ORAL COMPLICATIONS DURING CANCER TREATMENT: LECTURE (p. 1)

SURGERY. Some times surgery is the only choice and especially in malignancies of the head and neck regions, the result often is marked disfiguring with consequent loss of function and altered facial features. Other sequelae to surgery of malignancies of the oral cavity are major disabilities in tongue mobility, extensive loss of teeth and bone, areas of anesthesia as a consequence to nerves ablation and alterations in tissue vascularity.

RADIATION THERAPY. Radiotherapy alone is used in the treatment of malignacies which are radiosensitive such as lymphomas or Kaposi's sarcoma among others. Some tumors, such as the epithelial cancers of the upper aerodigestive tract, including the oral cavity, are moderately radiosensitive. In these regions radiotherapy is generally used in cancers which are three or less centimeters in diameter. Ionizing radiation to the head and neck regions is administered by means of external beams of x-ray or gamma rays or external beams of electrons directed to the tumor or by local implantation (brachytherapy) of radioactive needles of cesium, radium, gold, palladium or other metals which also emit x-rays or gamma rays. Most of the radiation treatments for head and neck cancers consist of a total dose of 50 to 80 Grays (Gy) distributed in fractioned doses of 10 Gy per week during five weeks, at a rate of 2.0 Gy every 24 hours during a 5 day period (1 Gy = 100 rads). This modality will induce oral mucosal changes (mucositis - vide-infra), when the radiation dose is increased the mucosal changes are more severe and the possibility of osteoradionecrosis increase.

CHEMOTHERAPY. This modality of cancer treatment is used in combination with surgery or radiotherapy especially in advanced cancers. Carcinomas grade III (poorly differentiated) or IV (undifferentiated, Broder's scale) of the head and neck regions, fall within the group of cancers that are treated with this type of combination therapy. The objectives of chemotherapy are to control the development and growth of distant metastasis, to destroy circulating neoplastic cells, to aid in the local control of the cancer by reducing tumor size and to improve the cure and survival rates. There are several drugs which are used in cancer chemotherapy but the most frequent are: 1) Bleomycin which is a mixture of glycopeptides, 2) Cisplatin which is a heavy metal compound, 3) 5- Fluorouracil which is a pyrimidine metabolite and is the most frequently used drug to treat head and neck cancers and 4) Methrotrexate which is an antimetabolite. All these drugs induce toxic side reactions which include mucositis, skin erythema, myelosuppression with leukopenia and alteration in lung, kidney and neural functions. All these drugs are used as a single agent or in combination as well as concurrent with radiation therapy.