Tongue cancers account for over 25% of oral cavity SCCs and most commonly arise in the oral portion or anterior two-thirds of the tongue on the lateral edge or ventral surface. Infiltration of the underlying tongue musculature occurs early. The intrinsic tongue muscles are loosely arranged and endowed with a rich vascular and lymphatic supply, which may explain the high rate of regional metastases. Prognosis is directly related to the degree of infiltration and the presence of regional metastases. The biologic aggressiveness of small (< 4 cm) tongue cancers is noteworthy and is reflected in higher rates of occult regional metastases than those of similarly staged lesions arising from other oral sites. Occult nodal metastases are present in 30% to 40% of early lesions. Approximately 40% of patients have clinical evidence of node metastases at diagnosis. Primary-echelon node drainage is to the upper deep cervical lymphatics; however, involvement of middle and lower neck nodes (levels III and IV) is not uncommon. Bilateral nodal involvement can occur with cancers of the tip or the midline of the tongue. Locoregional recurrence in patients with tongue cancer accounts for 60% to 70% of cancer deaths. Distant metastases account for 15% of deaths, and second primaries account for 20% to 40%.
The management of carcinomas of the tongue has been significantly influenced by a better appreciation of the aggressiveness of small deeply infiltrative lesions, the high rate of occult lymph node metastases, and an interest in improving treatment without compromising oral function. Although surgical excision alone has been the mainstay of treatment, combined surgery and adjuvant radiation therapy to include the primary site and regional nodes is commonly used for most advanced cancers (stages III and IV) and is being used increasingly for small stage II cancers that exhibit pathologic indicators of lymph node metastasis or perineural invasion.
For stage I cancers, surgical excision is effective and expeditious, with good preservation of function. For stage II lesions that are infiltrative, hemiglossectomy or partial glossectomy achieves excellent tumor control rates and should be combined with modified dissection of neck nodes (supraomohyoid dissections) to provide accurate information about staging and determination of the need for adjuvant treatment. Hemiglossectomy may result in some functional morbidity in terms of articulation and deglutition. Because of this, radiation therapy may be used in selected cases. Nevertheless, surgery should remain the mainstay of treatment in oral tongue malignancies. For radiation to be as effective as surgery in controlling these cancers, interstitial brachytherapy combined with external radiation is essential. Radiation doses of 80 to 85 Gy are generally given via external megavoltage radiation or in combination with brachytherapy. Such high doses, however, are associated with osteoradionecrosis, fibrosis, and impaired function, and as a result, primary treatment of oral cavity SCCs with radiation therapy is falling out of favor. Interstitial treatment requires precise placement and spacing of implants. Accurate dosimetry is enhanced by using afterloading techniques in which the radioactive source is inserted into previously placed hollow tubes. Tracheostomy at the time of implantation should be considered because of the potential development of tongue edema after implantation. Occult or apparent neck disease is usually treated using external radiation or radiation combined with neck dissection.
Extension of cancer to the floor of the mouth or the mandible may necessitate partial mandibulectomy or segmental mandibular resection. Modern reconstructive techniques with vascularized composite bone and soft-tissue free flaps, titanium metal prostheses, pedicled myocutaneous regional flaps, and free bone grafts have improved the functional and cosmetic results of major mandibular resections. If the neck must be surgically entered to accomplish adequate resection of the primary tumor, a neck dissection should be simultaneously performed. When tumors grossly involve bone, radiation therapy is less effective in these poorly vascularized tissues and requires high doses that are associated with osteoradionecrosis. After local failure of interstitial implants, complication rates for salvage surgical resections are extremely high and are associated with significant morbidity from fistulization, radionecrosis, and failure of primary reconstructive efforts. In many cases, control fistulas and delayed reconstruction with well-vascularized flaps are advantageous. Although the surgical salvage of radiation failures is often successful in early lesions, success drops to less than 50% in advanced lesions.
For more advanced primary lesions (stages III and IV), surgery and external radiation are generally used. Radiation has been administered as either planned preoperative or postoperative therapy, although currently we advocate postoperative treatment in most instances. Although no prospective controlled trials have proved the superiority of combined therapy over surgery alone, many studies indicate improved locoregional control rates. These improvements have generally been offset, in part, by an increased frequency of distant metastases and second primaries. Surgical management generally consists of partial glossectomy and neck dissection, with the mandible being spared unless directly involved. In instances with limited periosteal invasion, coronal and other partial mandibular resections can be performed that spare mandibular continuity and maximize function. Where tumors extend to the midline or involve the tongue base, subtotal or total glossectomy may be necessary. Modern reconstructive techniques have improved the functional results of these aggressive resections. Provision for temporary tracheostomy and prolonged enteral nutrition should be made. Total glossectomy or sacrifice of both hypoglossal nerves frequently necessitates permanent feeding gastrostomy or jejunostomy. Current experience indicates that total glossectomy can often be accomplished without the need for laryngectomy although prolonged enteral feeding will likely be required.
Tumor resection is more difficult after preoperative radiation therapy unless precise tattooing of intended resection margins is accomplished prior to therapy. Likewise, the rates of surgical complications, fistulization, exposed bone, and radionecrosis may be increased with preoperative radiation, although studies have been conflicting. Because of this, most centers have adopted a policy of postoperative radiation. With postoperative radiation, higher doses can be delivered, the extent of disease is precisely defined, the histologic status of the lymph nodes is known, and high-risk areas of close margins or residual cancer can be treated to a high dose. Both ipsilateral and contralateral necks are irradiated, with the dosage determined by the extent of disease. Postoperative radiation should begin within 3 to 6 weeks of resection. Interstitial implants are not used. Close surgical margins require high doses (70 Gy) because of the difficulty in eradicating even small amounts of tumor in the tongue after glossectomy. Curative radiation alone with surgical salvage has been shown to be inferior to combined therapy in control of locoregional disease and in the complication rate, even though survival rates are similar with these approaches. Even with combined therapy, estimated 2-year disease-free and overall survival rates for advanced disease are only 51% and 53%, respectively. The 5-year survival rates range from 50% to 70% for stages I and II to 15% to 30% for stages III and IV (
The management of the neck is of particular interest in patients with tongue cancer because of the high rate of node metastases. For T2 or larger lesions, rates of occult metastases exceed 40%, and some form of neck treatment is generally indicated. When the primary tumor can be adequately excised via a transoral technique, unilateral or bilateral neck dissections should be performed based on the location of the primary disease. Radiotherapy should be used postoperatively if there is perineural spread, extracapsular spread outside a lymph node, or more than one lymph node metastasis.
Revision date: June 21, 2011
Last revised: by Tatiana Kuznetsova, D.M.D.