Oral cancer medical therapy
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1];Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2]
Overview
The predominant therapy for oral cancer is surgical resection, radiation therapy or a combination of both. Adjunctive chemotherapy/radiation/chemoradiation may be required.
Medical Therapy
Depending on the site and extent of the primary tumor and the status of the lymph nodes, some general considerations for the treatment of lip and oral cavity cancer include the following:
- Surgery alone.
- Radiation therapy alone.
- A combination of the above.
Surgery
For lesions of the oral cavity, surgery must adequately encompass all of the gross as well as the presumed microscopic extent of the disease. If regional nodes are positive, cervical node dissection is usually done in continuity. With modern approaches, the surgeon can successfully ablate large posterior oral cavity tumors and with reconstructive methods can achieve satisfactory functional results. Prosthodontic rehabilitation is important, particularly in early-stage cancers, to assure the best quality of life.
Radiation
Radiation therapy for lip and oral cavity cancers can be administered by external-beam radiation therapy (EBRT) or interstitial implantation alone, but for many sites the use of both modalities produces better control and functional results. Small superficial cancers can be very successfully treated by local implantation using any one of several radioactive sources, by intraoral cone radiation therapy, or by electrons. Larger lesions are frequently managed using EBRT to include the primary site and regional lymph nodes, even if they are not clinically involved. Supplementation with interstitial radiation sources may be necessary to achieve adequate doses to large primary tumors and/or bulky nodal metastases. A review of published clinical results of radical radiation therapy for head and neck cancer suggests a significant loss of local control when the administration of radiation therapy was prolonged; therefore, lengthening of standard treatment schedules should be avoided whenever possible.
Early cancers (stage I and stage II) of the lip, floor of the mouth, and retromolar trigone are highly curable by surgery or radiation therapy. The choice of treatment is dictated by the anticipated functional and cosmetic results. Availability of the particular expertise required of the surgeon or radiation oncologist for the individual patient is also a factor in treatment choice.
Advanced cancers (stage III and stage IV) of the lip, floor of the mouth, and retromolar trigone represent a wide spectrum of challenges for the surgeon and radiation oncologists. Most patients with stage III or stage IV tumors are candidates for treatment by a combination of surgery and radiation therapy. Patients with small T3 lesions and no regional lymph nodes, and no distant metastases or patients who have no lymph nodes larger than 2 cm in diameter, for whom treatment by radiation therapy alone or surgery alone might be appropriate, are the exceptions. Because local recurrence and/or distant metastases are common in this group of patients, they should be considered for clinical trials that are evaluating the following:
The potential role of radiation modifiers to improve local control or decrease morbidity. The role of combinations of chemotherapy with surgery and/or radiation therapy both to improve local control and to decrease the frequency of distant metastases. Early cancers of the buccal mucosa are equally curable by radiation therapy or by adequate excision. Patient factors and local expertise influence the choice of treatment. Larger cancers require composite resection with reconstruction of the defect by pedicle flaps.
Early lesions (T1 and T2) of the anterior tongue may be managed by surgery or by radiation therapy alone. Both modalities produce 70% to 85% cure rates in early lesions. Moderate excisions of tongue, even hemiglossectomy, can often result in little speech disability provided the wound closure is such that the tongue is not bound down. If, however, the resection is more extensive, problems may include aspiration of liquids and solids and difficulty in swallowing in addition to speech difficulties. Occasionally, patients with tumor of the tongue require almost total glossectomy. Large lesions generally require combined surgical and radiation treatment. The control rates for larger lesions are about 30% to 40%. According to clinical and radiological evidence of involvement, cancers of the lower gingiva that are exophytic and amenable to adequate local excision may be excised to include portions of bone. More advanced lesions require segmental bone resection, hemimandibulectomy, or maxillectomy, depending on the extent of the lesion and its location.
Early lesions of the upper gingiva or hard palate without bone involvement can be treated with equal effectiveness by surgery or by radiation therapy alone. Advanced infiltrative and ulcerating lesions should be treated by a combination of radiation therapy and surgery. Most primary cancers of the hard palate are of minor salivary gland origin. Primary squamous cell carcinoma of the hard palate is uncommon, and these tumors generally represent invasion of squamous cell carcinoma arising on the upper gingiva, which is much more common. Management of squamous cell carcinoma of the upper gingiva and hard palate are usually considered together. Surgical treatment of cancer of the hard palate usually requires excision of underlying bone producing an opening into the antrum. This defect can be filled and covered with a dental prosthesis, which is a maneuver that restores satisfactory swallowing and speech.
Patients who smoke while on radiation therapy appear to have lower response rates and shorter survival durations than those who do not;[8] therefore, patients should be counseled to stop smoking before beginning radiation therapy. Dental status evaluation should be performed prior to therapy to prevent late sequelae.