Transcription
When an individual has been diagnosed with a form of head and neck cancer, radiation therapy is a very common treatment modality that may be recommended. Radiation therapy takes advantage of the finding that for many types of cancers, tumor cells are more effectively killed by radiation exposure than are non-tumor cells. As the tumor cells are killed off in greater numbers by radiation exposure, the tumor both shrinks in size and allows for normal healthy cell repopulation. In addition to this, a beam of radiation can be aimed at the target of interest.
After an initial consultation with a radiation oncologist, the following prepatory steps are taken to ready a patient for radiation treatment. Planning the areas to be treated by radiation is a process of outlining the anatomic extent of the tumor as well as areas of known or high potential for tumor spread. Endoscopy, biopsy, and imaging are typically used for this purpose. A custom mesh of the patient’s face, neck and shoulders is created. This radiation mask is used to keep the head and neck absolutely still in an identical manner each and every time a patient has radiation therapy, while allowing the patient to breathe easily. Once the mask has been created, a CT simulation scan is performed to obtain 3D images used for treatment planning. This scan allows the radiation oncologist to precisely target the tumor and surrounding areas that will require radiation exposure, while sparing normal tissues as much as possible.
Before radiation therapy begins, the patient will need a dental evaluation and possible treatment. Any teeth with bad cavities will require extraction whereas more minor cavities can get a filling. Some situations call for the use of chemotherapy or immunotherapy to be used during the course of radiation therapy, for which the patient would consult with a medical oncologist. Some patients may be advised to have a feeding tube placed before treatment begins.
After all initial planning has been completed, radiation therapy can proceed. During this process, the head and neck is secured to the table with the mask to ensure consistent precise positioning throughout the entire course of radiation treatment. Radiation therapy is accomplished by directing a beam of high energy x-rays that is molded to precisely the cancer’s 3D shape via the multi-leaf collimator. Instead of giving the entire radiation dose in a single day which would cause excessive damage to normal tissues, smaller radiation doses are given each weekday to improve outcomes. Collectively, the total dose still reaches the desired level. Furthermore, the radioactive beam is rotated continuously around the cancer to ensure healthy tissue is not overly exposed, but collectively, keeping the focus of the radiation beams all centered on the cancer itself. The gantry of the radiation machine rotates around the patient slowly. After check-in and positioning, a single treatment takes only a few minutes. Treatment is performed every day except on weekends. Treatment usually takes about 6-7 weeks. If chemotherapy or immunotherapy is given, it is typically administered once every 7 to 21 days for a total of 3-7 doses and works by increasing the radiation’s ability to destroy cancer cells.
Common side effects of radiation therapy to the head and neck include temporary reactions to the skin and throat, fatigue, and altered sense of taste. Longer-term consequences may include persistent dry mouth and throat, jaw problems, teeth weakening, and neck and throat stiffness. The cancer could start shrinking during the course of radiation therapy and may resolve completely shortly thereafter. The recommendation for radiation therapy, with or without chemotherapy or immunotherapy, is based on the expected response of a specific tumor versus expected side effects or potential alternative therapy types.