Malignant Tumors of the Floor of the Mouth 

Updated: Jul 17, 2018
Author: Ethem Guneren, MD; Chief Editor: Arlen D Meyers, MD, MBA 

Overview

Background

The oral cavity is the primary site of verbal human communication. It has many additional important functional roles, including bolus preparation and formation, taste, and deglutition. Oral cavity cancer treatment, particularly for advanced tumors (because of radical surgery), destroys the integrity of this area. Extensive reconstructive efforts are required to maintain oral continuity, to facilitate swallowing, to prevent aspiration, and to preserve satisfactory speech. Further, proper planning is necessary to hopefully gain a satisfactory reconstruction in a single stage. In addition, adequate tongue mobility and oral sealing with adequate sensory innervation are required.

See the image below.

Early oral squamous cell carcinoma in the buccal m Early oral squamous cell carcinoma in the buccal mucosa arising from a chronic candidal leukoplakia in a person who smokes heavily. The lesion was a painless, chronic indurated lump.

Problem

Cancer of the floor of the mouth can have devastating sequelae. It usually begins as a small asymptomatic nodular or ulcerative lesion, which may be overlooked. Because of its nature, ie, a painless lesion usually located in a hidden area, many patients are diagnosed at an advanced stage, when the lesion becomes painful or causes functional impairment.

Epidemiology

Frequency

Head and neck cancers constitute 15% of all cancers of the body, with an incidence of 9.5 cases per 100,000 in the general population. Malignant tumors of the oral cavity account for approximately 30% of all head and neck cancers and for 5% of all cancers in the United States. Cancer of the floor of the mouth accounts for 28-35% of all oral cancers.

The worldwide incidence varies greatly. Although cancer of the floor of the mouth accounts for 5% of all cancers in the United States, it accounts for 50% of all cancers in India. This difference is the result of cultural variations and habits (eg, excellent oral hygiene in the United States and betel chewing in India).

Oral cavity cancers are more common in males, with a male-to-female ratio of 3-4:1.

Although malignant tumors of the floor of the mouth develop most commonly after the fifth decade of life, they are not uncommon in younger persons.

Etiology

Tobacco and alcohol have additive effects on oral cancer. Tobacco includes smokeless tobacco derivatives, such as snuff and betel nut.

In India, tobacco is blended with slaked lime and rolled in a betel nut leaf to form a quid, which is called a pan. A common practice is to hold the pan against the buccal mucosa for prolonged periods, leading to a mild euphoric state. The prolonged and repeated exposure of the oral mucosa to tobacco smoke, alcohol, and other irritants has been proposed as a principal cause of cancer. Smoking and alcohol consumption have a linear dose-specific relationship with oral cancer.

The consumption of 40 or more tobacco cigarettes and 7 or more ounces of alcohol per day increases the incidence of oral cancer to 3-5 times that in controls. The addition of poor oral hygiene and poor dentition can increase the risk 8-fold.

Some people seem to be more vulnerable than others to the effect of these irritants. The nature of the increased vulnerability may be genetic, familial, or acquired (eg, immunosuppression, syphilis, Plummer-Vinson syndrome, chronic candidiasis). These risk factors and the underlying pathogenesis do not disappear following surgical excision or radiation therapy for the cancer. The organs remain susceptible. If the patient continues to drink, smoke, and be exposed to other irritants, the risk of developing a second primary cancer increases to 15% within 5 years and increases to 40% thereafter. In addition, the rate of recurrence increases and the response to radiotherapy decreases.

Pathophysiology

The head and neck region has rich vascularity, which is an advantage for treating cancer in this region. In addition, this vascularity increases the metastasis. The shells of tumors that metastasize to the head and neck are richer in vascularity than the tumor tissue itself.

Presentation

The most common presentation of cancer of the floor of the mouth is a painless inflamed superficial ulcer with poorly defined margins. Preexistent or coincident leukoplakia can be observed in adjacent tissues in approximately 20% of cases. The presence of erythroplasia strongly suggests an invasive tumor. A small ulceration or nodular lesion may remain asymptomatic for long periods, so the patient may not seek medical attention. Vague symptoms of soreness in the regional mucosa could be attributed to an aphthous ulcer. In fewer than 50% of cases, the ulcer is localized only to the floor of the mouth on initial presentation. If the tumor has grown with relatively few symptoms or if the patient has neglected its initial signs, the patient may first present with a neck mass, by which time the tumor has metastasized.

Malignant tumors of the oral cavity grow rapidly, with frequent and early metastasis to the surrounding regional lymph nodes. Compared with the corresponding T categories, high T levels are more prone to metastasis. The incidence of regional nodal metastases at the time of initial clinical evaluation is 30-35%. Clinical symptoms are caused by growth of the lesion and invasion of deeper structures. The edges become more indistinct, and the base of the tongue and the lingual aspect of the alveolus may become involved. Referred pain to the ear (through the lingual nerve), halitosis, evidence of regional lymph node involvement, and bleeding are signs of advanced disease.

A systematic examination includes inspection of teeth; labial, buccal, and gingival mucosae; tongue; and palate. The floor of the mouth is carefully examined using a tongue depressor to retract the tongue. Then, the floor of the mouth and cheek is bimanually palpated with a glove-lined finger to assess location, size, and extent of the primary tumor. Bimanual examination also allows assessment of the involvement of the structures of the submandibular triangle. The head and neck examination is completed with a direct examination of the ears, nose, and oropharynx and palpation of the neck.

The dentoalveolar structures are assessed for the presence of gingival disease and the need for dental repair. If needed, the patient is referred to a dentist for treatment in order to minimize complications during surgery or radiation therapy. Close inspection of the external ears, the external auditory canal, and the tympanic membranes is then required. Exclude ear pathology in the differential diagnosis for referred otalgia.

Squamous cell carcinoma spreads through the regional lymphatics. The primary lymphatic drainage of the mouth floor filters through the submandibular and submental lymph nodes (level I) and upper anterior cervical (jugulodigastric) node groups (level II). Examination of the neck should include both sides and all cervical triangles to detect regional lymphadenopathy. As described above, the submandibular triangles are palpated bimanually with a glove-lined finger.

Indications

Selection of the treatment modality is based on an assessment of the patient's individual needs and the clinical judgment and experience of the physicians. Surgical resection or radiation therapy is usually effective in the treatment of stages I and II cancers. Either of these modalities alone is usually insufficient for stages III and IV cancers. Therefore, in most cases, a combination of the 2 modalities should be considered for the proper treatment of advanced cancers.

Chemotherapy should also be considered in the management of large tumors when its addition may improve the results in organ-sparing protocols. To diminish the size of the lesion for a convenient operation, preoperative radiation therapy and neoadjuvant chemotherapy are considered in the treatment of huge masses. In any case, primary tumors should be treated radically, with a careful evaluation of the neck nodes.

Relevant Anatomy

The floor of the mouth is a horseshoe-shaped hollow anatomic site of the oral cavity. It extends from the anterior inner aspect (lingual surface) of the lower gingiva and alveolar ridge of the mandible laterally to the insertion of the anterior tonsillar pillar into the tongue. It is medially bounded by the free inferior surface of the tongue. Its concavity is crucial for efficient swallowing of saliva.

Anteriorly, it is divided into 2 halves by the lingual frenulum. Additionally, the papillae sublingualis and plica sublingualis are located in this concave region, which is covered by a mucous membrane with stratified squamous epithelium. Two major salivary glands are under the mucosa. Sublingual and submandibular glands drain into the floor of the mouth via the Bartholin duct and the Wharton ducts, respectively. The latter is about 5 cm long and courses between the sublingual gland and the genioglossus muscle. Its orifice is in the anterior floor of the mouth near the midline on the papillae sublingualis. On the midline, genioglossus and geniohyoid muscles separate the sublingual glands. The sublingual gland has several minor openings in addition to the Bartholin duct on the plica sublingualis.

The sublingual veins are under the pink and transparent mucosa. The genioglossus muscle, geniohyoid muscle, mylohyoid muscle, and the anterior belly of the digastric muscle form the muscular diaphragm of the mouth floor. The lingual nerve, a branch of the posterior trunk of the mandibular division of the trigeminal nerve, provides sensation to the floor of the mouth. The arterial supply comes from the lingual artery, a branch of the external carotid. The regional lymphatics (level I) include the submandibular and submental lymph nodes, which lie inferior and lateral to the mylohyoid muscle in proximity to the submandibular gland.

Contraindications

The use of radiation therapy as a primary modality may be contraindicated in tumor beds that have been previously irradiated, in tumors with mandibular involvement, and in areas with a history of poor wound healing.

Quality of life is the most important goal. Consider reconstruction for all patients who undergo resections of the mouth floor for cancer unless a major contraindication for general anesthesia exists. A poor prognosis does not necessarily exclude a patient from reconstruction, although it may influence the techniques used. The more sophisticated reconstructive surgeries, such as a composite free flap, can also be performed in conjunction with radical resection.

 

Workup

Laboratory Studies

See the list below:

  • For systematic evaluation of the patient, obtain the following laboratory studies:

    • A complete blood cell count is needed. This test is used to assess the risk for anemia or infection and rule out metabolic anomalies; include measurements of electrolytes and kidney function, especially if patient is receiving diuretics.

    • Liver function studies are necessary if the patient has significant risk of liver damage due to alcoholism or a history of hepatitis.

    • Bleeding and clotting tests and urinalysis are needed because these patients are candidates for surgery.

    • Type and cross blood are set aside for transfusion in patients at high risk of significant blood loss.

Imaging Studies

See the list below:

  • Obtain a plain radiograph to complete the systematic evaluation of the patient to rule out the presence of metastasis to the chest or other cardiopulmonary disease.[1]

  • Plain anteroposterior and lateral cranial radiography and Waters roentgenography are routine.

  • Mandibular orthopantomography (Panorex), CT scanning, and MRI are indicated for large tumors to evaluate the inner cortical periosteum and bone invasion of the mandible and in cases with clinically positive neck involvement.

  • MRI is more reliable than CT scanning in revealing metastatic nodal disease and extracapsular spread of tumor in lymph nodes smaller than 2 cm in diameter. Tissue characterization with MRI is superior to that with CT scanning. The integrity of cortical bone (mandible) is more accurately assessed with CT scanning, and the integrity of medullary bone (mandible) is more accurately assessed with MRI.

Other Tests

Occasionally, a lesion in the oral cavity appears indistinct and may not be readily visualized on inspection. In these cases, toluidine blue dye can be applied to delineate the area of involvement more clearly.

Toluidine blue stains the nucleus of cells in an area of ulceration but not in areas of intact normal mucosa. The dye is not specific for malignant cells, but it stains areas of ulceration with increased cell turnover or with aberrant cells. The technique is also useful in staining the mucosa of individuals with suspected field cancerization in order to select suspicious sites for biopsy.

Diagnostic Procedures

The examination is completed with endoscopies of the upper respiratory and upper gastrointestinal systems.

Swelling of the floor of the mouth is sometimes difficult to diagnose clinically. With a submandibular mass, gland enlargement due to lithiasis may be difficult to differentiate from duct obstruction and nodal enlargement due to tumor metastasis, in which case plain radiography and CT scanning would not be helpful. In these circumstances, fine-needle aspiration biopsy is necessary. The accuracy of fine-needle aspiration results depends largely on the pathologist's experience with cytologic interpretation, the quality of the specimen submitted, and the proficiency of the person who performs the biopsy. In difficult cases, the use of ultrasonographically assisted fine-needle aspiration is very helpful.

An excisional biopsy should be performed for a small lesion. For deeper and more extensive lesions, an incisional biopsy including healthy tissue margins and adequate tissue samples should be performed.

Sentinel lymph node biopsy is a new technique in staging the clinically N0 (see Staging) neck. Sentinel lymph node evaluation in head and neck squamous cell carcinoma provides a highly accurate staging of N0 necks in oral and particularly in oropharyngeal carcinomas.[2] Lymph node mapping is performed with preoperative lymphoscintigraphy and intraoperative use of a hand-held gamma probe. Tc 99m–labeled nanocolloids are injected around the primary tumor. The sentinel lymph node (identified with dynamic scintigraphy) and the neck dissection specimen are sent separately for histological analysis. The sentinel lymph node and the neck dissection specimen are then assessed for occult metastasis and compared.

Histologic Findings

Squamous cell carcinomas account for more than 90% of oral cancers. Adenocarcinomas are second in frequency. Other tumors include malignancies of the minor salivary glands, including mucoepidermoid and adenoid cystic carcinoma, melanoma, lymphoma, sarcoma, basaloid squamous carcinoma, and very rarely, malignant hemangiopericytoma.

Typically, squamous carcinoma is an ulcerated lesion with indurated edges. It may project from the surface (exophytic) or infiltrate deeply (endophytic). Verrucous carcinoma is a particular lesion that is raised above the surface, having multiple papillae. In the past, it was classified according to pleomorphism and mitosis of the lesion, but this grading is subjective and is of limited value.

Staging

After the diagnosis of cancer is pathologically proven, diagnostic staging is based on the clinical evaluation with measurable size of the lesion. It includes information obtained from CT scanning or MRI. Staging occurs before any definitive therapy is instituted. The staging system allows the surgeon to classify a patient in such a way that appropriate therapy can be selected.

The staging systems of the American Joint Committee for Cancer (AJCC) and the International Union Against Cancer (UICC) and end-results reporting are the standard means of describing tumor extent for carcinomas of the oral cavity. The uniformly accepted staging system is the tumor node metastasis (TNM) system. It is a composite of the primary tumor and nodal and systemic metastases substages.[3]

  • T represents the size and extent of the primary tumor.

    • T - Preinvasive cancer (carcinoma in situ)

    • T1 - Tumor of 2 cm or less in greatest dimension

    • T2 - Tumor of more than 2 cm but not more than 4 cm

    • T3 - Tumor of more than 4 cm in greatest dimension

    • T4 - Massive tumor of more than 4 cm in diameter with invasion of the base of the tongue or invasion of the mandible

  • N represents the state of regional lymph node involvement.

    • N0 - No clinical evidence of regional lymph node involvement

    • N1 - Evidence of involvement of single movable homolateral node less than 3 cm in greatest dimension

    • N2 - Evidence of involvement of a single ipsilateral lymph node more than 3 cm but not more than 6 cm in greatest dimension or involvement of multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension, or involvement of bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension

      • N2a - Evidence of involvement of a single ipsilateral lymph node, more than 3 cm but not more than 6 cm in greatest dimension

      • N2b - Evidence of involvement of multiple ipsilateral lymph nodes, none more than 6 cm in greatest dimension

      • N2c - Evidence of involvement of bilateral or contralateral lymph nodes, none more than 6 cm in greatest dimension

    • N3 - Evidence of involvement of any fixed regional lymph node or multiple movable regional nodes, one more than 6 cm in greatest dimension

  • M represents the presence of distant metastases.

    • M0 - No clinical evidence of distant metastases

    • M1 - Evidence of distant metastases

  • Stages according to the TNM system are as follows:

    • S1 - T1/N0/M0

    • S2 - T2/N0/M0

    • S3 - T3/N0/M0; T1 or T2 or T3/N1/MO

    • S4 - T4/N0 or N1/M0; any T/N2 or N3/M0; any T/any N/M1

 

Treatment

Medical Therapy

Various therapeutic measures are available for managing localized carcinomas of the oral cavity, including surgical excision, radiation therapy, electrodesiccation, cryotherapy, laser-beam excision, chemotherapy, and a combination of these methods. Individualized treatment depends on the anatomic site, size, and extent of the primary lesion; the presence or absence of metastatic disease in the neck; the patient's age and general medical health; morbidity associated with the treatment program; experience and skill of the surgeon and the radiation oncologist; and the wishes of the patient.

Although many currently experimental regimens of chemotherapy are being tested in the quest for improved outcomes, no uniformly established chemotherapy protocol for the primary treatment of oral cancers presently exists. On the other hand, as an adjuvant therapy in treating massive or potentially unresectable tumors, chemotherapy has a definite role. If a patient is pretreated with chemotherapy (ie, neoadjuvant or induction adjuvant therapy), the tumor size is often reduced to the point that surgical ablation of the tumor is feasible. Following primary treatment of cancer with surgery or radiation therapy, consolidation chemotherapy has a particular role in the completion of advanced cancer treatment.

When the tumor is small or is limited to the mucosa, it is highly curable with irradiation alone. Therefore, radiation therapy should be the first choice for treatment. Radiation therapy for small lesions consists of external-beam therapy with various boost techniques (interstitial implant or intraoral cone). For moderately advanced or exophytic lesions, a trial course of radiation therapy may be administered first, and salvage surgery is used for any residual disease at the primary site or neck nodes. If the tumor is thicker than 2 mm, a staging lymphadenectomy, followed by radiotherapy for those with involved nodes or prophylactic neck irradiation for all in this group, is suggested. For advanced lesions, a combined therapy of surgery and radiation is the suggested treatment.

A study by Kobayashi et al indicated that in patients with advanced cancer of the tongue and floor of the mouth, treatment with superselective intra-arterial chemoradiotherapy (SSIACRT) is an effective alternative to either surgery or surgery with postoperative radiation therapy. The study, which included 62 patients with stage III or IV squamous cell carcinoma, found that patients reported a higher quality of life following SSIACRT than they did after the other two treatments, while the 5-year disease-specific survival rate for SSIACRT was 83.2%, compared with 92.9% and 62.9% for surgery and surgery followed by radiation therapy, respectively.[4]

Surgical Therapy

Small lesions are treated most conveniently with surgical excision. The small defect is reconstructed with direct closure or skin grafting or is allowed to heal spontaneously. If a defect can be closed directly, especially when the alveolus has been sacrificed, reconstruction can be rapid and free of complication. In many areas, floor-of-the-mouth defects without exposure of bone and buccal mucosa can be reconstructed with split-thickness skin grafts. Tie-over dressings are messy; therefore, the quilting technique is recommended, with stab drainage incisions of the graft between the quilting sutures.

Relatively larger defects can be reconstructed easily with local flaps, such as buccal mucosa, tongue, palate, and nasolabial flaps.[5] The pedicles are divided at 10-14 days. If teeth are present, bite blocks are inserted to prevent premature pedicle division. To further ensure tongue mobility following occurrence of any raw area on the undersurface of the tongue, it is resurfaced with a quilted split-thickness skin graft. Otherwise, scarring pulls the tongue forward.

For larger defects, the most reliable distant flaps include the deltopectoral flap and the pectoralis major myocutaneous flap. The latter is good for providing bulk, especially following large resections of tongue. It could also carry a rib segment to the defect of mandible.

T3 and T4 lesions require a lip-split cheek-flap procedure for exposure. Usually, the base of the tongue and a portion of the mandible (partial or segment) are also excised. Maintenance of the lower border of the mandible or immediate osseous reconstruction with a composite free flap greatly diminishes the aesthetic and functional defect following these resections, especially in the midline. Free tissue transfer has replaced most of the techniques. Many flaps have been used for lining. The most reliable include the radial forearm flap, ulnar forearm flap, scapular flap, lateral arm flap, and dorsalis pedis flap. If a cheek flap is being used, proceeding with an incontinuity neck dissection is convenient.

Management of a patient with head and neck cancer who has N0 stage neck involvement is controversial. Waiting and watching may be suitable for carefully selected patients. On the other hand, bilateral supraomohyoid dissection should be considered for the treatment of primary site lymphatic channels and for accurate staging in patients with N0 neck involvement. Neck involvement is the most important prognostic factor and decreases the survival rate. Necks with unilateral N+ involvement are treated with an ipsilateral therapeutic neck dissection. Necks with bilateral N+ involvement are treated with a bilateral therapeutic neck dissection.

Preoperative Details

Complete a thorough history, physical examination, tissue diagnosis confirmation, lesion extent determination, and operative plan. The patient's expectations should be well understood, and the patient must be well informed by the surgeon about early and late postoperative possible outcomes. In order to decrease the possibility of infection and to facilitate wound healing in patients with poor oral hygiene or dentition, a dentist should be consulted and intense oral care should be performed before surgery.

Intraoperative Details

In rare circumstances (eg, biopsy), a local anesthesia can be used. A lingual block adequately anesthetizes the hemitongue and floor of the mouth. General endotracheal anesthesia is used. The use of a nasal intubation is preferable because it allows greater unrestricted access to the oral cavity. To manage larger tumors, a tracheostomy should be considered because edema of the tissues of the oropharynx may lead to postoperative airway compromise. A tracheostomy also facilitates unrestricted access to the oral cavity. The patient is paralyzed to allow for adequate mouth opening and tongue manipulation. Appropriate prophylactic antibiotics and a steroid bolus are administered at the start of the operation. Foley catheterization is performed if the procedure is expected to last longer than 2 hours.

The patient is positioned on a Mayfield headrest with 15-20° of head elevation. Using a standard operating room table and extending the patient's neck with proper head support with a headrest and shoulder rolls is also practical. The mouth gag is inserted, and posterior packing is performed. Using the coagulation current or knife, the mucosa is incised with care to include a 1- to 2-cm margin of surrounding healthy tissue. Silk suture 2/0 is placed through the anterior margin of resection, and the circulating nurse is instructed to mark this on the pathology form. The inferior margin of resection for superficial cancers is deep to sublingual glands. The Wharton duct is transected while dissecting the deep margin of resection. After ensuring meticulous hemostasis and changing gowns and gloves, the wound is closed with split-thickness skin graft application.

Large tumors are approached using a lip-splitting incision or using a visor flap, which is carried out by incising the lower gingival buccal sulcus along the mandible. The periosteum is then undermined, and the skin of the chin and lower lip is elevated. The tumor is then excised conveniently. If any bony resection is necessary, the mandibulotomies are performed first and en bloc resection follows.

The surgical margins are evaluated at the time of excision. The specimens from the tumor surgical wound are submitted for frozen sections, and reconstruction is not planned until negative results are returned.

Postoperative Details

Postoperative care varies according to the extent of surgery. For primary reconstruction, oral care is sufficient. For any flap reconstruction, monitoring the patient and whole blood counts are needed. Maintain nutrition with a nasogastric tube until decannulation of the patient and monitor care of skin grafts, flaps, and oral hygiene. Infection and fistula formation are always possible following multilayer reconstruction.

Hematoma and hemorrhage can develop. Sufficient drainage and obliteration of dead space without tension is paramount to avoid this problem. Careful external dressing, no compression on the vascular pedicles of used flaps, and continued antibiotic therapy for at least 5-7 days are helpful.

Follow-up

The functional morbidity relating to deglutition and speech articulation varies based on the extent of the ablation and with the method of reconstruction. The most important decision is whether additional treatment is required according to the histopathologic examination of the excised specimen.

For excellent patient education resources, visit eMedicineHealth's Cancer Center. Also, see eMedicineHealth's patient education article Cancer of the Mouth and Throat.

Complications

Radiation therapy complications

Virtually all patients experience xerostomia if a substantial part of the parotid and submandibular glands is included within the radiation portal. Aside from the discomfort associated with the sensation of dryness, xerostomia makes chewing and swallowing food more difficult. Artificial saliva improves the comfort level of some patients. Others simply carry a small bottle of water around and rinse their mouth at frequent intervals. Other patients find that chewing gum specially formulated for dry mouths is helpful. Rinsing with a solution of baking soda in water is relatively bland and soothing and helps dissolve sticky saliva. The oral cholinergic agonists pilocarpine hydrochloride (Salagen) and cevimeline (Evoxac) in the management of xerostomia have shown encouraging results. Because the dry mouth is prone to opportunistic attack, patients may need specific therapy for fungal, viral, or bacterial infections.

Radiation therapy frequently alters the sense of taste.

Pain, generally secondary to mucositis, is common by the midpoint of treatment. For mild pain, simple analgesics (eg, aspirin crushed and dissolved in water, Aspergum) provide relief. For more severe pain, stronger measures are required. Viscous Xylocaine often provides effective pain relief, but patients tend to experience a burning sensation as the medication takes effect.

As treatment progresses, a patient’s nutritive needs are often not met. Patients require nutritional counseling and encouragement. Most patients tolerate 6 half-size meals per day, which is better than 3 full meals. Nutritional supplements between meals should be considered. When alterations of diet and blending of food are insufficient to permit the patient to ingest an adequate diet, nasogastric tube feeding or percutaneous gastrostomy placement provides alternative means of supporting the patient's nutritional requirements during radiation therapy.

Although patients who are edentulous may have more difficulty chewing their food during treatment, they are at a relative advantage in having a lesser risk of osteonecrosis. Having all patients undergo dental evaluation before radiation therapy is instituted can greatly eliminate this difference.

Failure to protect teeth from the changes produced by radiation therapy leads to dental decay that characteristically develops along the gum line. Even when decay is relatively advanced, appropriate intervention and restoration is worthwhile and can salvage the teeth. Aside from its salutary effect on the patient's appearance, restoration removes one portal of entry for infection that may lead to osteonecrosis. On the other hand, dental manipulation, by itself, may be sufficiently traumatic to produce osteonecrosis in previously marginally viable mandibular bone. Prevention of decay, therefore, is preferable. If, despite all efforts, osteonecrosis does develop, antibiotic therapy and patience should comprise the first line of management. Only when osteonecrosis is progressive or persistent should surgical management be undertaken.

Radiation therapy takes considerably longer than surgery to complete, but radiation therapy generally preserves both the anatomy and function of most irradiated tissues.

Surgical therapy complications

Complications include those of any surgical procedure (eg, infection, hematoma, skin necrosis, flap failure, wound breakdown). Insufficient coverage of intraoral structures, especially a reconstructed bone segment, is a major complication. Bony reconstruction complications, such as contour irregularities, resorption of bone, and osteomyelitis due to contamination of saliva, are also noteworthy. In this anatomic area, a salivary fistula may also develop and be difficult to treat in the patient who is irradiated.

The incidence of complications increases during a simultaneous neck dissection. If the carotid artery is exposed in the wound, especially if it is bathed in saliva and previous irradiation has occurred, catastrophic hemorrhage is a considerable risk. Immediately covering the artery with a muscle flap is advocated and may be performed prophylactically during the neck dissection.

Outcome and Prognosis

Resection of intraoral tumors may significantly affect appearance and function. It can result in significant tongue tethering that interferes with speech and swallowing. Mandibular resection causes chewing problems and, if it is in the symphyseal area, drooling and an Andy Gump deformity result. Lip resection may also cause drooling and speech articulation disorders. However, direct suturing is preferable for small defects.

The most important factors that determine the treatment and prognosis include tumor size, penetration depth, and evidence of regional lymph node involvement.

The overall 5-year survival rates in patients with cancers of the floor of the mouth range from 30-60%. The 5-year survival rate is more than 90% in stage I, 50-75% in stage II, and 25-40% in stage III and IV diseases. A retrospective study of 64 patients with stage III or IV squamous cell carcinoma of the tongue and floor of the mouth found the overall 5- and 22-year survival rates to be 34.4% and 6.3%, respectively.[6]

A study by Saggi et al using information from the Surveillance, Epidemiology, and End Results (SEER) Program database reported that for patients with floor of the mouth squamous cell carcinoma, 5-year overall survival (OS) and disease-specific survival (DSS) rates were 39% and 59%, respectively, with multivariate analysis revealing that determinants of OS and DSS included patient age; tumor grade, stage at presentation, and size; and surgery.[7]

A study by Zirk et al indicated that in patients with floor of the mouth squamous cell carcinoma, lymph node ratio (LNR) independently predicts OS. The investigators reported that in univariate analysis of patients with an LNR of 0.07 or below, the 5-year OS rate was 85%, compared with 25% for those with an LNR above 0.07.[8]

Distant metastasis develops rarely and relatively late in the development of carcinomas of the oral cavity. The risk of distant disease is best predicted based on the degree of lymphatic involvement because spread into the bloodstream occurs only after the lymphatic channels are invaded. Patients who have no clinically appreciable adenopathy rarely develop distant metastasis as their first sign of treatment failure. If distant metastasis develops, the lungs and bones are the most commonly affected sites for squamous carcinomas.

A study by Lanzer et al indicated that patients with squamous cell carcinoma of the floor of the mouth or tongue do not benefit from preservation of the ipsilateral submandibular gland during neck dissection. In a retrospective study of 168 patients, the investigators found, during a follow-up period of 3 or more years, that in patients with squamous cell carcinoma of the floor of the mouth or tongue, the rate of survival without lymph node recurrence was greatly influenced by whether or not the submandibular gland was excised, with the rate being just 28.5% in those in whom the gland was preserved. The study also found, however, that preservation of the submandibular gland did not influence the rate of lymph-node-recurrence-free survival in patients with squamous cell carcinoma elsewhere in the oral cavity or oropharyngeal region.[9]

Future and Controversies

Reconstructing complex defects often necessitates sophisticated techniques, and judgment is required for selection. In general, reconstruction is best performed at the time of the extirpation. Functional outcomes are mostly determined based on reinnervation and the extent of used flaps. Essential goals include the restoration of swallowing, intelligible speech, prevention of drooling, and the avoidance of salivary fistulas. Moreover, an acceptable aesthetic result must be achieved, if possible.

Ongoing investigations on some chemicals, such as lactoferrin and transforming growth factor–beta1 (TGF-beta1), suggest that the use of those materials as a primary or adjuvant chemotherapeutic agent may be effective.[10] Most recently, genetic aberrations of some cell cycle–regulatory genes have been reported in end-stage squamous cell carcinoma of the head and neck. Further studies on cell proliferation and tumor suppressor gene expression models are needed.