______________________________________________ Oral Cancer and Complications of Cancer Therapies
TREATMENT FOR ORAL CANCER
SURGERY When the diagnosis of oral squamous cell carcinoma is confirmed, plans for surgery and radiotherapy are initiated. Surgery includes the removal of the lesion and its extension into the neighboring hard and soft tissue. Surgical extension into the neck (neck dissection) is usually required to evaluate the extent of the tumor and its spread into local and regional lymph nodes. Areas where surgical deficits are created should be stabilized prior to surgical closure. Muscle from sites such as the pectoralis major muscle may be grafted to repair the surgical wound. Vascular grafts may also be needed to provide adequate circulation for the new muscle grafts. Larger lesions can intertwine around nerves of varying sizes. The removal of these lesions may cause permanent loss of sensation and loss of motor function for many structures in the oral cavity. The loss of hard and soft tissue is commensurate with the size of the lesion. Many patients require the use of maxillofacial prostheses to restore form, function, cosmetics, and self-esteem after these extensive surgical procedures. If a large portion of the tongue is removed, speaking, swallowing, eating, and drinking become arduous functions. RADIOTHERAPY Surgery may not eliminate all squamous cell carcinoma cells. Radiotherapy is utilized to eliminate the cancer cells that may have persisted beyond surgical measures. A common modality used postsurgically, radiotherapy may be rarely used presurgi- cally to decrease the size of larger lesions [34]. The current unit of absorbed radiation is the gray (Gy) or the centigray (cGy). Tumor size, location, and metastasis will determine the required cumulative dosage of radiation. Radiation in adequate doses is cytotoxic to malignant cells because it causes free radical damage to the cellular com- ponents that are required for cell division and replication. Unfortunately, healthy tissues in the area of the radiation beam will undergo the same cellular damage. So, the goal is to destroy the malignant cells with as little damage to healthy cells as possible. The amount of radiation required to destroy all affected cells is too large to be administered in only one dose. Modified fractionation is used to make doses smaller and more tolerable. Most patients receive the same dose of radiation five days a week, over a five-to seven-week period [35; 36]. Because salivary glands are particularly radiosensitive, relatively small doses or irradiation may result in damage [37]. Most radiotherapy is given in fractionated doses of 150–200 cGy per day [35]. Once a cumulative dose of 4,500 cGy has been absorbed, long-term deleterious side effects are encountered. Because most radio-
Kaposi sarcoma in the mouth of a patient with AIDS. Source: National Cancer Institute
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CLASSIFICATION AND STAGING OF ORAL MALIGNANCIES
Before surgery and radiation therapy can begin, classifying and staging of the lesion must be completed. The internationally recognized system is the TNM classification ( Table 3 ), which is based on assessment of primary tumor size (T), metastasis into regional lymph nodes (N), and the presence of distant metastasis (M) [27]. Primary tumor size ranges from TX, at which the tumor can- not be assessed, to a T4 level. The latter assessment indicates that the primary tumor size exceeds 4 cm and has extensive infiltration of the muscle, bone, cartilage, sinus, and/or skin. Lymph node metastasis features more complicated divisions and subdivisions. When the lymph nodes cannot be assessed, an NX designation is given, while N0 indicates a lack of lymph node involvement. The first designation of nodal involvement is N1, which indicates involvement of only one lymph node less than 3 cm in greatest dimension. Progressive nodal involve- ment in terms of number of lymph nodes, their distance from the primary tumor, and the nodal involvement of the same and/or opposite side, continues in this spectrum to a N3 level. Metastatic disease has only three levels of assessment. When distant metastasis cannot be assessed, an MX designation is assigned. No distant metastasis is an M0, while M1 indicates distant metastasis [30]. A chest radiograph is the current method by which metastasis is measured. With this system, lower numbers are equated with a better prognosis. Staging is a system by which the individual components of the classification results are compiled together in stages ( Table 4 ). Due to the asymptomatic nature of the lesions, diagnosis is often delayed [31; 32; 33].
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