Treatment of oral cancers is ideally a multidisciplinary approach.
Early stage of oral cancer is typically managed with either surgery or radiation therapy alone. Although they have almost equal success in the control of local recurrence, the side effects from radiation persuade more clinicians to recommend a surgical option. Advanced-stage tumors require multi-modality treatment, which includes combining surgery with radiotherapy and possible chemotherapy. For these reasons, a patient diagnosed with oral cancer is usually presented at a multi-disciplinary tumor board conference where head and neck /oral and maxillofacial surgical oncologists , radiation oncologists, medical oncologists, radiologists, pathologists and rehabilitation therapists discuss the best treatment options for each patient individually. Although tumor thickness (depth of invasion) is not mentioned in the TNM staging system, it is an important predictor of neck lymph node metastases.
Surgical Treatment
The goal of surgical treatment is to remove the tumor at the primary site (oral cavity) and to ensure that the lymph nodes that are at risk for harboring tumor metastasis are in fact free of disease. Teeth may also need to be removed as part of the surgical cancer treatment, or to help in the prevention of osteoradionecrosis ( jaw bone death) as a result of previous or subsequent radiation treatment. In addition to the oral surgical portion of the procedure, “neck dissection ” is generally performed. Neck dissection involves the removal of a number of lymph nodes that, based upon the clinical and histological characteristics of the primary tumor, are at known risk of metastasis. A neck dissection is typically performed even in the absence of clinical and radiographic evidence of lymph node enlargement.
Today, less invasive operations are often done to remove tumors and to try to preserve as much normal oral cavity structure and function as possible. Surgery offers the greatest chance for cure for many types of cancer, especially those that have not yet spread to other parts of the body. When the disease is localized, a surgical procedure may be able to remove the cancer entirely . Most people with cancer will have some type of surgery.
Postoperative radiation therapy is generally recommended for patients with large primary tumors, those with certain adverse histopathological features, the presence of “positive margins” (incomplete resection of the oral lesion), and/or the presence of cervical lymph node metastasis. Chemotherapy may also be added in a small number of patients with advanced stage disease who have either positive resection margins or in whom the cervical lymph node metastasis has extended outside of the lymph node itself.
Radiation Therapy
Radiotherapy, also called radiation therapy, is the treatment of cancer with ionizing radiation. Ionizing radiation deposits energy that injures or destroys cells in the area being treated (the target tissue) by damaging the genetic material (DNA) in the individual cells, making it impossible for them to continue to grow. Although radiation damages both cancer cells and normal cells. Normal, healthy cells are able to repair themselves and return to proper functioning.
The total dose of radiation therapy prescribed by the radiation oncologist is broken down into small amounts (fractions) which are given on a daily basis, usually five days in a row with a two day break each week. It has been found that patients better tolerate the smaller daily doses while still receiving the maximum benefit of the treatments.
Exposure of the oral cavity to radiation will produce mucositis, making the interior of the mouth quite sore. This will resolve after the radiation treatments have been completed. Another complication associated with radiation treatment of the oral cavity or throat, is xerostomia due to the damage of the salivary glands during the course of treatment. This results in a permanent loss of salivary function (xerostomia). New techniques such as IMRT (intensity modulated radiotherapy) are being implemented at more cancer centers, which can avoid this collateral damage to the salivary glands. Using a different software program to administer the radiation from multiple angles in smaller doses, this technique also includes a new shuttering device to limit the size of the radiation beams which are emitted, thus missing the glands and sparing them any exposure to the destructive radiation.
Chemotherapy
One of the main technologies used for cancer treatment is chemotherapy. Chemotherapy is the use of chemicals to destroy cancer cells. Chemotherapy works by interfering with the cancer cells ability to grow. It is one of the three main methods utilized to treat cancer. Radiation therapy and surgery are also important; both of which may be used in conjunction with chemotherapy.
What makes chemotherapy very effective, is that it has the ability to treat widespread (metastatic) cancer, that is in more than one location in your body. This ability makes chemotherapy very important in a patient’s fight to overcome cancer, because radiation therapy and surgery are only suitable for treating cancer in localized areas.
When these three treatments are used in conjunction, their complimentary avenues of attacking the disease frequently offer the patient the best chance to beat cancer.
The administration of chemotherapy can be accomplished in several ways. The most common means are oral and intravenous, but chemotherapy may also be administered intramuscularly or through catheters.
When the chemotherapy has been completed, the non-cancerous cells return to their normal functions, or are replaced by new healthy cells, and the symptoms cease.
RECONSTRUCTION AND REHABILITATION
The structures found within the oral cavity are very complex not only in terms of their shape, but also in function. The action of the oral cavity is facilitated by the saliva, which provides many functions including that of a lubricant.
Surgical removal of cancerous tissues can significantly affect the daily function of the oral cavity and cause a significant diminution of the patient’s quality life. With this in mind, reconstruction of the acquired defect is often carried out during the same operation in order to minimize the functional and cosmetic effect on the patient.
The goals of reconstruction are to reestablish near normal function as it relates to speaking and eating in addition to maintaining facial appearance. Small oral defects can often be repaired with tissue from within the mouth by either closing the defects primarily or rearranging the tissue near the defect. Larger defects often warrant the transfer of similar tissues (bone, soft tissue or a combination of the two) from regional or distant sites in order to carry out the reconstruction.
One of the major advances in the treatment of patients with oral cavity cancer in the past 20 years has been the use of vascularized tissue transplantation. In this technique the tissues needed are harvested from their donor site along with the feeding artery and vein in the neck. The reconstructive options are numerous. The most commonly used tissue , however , are the forearm skin ( called radial forearm free flap), the thigh skin ( antero-lateral thigh flap), the chest skin and muscle (pectoralis major flap), bone from the lower leg (fibula free flap), bone from the hip or bone from the shoulder blade ( scapula free flap).
When the upper jaw( maxilla) is removed, the defect can be reconstructed using one of the options already discussed or a specialized denture (obturator ). The major goal of maxillary reconstruction is to provide a separation of the mouth from the sinus and nasal cavities. Dental implant reconstruction can also be performed either immediately or it can be delayed until the patient has healed from the initial surgery and completed any additional therapy.
Surgery, radiation and chemotherapy treatments can affect speech and swallowing function. After the initial surgery, patients often need a speech therapist to assess their speech and swallowing , as well as to instruct them in using their residual muscle and reconstruction to perform those functions.. Occupational therapists may also be involved in the rehabilitation of oral cancer patients.
FOLLOW-UP AND TUMOR SURVEILLANCE
After oral cavity cancer treatment, follow-up care is essential to evaluate for recurrence . Over 80% of cancer recurrences are detected within the first 24 months following initial treatment .The oncologist will likely request the patient to return for clinical examination every three month for the first two years after treatment. Tumor surveillance will also include periodic imaging, such as CT scan, PET scan and MRI tests to help look for recurrent disease at the original oral cancer site, spread to lymph nodes of the neck, or metastases to distant body sites ( lungs/ liver). Patients treated with radiotherapy will also need blood tests to evaluate the thyroid gland. Occasionally the gland is adversely affected by radiation fibrosis and some form of thyroid hormone replacement would then be required. Most patients return for an annual exam once they have reached the five-year oral cancer free interval.
If a cancer recurrence or a new cancer (second primary cancer) occurs, the patient will be re-evaluated and various treatment options, including surgery, radiation therapy and chemotherapy, may be presented. I general, radiation therapy can only be delivered once to the same area within the head and neck.
When found at early stages of development, oral cancers have an 80 to 90 % survival rate. Unfortunately at this time, the majority are found as late stage cancers, and this accounts for the very high death rate of about 43% at five years from diagnosis (for all stages combined at time of diagnosis), and high treatment related morbidity in survivors. Late stage diagnosis is not occurring because most of these cancers are hard to discover, it is because of a lack of public awareness coupled with the lack of a national program for opportunistic screenings which would yield early discovery by medical and dental professionals.
Worldwide the problem is far greater, with new cases annually exceeding 640,000.
This is the fifth year in a row in which there has been an increase in the rate of occurrence of oral cancers, in 2007 there was a major jump of over 11% in that single year.