Excision of Cancer of the Floor of the Mouth
James W. Rocco
INTRODUCTION
Cancer of the oral cavity accounts for 5% of all cancers in the United States, with a significant proportion of these being squamous cell carcinoma of the floor of the mouth (FOM). A detailed history, physical examination, and preoperative biopsy are essential in establishing the diagnosis. The majority of these patients will have a history of tobacco and alcohol use. Clinical examination and preoperative imaging play a critical role in the diagnostic assessment, therapeutic planning, and successful management of these cancers. Operative techniques for the removal of these cancers are straightforward with early lesions usually being removed through a transoral approach. More advanced cancers often require alternate approaches and may involve partial resection of the ventral tongue or mandible to obtain adequate margins of resection. Close cooperation between the ablative and reconstructive efforts is essential in obtaining clear margins of resection while preserving speech and swallowing function.
HISTORY
A mass arising in the FOM is a common presenting complaint to the health care professional. Due to the wide variety of benign and malignant etiologies possible, a detailed history is the critical first step in patient evaluation (Table 2.1). A prior history of trauma, dental procedures, recent infection, mass or lesion since childhood, past surgery, or cancer may be a vital clue to the origin of the mass. A comprehensive discussion of risk factors for malignancy is also mandatory, and all patients should be queried in detail regarding tobacco and alcohol use, as well as prior radiation exposure, sexually transmitted diseases, and possible immune suppression.
The vast majority of malignant lesions presenting in the FOM are squamous cell carcinoma. In about 50% of these cases, the cancer will be limited to the FOM, although some patients will present with advanced stage cancer with metastasis to the neck. Often a patient will be referred to the otolaryngologist-head and neck surgeon after a dental examination identifies an asymptomatic mass in the early stages of disease. However, with more advanced cancer, it is not uncommon for the patient to present with bleeding, ulceration or pain, foul odor, obstruction of the submandibular duct, or a mass in the neck. In the case of squamous cell carcinoma, these patients are usually male, in the fifth to sixth decades of life, with a history of tobacco and alcohol use. There has also recently been increased awareness of the role of smokeless tobacco in the induction of squamous cell carcinoma of FOM specifically with chewing tobacco showing a relationship to verrucous carcinoma. In addition, outside of the United States such as in India and other areas of Southeast Asia, widespread use of the betel nut shows a strong correlation with FOM and buccal squamous cell cancer. The relationship between human papilloma virus (HPV) infection and oral cancer is not nearly as established and pronounced as for that found in the oropharynx.
The characteristic history of a cancer in the FOM is that of a slowly growing lesion, in some instances submucosal and painless and at other times ulcerated and tender. These lesions can arise in regions of
prior erythroplakia or leukoplakia. Patients often develop ulceration, bleeding, pain, and obstruction of the submandibular duct. The patient should also be questioned about changes in swallowing or articulation, weight loss, aspiration, cough, numbness of the tongue, or skin over the mandible. All of these could be a sign of deep infiltration into the muscular floor or mandible with impaired function as suggested by weakness of the hypoglossal nerve with restricted mobility of the tongue or numbness of the lingual or mental nerves. It is not unusual for cancers with deep muscle invasion to restrict tongue mobility with a subsequent change in both the quality of speech and ease of articulation, as well as a detrimental impact on swallowing function. Patients with far advanced cancers may present with destruction of the anterior segment of the mandible and invasion of the skin of the chin.
prior erythroplakia or leukoplakia. Patients often develop ulceration, bleeding, pain, and obstruction of the submandibular duct. The patient should also be questioned about changes in swallowing or articulation, weight loss, aspiration, cough, numbness of the tongue, or skin over the mandible. All of these could be a sign of deep infiltration into the muscular floor or mandible with impaired function as suggested by weakness of the hypoglossal nerve with restricted mobility of the tongue or numbness of the lingual or mental nerves. It is not unusual for cancers with deep muscle invasion to restrict tongue mobility with a subsequent change in both the quality of speech and ease of articulation, as well as a detrimental impact on swallowing function. Patients with far advanced cancers may present with destruction of the anterior segment of the mandible and invasion of the skin of the chin.
TABLE 2.1 Lesions Reported in the FOM | |||||||||||||||||||||
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PHYSICAL EXAMINATION
Cancer presenting in the FOM should be carefully inspected and the dimensions recorded in the preoperative assessment. It should be noted whether the cancer involves the mucosa or is only submucosal. Bimanual palpation should be used when feasible to determine the extent and depth of any lesion and whether it involves critical structures such as the deep tongue musculature, lingual surface of the mandible, or the ventral anterior tongue. Location of the cancer relative to Wharton ducts, whether it directly involves the ducts, and if the ducts are patent should also be noted. Palpation of the submandibular glands can often be used to express saliva from the ducts, and this technique should be performed on all lesions of the FOM. Specific deficits in the function of the lingual nerve should be evaluated. For those lesions involving or adherent to the lingual aspect of the mandible, care should be taken to note the quality and state of any dentition, whether there are any loose teeth, periodontal disease, and if there is any evidence of numbness in the distribution of the mental nerve bilaterally. For lesions extending deep into the tongue, the physical examination should specifically address the function of the hypoglossal nerve, including mobility of the tongue, as well as articulation and swallowing function. The skin of the chin should be inspected for signs of infiltration. Bimanual palpation can determine possible invasion into the sublingual glands, extension into the submandibular glands, or direct extension into the neck. The presence of a mass in the neck should also be noted. In patients with particularly large lesions that are painful, bleeding and friable, or exophytic, it may be necessary to defer a detailed physical examination until the patient is in the operating room. At the completion of the physical examination, the surgeon should have determined the true and precise extent of the lesion, proposed a definitive surgical approach, and considered different reconstructive options.
INDICATIONS
Surgery remains the most appropriate treatment for cancer of the FOM since radiation therapy is less effective oncologically and causes complications such as radiation caries and osteoradionecrosis of the mandible. The decision to perform surgery for cancer of the FOM is based on many factors including overall patient health, patient life expectancy, specific tumor pathology and behavior, tumor stage and expected morbidity of treatment, reconstructive options, and predicted treatment outcomes. A detailed history and physical, appropriate medical consultation, preoperative radiographic imaging, and intraoperative examination with biopsy followed by pathology evaluation and reconstructive consultation are critical in the proper selection of patients for surgery.
CONTRAINDICATIONS
Contraindications to surgery can be divided into local factors and patient comorbidities. With regard to local factors, the only significant absolute contraindication to surgery would be direct extent of a FOM cancer into the neck with carotid artery encasement or encasement of the carotid artery by metastatic lymph nodes. Relative contraindications include those patients in whom surgical excision, while technically feasible, precludes any significant quality of life in the setting of the patient’s wishes based on expected cure rates and associated surgical morbidity. For example, a large T4 FOM cancer requiring excision of facial skin, mandible, tongue, and larynx to achieve negative margins might be better served by a palliative regimen once the diagnosis is established. Distant metastases are a relative contraindication, since in many cases palliative surgical therapy can offer significant benefit by relieving pain and bleeding, eliminating the social isolation from necrotic or infected tumor, and allowing a return to an oral diet, long before distant metastasis ends the patient’s life. Patients with significant comorbidities such as dementia, advanced cardiovascular or pulmonary disease, or end-stage renal failure are probably best managed by nonsurgical means.
PREOPERATIVE PLANNING
Biopsy
Incisional biopsy or fine needle aspiration biopsy of FOM lesions are essential tools in the preoperative evaluation of a mass or an ulcer in the FOM. A punch biopsy in the office under local anesthesia followed by frozen section analysis can readily establish the diagnosis at the time of initial evaluation, potentially determine the depth of invasion, and ensure that other critical preoperative planning occurs in the setting of known tumor pathology. In the case of submucosal lesions, which may represent nonmalignant or nonsquamous malignant etiologies, fine needle aspiration can be particularly valuable in establishing a rapid diagnosis and assisting in preoperative therapeutic planning.
Imaging Studies
Imaging studies are mandatory in the preoperative evaluation of a mass in the FOM. Proper imaging provides valuable information regarding the three-dimensional extent of the mass and potential involvement of critical regional structures such as the deep tongue musculature or mandible, identifies direct extension into the submandibular glands or soft tissues of the neck, and can readily identify cervical lymphadenopathy.
A computed tomography (CT) scan of the neck with contrast is a good first choice for a preoperative planning study. In those cases where office or operating room examination is suspicious for invasion of the mandible, a dedicated CT of the mandible (no contrast with bone windows) can also be performed to identify irregularities or erosion of the cortex, as well as to determine the extent of involvement of the mandible to facilitate preoperative surgical and reconstructive planning. If the lesion is poorly defined on CT scan or hidden by extensive dental artifacts, or there is concern for invasion of the deep tongue muscle or direct extension into the neck, a magnetic resonance imaging with contrast is particularly useful in defining the extent of the lesion and potential involvement of critical vasculature structures such as the carotid artery. Routine positron emission tomography scans are not recommended in the preoperative evaluation of lesions of the FOM. However, in the case of malignant tumors, they can aid in demonstrating distant metastases, potentially altering the therapeutic plan.
Preoperative Dental Evaluation
Poor oral hygiene is found in many patients with cancer in the FOM. Consequently, it is necessary that preoperative dental evaluation and appropriate dental care be provided. This is especially important for patients who will receive postoperative radiotherapy. In this setting, it is important that the patient has appropriate
dental prophylaxis, which often consists of restoration or dental extraction, and fluoride for the prevention of radiation caries of the remaining teeth. Teeth within or near the tumor should be extracted at the time of surgical excision.
dental prophylaxis, which often consists of restoration or dental extraction, and fluoride for the prevention of radiation caries of the remaining teeth. Teeth within or near the tumor should be extracted at the time of surgical excision.
Comorbidities
Medical comorbidities are common in patients with cancer of the head and neck and can have a significant impact on the outcome of surgical therapy and may even preclude curative therapy as an option. The potential impact of medical comorbidities should be minimized through proper identification in the preoperative evaluation followed by appropriate referral and subsequent medical management to optimize the surgical candidate’s health status. Patients with significant comorbidities should be seen by a medical specialist who concentrates on the perioperative medical care of the surgical patient. Special consideration should be given to patients with congestive heart disease, cardiac arrhythmia, peripheral vascular disease, pulmonary disease, renal disease, and other cancers.
Management of anticoagulation in the perioperative period is constantly evolving, and surgeons should access ACCP guidelines for the most current clinical practice guidelines. In general, patients on warfarin/Coumadin should temporarily stop therapy 5 days before surgery and resume it 12 to 24 hours after surgery, assuming adequate hemostasis was achieved and there is no active bleeding. Patients at high risk for thromboembolism should receive bridging anticoagulation therapy that can consist of intravenous unfractionated heparin that should be stopped 4 to 6 hours before surgery, or low molecular weight heparin that should be stopped 24 hours before surgery.
Speech and Swallowing Evaluation
Patients with a cancer of the FOM often demonstrate significant functional impairment in speech and swallowing function at presentation that becomes worse after surgical therapy. In addition to problems with speech, these patients can experience significant difficulties with the oral stage of swallowing. Fortunately, the potentially life-threatening complication of aspiration is uncommon in these lesions. Preoperative assessment and aggressive speech and swallowing therapy in the postoperative setting can establish realistic expectations and help the patient maximize speech and swallowing function after treatment.
Airway Management
The time to plan surgical airway management is in the preoperative setting and requires a clear discussion between the surgeon and the anesthesia staff. Many lesions of the FOM are small and present no significant airway challenges other than the need for nasotracheal intubation to allow adequate exposure for resection at the time of surgery. However, even small lesions of the FOM that are reconstructed using a skin graft and bolster may result in a challenging postoperative airway and ultimately require tracheostomy for airway stability and tracheobronchial toilet, until the bolster is removed. More extensive lesions of the FOM with tongue or mandible involvement often require fiberoptic intubation followed by tracheostomy after intubation or awake tracheostomy to provide a stable and safe airway during surgery and the postoperative period. The majority of patients undergoing microvascular free-flap reconstruction require a tracheostomy for airway stability in the postoperative period.
Informed Consent
Due to the complexity of the FOM, its proximity to critical structures, functional role in speech and swallowing, and impact on appearance, surgery on the FOM requires a detailed preoperative discussion to achieve informed consent. Patients should be advised on issues common to all surgeries as well as those specific to the FOM operative site. The surgeon should carefully describe likely outcomes, as well as potential complications and their consequences. At a minimum, potential for wound breakdown or fistula, nerve injury or sacrifice and their sequelae and chance for recovery, need for further surgery, impact of a positive or close margin, expected changes in speech and swallowing function, mandible nonunion or fracture, and dental loss must be discussed.
