a.
  Cardiovascular
- b.
  Pulmonary
- c.
  Mental

Imaging

1.
CT scan with contrast enhancement
- a.
  First-line examination with high reliability and ease of testing
- b.
  High-resolution, fine-cut, multiplanar CT to assess the integrity of the mandibular cortex
2.
MRI
- a.
  Improved soft tissue delineation
- b.
  Rarely indicated
3.
18-F-fludeoxyglucose positron emission tomography (18F-FDG PET CT)
- a.
  Reveals cervical metastasis
- b.
  Reveals distant metastasis
4.
Panorex
- a.
  Dentition
- b.
  Invasion of the mandible
5.
Chest CT
- a.
  Cardiopulmonary evaluation
- b.
  Pulmonary metastasis
- c.
  Second primary in the lungs
6.
18-F-fludeoxyglucose positron emission tomography (18F-FDG PET CT)
- a.
  More accurate at detecting metastatic lymph nodes and distant metastasis than either CT or MRI
- b.
  Unfortunately its high cost prohibits 18F-FDG PET CT from being a frontline screening tool.

Indications

1.
Wide local three-dimensional excision of soft tissue only; cancer not approaching or involving the mandible
2.
Marginal mandibulectomy
- a.
  Cancer involving mandibular periosteum but not invading cortex
- b.
  Cancer in close proximity to the mandibular periosteum with no evidence of bone invasion
- c.
  Cancer abutting healthy dentition without involvement of the periodontal ligament
3.
Segmental mandibulectomy
- a.
  Cancer invasion into the medullary matrix
- b.
  Cancer invasion to the occlusal surface of the mandible in an edentulous patient
- c.
  Edentulous patient with hypoplastic mandible with cancer that would otherwise meet criteria for marginal mandibulectomy
- d.
  Cancer abutting diseased dentition with involvement of the periodontal ligament
4.
Mandibulotomy
- a.
  Improved access to the anteriorly based cancer of the floor of the mouth

Contraindications

1.
Patient factors
- a.
  Medical comorbidities
2.
Marginal mandibulectomy
- a.
  Invasion of the mandible
- b.
  Gross invasion of bone marrow
- c.
  Cancer recurrence after radiation
- d.
  Hypoplastic mandible
- e.
  Planned remnant of bone less than 1 cm
3.
Segmental mandibulectomy
- a.
  To improve surgical exposure
4.
Mandibulotomy
- a.
  Atrophic mandible

Preoperative Preparation

1.
Consultations
- a.
  Anesthesia
- b.
  Reconstructive Surgeon
- c.
  Speech and Swallow Therapist
- d.
  Medical Oncologist
- e.
  Radiation Oncologist
- f.
  General surgeon if a feeding tube is anticipated
2.
Preoperative pathology
- a.
  Ultrasound-guided fine-needle aspiration of suspicious cervical lymph node
- b.
  Biopsy of primary lesion
- c.
  Independent institutional review of biopsy performed at an outside hospital
3.
Further preoperative preparation
- a.
  Panendoscopy—can be performed at the time of ablative surgery
- b.
  Extraction of carious teeth—may be extracted at time of ablative surgery
- c.
  Preoperative laboratory testing
  - 1)
    Nutrition
    - a)
      Gross abnormalities may delay surgery or restructure postoperative nutrition planning.
    - b)
      Albumin: surrogate marker of long-term nutritional status, half-life of 20 days
    - c)
      Prealbumin: surrogate marker of recent nutritional status, half-life of 8 days
  - 2)
    Hemoglobin/hematocrit:
    - a)
      If comorbidities such as anemia or significant cardiopulmonary history are present

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here