Malignant Tumors of the Floor of the Mouth Treatment & Management

Updated: Mar 01, 2016
  • Author: Ethem Guneren, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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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]

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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.

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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.

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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.

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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.

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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.

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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.

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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]

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. [7]

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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. [8] 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.

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