TOP

Radiation

What is radiation therapy? How does it work? What are the side effects of treatment? Learn about how radiation affects your body when you undergo chemotherapy.

What is Radiation Therapy?

Radiation therapy is the treatment of cancer with ionizing radiation. In the most basic sense, ionizing radiation damages the DNA of cells as they try to divide and replicate. Cells that are dividing and replicating faster are more susceptible to DNA damage from radiation therapy. Therefore, because cancer cells are rapidly dividing, they are more likely to be destroyed by radiation than normal cells in the body.

However, some normal cells in the body divide and replicate more frequently than other normal cells in the body; for example, cells lining the mouth and throat are constantly regenerating, as are skin cells. This is why when a patient is treated with radiation for a cancer inside the mouth or throat, one of the major side effects is mucositis, or inflammation of the mouth and throat lining.

Pros & Cons of Radiation Therapy

One advantage of radiation over surgery is that it can be administered on an outpatient basis, which means a patient will not have to be admitted to the hospital. It also avoids the risks of general anesthesia during surgery, which is particularly important for patients with many medical problems or even just one severe medical problem. Additionally, radiation therapy allows for the possibility of organ preservation; for example, patients can be treated for cancer of the larynx (voice box) without the removal of the larynx.

One disadvantage of radiation is that patients need to come into a treatment facility 5 days per week for 6 to 8 weeks (though this schedule can vary). Additionally, there are a number of side effects, both immediate and long-term, that need to be considered.

Uses of Radiation Therapy

The selection of the best treatment for a patient is a decision that is made after a discussion with a patient’s doctor. The decision will depend on many factors, including the type of cancer, the location of cancer, previous treatments and other medical problems.

Types of Radiation

In general, radiation may be utilized in several different settings. Primary radiation is used as the initial form of treatment for a cancer. Adjuvant radiation, is used following surgical removal of the cancer in order to reduce the risk of recurrence. Reirradiation is used after a prior course of radiation, when cancer has recurred or a new cancer has developed in the previous field of radiation. Radiation for metastatic disease, in the setting of cancer spread to other sites in the body such as the lung, bone or brain that are amenable to further treatment.

Definitive Radiation Therapy (with or without Chemotherapy)

Definitive radiation therapy means that the main treatment of the cancer is radiation. It can be combined with chemotherapy, which is called definitive chemoradiation therapy. The advantage of this approach is that it allows for organ preservation in some cases. If there is evidence of persistent cancer, or if the cancer returns in that very location, the next step for treatment will be surgery to remove the cancer.

Adjuvant Radiation Therapy (with or without Chemotherapy)

This is the use of radiation therapy after surgical removal of all of the obvious cancer. Carefully planned radiation after surgical resection has been shown to decrease the chance of the cancer coming back. This is probably because the radiation kills any microscopic cancer cells that were not obvious during the surgical resection. In some cases, post-operative radiation might be combined with post-operative chemotherapy to further decrease the chance of cancer returning after surgery.

Neoadjuvant Radiation Therapy (with or without Chemotherapy)

This strategy is used mainly in clinical trials or certain cases of advanced disease. In neoadjuvant radiation therapy (with or without chemotherapy), the non-surgical treatment is given, and then followed up with surgery afterwards. This allows pathologists to study the response, and if there is any cancer remaining, a surgeon can remove it.

Palliation of Symptoms

When cancer has spread to distant sites, or when all standard treatment measures have failed and additional surgery is not an option, radiation can be used to palliate symptoms (which means make a person feel better or prevent a major complication that could impact quality of life). An example of this might be cancer that has spread to the bones of the spine; this can be quite painful and radiation can treat the tumor there without making a patient go through surgery.

Laser - Computed tomography

Radiation Therapy Delivery Methods

Therapeutic radiation is commonly used in the treatment of head and neck cancers.

Due to the necessity of administering this treatment from an external source, it is important to understand that normal tissues located in the path of the beam will be affected along with the tumor cells that are targeted. The essence of the treatment planning that takes place is to limit the amount of radiation that the normal tissues receive and to maximize the dose to the cancer cells. Certain structures are very sensitive to radiation such as the carotid artery and the spinal cord and protection of these structures in the treatment planning phase of therapy is essential in order to minimize complications. This is known as the Therapeutic Ratio. 

Radiation therapy is an important form of treatment for most types of head and neck cancer. It may be used individually, in combination with chemotherapy, or as additional therapy (known as adjuvant therapy) following surgical removal of the tumor. There are a number of different ways to administer radiation therapy. The two main techniques for most head and neck cancers are external beam radiation therapy and brachytherapy.

Standard External Beam Radiation Therapy

This is the main form of radiation therapy for head and neck cancer. Either X-rays or gamma rays are used in standard external beam radiation therapy. The current standard of care in delivering external beam radiation for head and neck cancer is to use intensity-modulated radiation therapy (IMRT). In a basic sense, this is a way to adjust the dose delivered in over 100 thin beams of energy in a three-dimensional space. By adjusting each beam individually, a radiation oncologist can design a plan that gives little radiation to normal tissue and maximal radiation to cancerous tissue. The goal of radiation is to optimize the dose to the cancer and the immediate surrounding tissues and to minimize the amount of radiation delivered to normal tissues that are in the vicinity or the direct path of the beam. This decreases, but does not eliminate, side effects of radiation therapy when normal tissue is affected. See our ‘What to Expect’ section below to learn more about the patient experience during this radiation treatment.

Brachytherapy

This is a form of radiation in which the source of radiation, usually a tiny radioactive “seed,” is implanted very close to or actually within the cancerous mass. In contrast to external beam radiation therapy, brachytherapy uses needles (catheters) placed through the skin to the target area. The radioactive implants can be temporary or permanent.

The main advantage of brachytherapy is that it can deliver a greater amount of radiation directly to the targeted tumor, while sparing normal tissue. In addition, brachytherapy affords the opportunity to administer continuous radiation. The disadvantages of brachytherapy are the necessity of a well-defined tumor due to the ineffective delivery of radiation to poorly-defined growths.

Brachytherapy catheters or seeds are placed in the operating room while the patient is asleep. They are positioned such that the area of each implant that emits radiation sits immediately next to the targeted cancerous tissue.

For the placement of brachycatheters, a surgeon might perform a tracheotomy once the patient is under anesthesia; this is just a precaution in case there is any significant swelling or bleeding that might cause difficulty breathing. This is commonly performed when treating cancers in the base of tongue. The tracheotomy tube is typically removed after a few days. Once the patient is asleep, the radiation oncologist will proceed with placing the catheters. The catheters are placed through the skin and positioned in such a way that the area that emits radiation is positioned within the treatment area. Once the required number of catheters are in place, the patient will awaken and be taken to the recovery room. 

The next step is to load the catheters with a radiation source. This is done in a private room to limit exposure of the clinical staff or other patients to radiation. Currently, for the head and neck, the brachytherapy catheters can be left in place for about five to seven days to deliver a substantial dose of radiation, or they can be used as a boost to a very specific area for about two to three days after giving external beam radiation.

Intraoperative Radiation Therapy (IORT)

IORT is a type of external beam radiation therapy that uses a high dose of very targeted therapy. This treatment is directed at a specific area at risk of harboring microscopic cancer cells after all the obvious disease has been surgically removed. In the head and neck, IORT is used in a few select centers, mostly in patients who have extensive cancer that has returned after previous radiation therapy. It is usually administered following the removal of a locally advanced and often recurrent cancer.

After surgical removal of all obvious cancer, the radiation oncologist will enter the operating room and place an applicator in the area where microscopic cancer cells are likely to be. Along with a team of scientists, the radiation oncologist will devise a treatment plan and use a mobile linear accelerator to administer the radiation over a period of about 30 minutes. This must be done in a special shielded room with cameras to monitor the patient asleep on the operating room table. The cameras are critical because all personnel must leave the operating room, including the anesthesiologist, while the radiation is being administered. IORT is generally considered safer than administering an additional dose of external beam radiation therapy because normal tissue around the tumor bed can be pushed out of the way, retracted, and shielded. IORT is also administered to a very focused area where there is concern for residual tumor. There is no standard dosage for IORT, but it typically ranges from 10 to 20 Gy (Gray unit). In certain cases, the combination of IORT and surgery may give the best chance of curing recurrent cancer, while lowering the risks of major complications. This method is not standard care at this time. Studies are ongoing to determine the exact role of IORT for recurrent cancer in the head and neck.

Neutron Beam Radiation Therapy

This type of external beam radiation is only available at a few sites in the United States. Higher energy neutron beams have greater cell killing capability per dose and might be better-suited to overcoming radioresistance. This is particularly important in large tumors with areas of low oxygen and in large slow-growing tumors. For head and neck cancer, the role of neutron beam radiation therapy remains somewhat experimental and can be considered for a select few salivary gland cancers (such as adenoid cystic carcinoma). Neutron beam therapy is considered in patients with tumors that are dangerous to resect, or in cases where surgical removal may leave the patient with considerable side effects.

Proton Beam Radiation Therapy

This type of external beam radiation is also only available at a limited, but growing, number of centers around the world. Proton beam radiation therapy uses protons (rather than the standard X-rays or gamma rays) to kill cancer cells. The advantage of using protons (as opposed to X-rays or gamma rays) is the more precise delivery of radiation. This should result in less damage to normal tissue and thereby decreased side effects. The uses of proton beam radiation in the head and neck are currently under study and rapidly expanding. The proximity of vital structures such as the eye, carotid artery, the brain and the spinal cord  to the targeted field of radiation may serve as indications for this form of radiation.

Robotic Stereotactic Radiosurgery

Though called radio-“surgery,” it is more accurately a delivery of very tight beams of radiation from multiple different directions to focus on a very specific target area. Radiosurgery is known by several names, including Cyberknife®, Gamma Knife® and LINAC. It is mostly used for small intracranial brain tumors, and is not a major form of treatment for head and neck cancers.

Radioactive Iodine (RAI)

This is a form of radiation that is NOT external beam. RAI is used to treat certain stages of well-differentiated thyroid cancer (as well as some cases of benign thyroid disease). It works on the premise that thyroid cells use iodine, so when a patient drinks a radioactive form of iodine, the thyroid cells will take up the iodine and be destroyed. In theory, this should destroy thyroid cells anywhere in the body. For this to be effective for thyroid cancer, any thyroid tissue that can be removed surgically should be removed prior to administering radioactive iodine. RAI is administered as a drink or a capsule, and should not destroy normal tissue because most normal tissues do not take up iodine. Side effects of RAI might include dry mouth, nausea, and fatigue; some patients also complain of a metallic taste in the mouth. In addition, patients will need to take some special precautions after treatment.

What to Expect During Radiation Therapy

In preparation for radiation therapy, a patient will meet with their doctor to discuss their upcoming radiation treatment. During this visit, there are a series of preparation steps that must be done before the actual treatment sessions begin. This initial visit is commonly longer (2 to 3 hours) than subsequent visits because a doctor will prepare the patient physically and mentally for their upcoming treatment sessions, discussing the purpose and logistics of treatment as well as performing the imaging studies that will guide treatment sessions. The latter process is referred to as simulation.

Initial Visit: Simulation Day (2–3 hours)

A patient will meet with radiation therapists, who will describe the radiation mask, how it’s made, and the physical experience the patient will go through during the session. If IV contrast is being used in the patient’s imaging, the patient will come to the appointment after fasting for several hours, and meet with nurses who will prepare them for IV contrast. 

After the IV is prepped, the simulation process takes place. A mask made of perforated plastic is warmed up in an oven or a warm water bath. This process takes about 10–15 minutes, during which time the patient is positioned face up so their neck is in a reproducible position on the custom headrest. Depending on the case, the patient may also have a bite block to separate the jaw or immobilize the tongue. A bite block can be shaped like a popsicle or a similar shape to a dental mold, and is placed in the mouth as comfortably as possible so it can be positioned the same way each day.

The mask is then softened and ready. The patient is positioned such that the spine is straight, the shoulders are even, the chin is up, and the head is in a neutral position and not turned. There is a limited time to create the fitted mask, so the mask is quickly placed onto the patient’s face, around their jaw, and across the neck and shoulders. Therapists gently mold the mask so it forms to the patient’s shape to limit motion during treatment and improve the safety and accuracy of the treatment. Masks can be attached to the table through a number of different attachments, including plastic plugs that hook into the table or clip and foam pads, making the mask quite secure. The importance of the mask and this process is that it allows the position of the patient to be accurately replicated on a daily basis through treatment.

It takes about 5 minutes for the plastic mask to “cure” and become firm. During this time, the radiation therapist will make sure the patient is not moving or deforming the mask outside of its intended shape. After the mask is firm, the patient has some time to become comfortable breathing in the correct position under the mask. Before the mask is taken off, the CT imaging portion of the simulation takes place. The scan is usually done with IV contrast, scanning from the top of the head through the chest. The whole imaging process takes just a few minutes.

Following CT imaging, the therapist and radiation oncologist work together to select a reference point known as the isocenter. Using this reference point, marks are made on the mask and patient’s skin. These marks are very small tattooed dots that allow for accurate positioning during each treatment session. Patients will be counseled on the experience of getting tattooed alignment dots.

After the marks are made, the mask is taken off and the patient is given a schedule for the first treatment day. Arrangements are also made for the full treatment course. At this point, the patient is ready to go home and prepare for their first day of radiation treatment.

Initial Treatment Day

The first treatment session is typically the longest treatment session in the course of a patient’s radiotherapy. This is because the first session involves quality assurance measures and safety checks to be performed before the first course of radiation is administered. For patients who are also receiving chemotherapy, the longest portion of the first day will involve the chemotherapy treatment, and can range from a few hours to an entire workday (6-7 hours). Following that, the first session of radiation can begin.

The session begins with the positioning of the patient by radiation therapists, who follow instructions from the previous simulation session and treatment plan. At this time, the patient also undergoes position verification imaging which can be in the form of cone beam CT or X-ray. This entire preparation process can take 20-25 minutes. The patient is then positioned on the table in the same way as during the previous CT simulation. The table is typically under a big machine in the middle of a large cavernous treatment room kept cold. After the patient is positioned correctly, a linear accelerator rotates around the patient’s head and neck. The accelerator doesn’t touch the patient and stays about a meter away from the patient during imaging and treatment. This takes up the majority of the time the patient spends in the treatment room.

Treatment itself is painless and takes only a few minutes. It is typically delivered while the machine is rotating around the patient at many different angles. The patient usually won’t even be able to tell the difference between imaging and treatment, as neither causes immediate symptoms or pain. This concludes the first treatment session.

After the first treatment, the radiation therapist and patient will become accustomed to each other and the therapy instructions. Treatment time usually decreases to approximately 15–20 minutes in the treatment room during each subsequent visit. Treatment is typically given on weekdays, and lasts 6 weeks (30 sessions) to 7 weeks (35 sessions) depending on the patient and their disease status.

Side Effects of Radiation Therapy

There are a number of side effects of radiation therapy. The likelihood and severity of complications occurring depends on several factors, including the total dose of radiation delivered, duration of treatment, and location of the head and neck region receiving radiation.

Xerostomia (Dry Mouth)

The most common short-term and long-term side effect of radiation therapy for the treatment of head and neck cancer is xerostomia (dry mouth). It occurs when salivary glands are radiated or in the path of the radiation. Besides the limitations this places on patients’ abilities to eat and speak, xerostomia increases the risk of dental cavities and dental disease due to the decreased amount of saliva in the mouth. While the incidence of xerostomia is lower with new treatments such as intensity modulated radiation therapy (IMRT) in which the radiation therapist can more precisely control how much radiation is given to different areas, this complication still remains. Patients learn to manage xerostomia in a number of ways, including frequent drinking of liquids and the use of artificial saliva preparations. Also, certain medications given around the time of radiation might lessen the severity of xerostomia (e.g. pilorcarpine, amifostine).

Osteoradionecrosis (Bone Death)

This is necrosis (or death) of bone that has been exposed to radiation. The bone most commonly affected is the mandible and, less commonly, the maxilla. The bone often becomes exposed through the skin or mucosa and can progress to an actual fracture of the bone. Osteoradionecrosis (ORN) can cause severe pain as well as chronic and persistent infections. In ORN, trauma (such as removal of bad teeth within a jaw bone that has poor blood supply from radiation) can lead to all the symptoms of ORN. If a patient needs dental work after head and neck radiation, they should consider seeing a dentist who is familiar with the treatment of ORN. The main treatment of ORN is really prevention. All head and neck cancer patients who will receive radiation should see a dentist before treatment to make sure the teeth are in the best possible shape; any diseased teeth should be removed approximately three weeks or more before starting radiation treatment. After radiation, patients should take very good care of their mouths, including frequent cleaning and daily fluoride treatments. Once ORN sets in, treatment might include antibiotics, frequent debridement, and sometimes even hyperbaric oxygen dives. In severe cases of ORN, where pain, infection, and the risk of fracture are present, removal of the diseased bone may be required. In these circumstances, the jaw is reconstructed with a microvascular free flap to transfer bone with an independent vascular supply. At some point, a patient might require a segmental resection of all diseased bone and reconstruction using a microvascular free flap.

Trismus (Reduced Ability to Open Jaw)

This inability to separate the jaw can be short-term or long-term depending on the extent of change in the chewing mechanism of the jaw (joint, bone, and muscles), injury, and patient compliance to treatment exercises and best practices.

Odynophagia

This is pain with swallowing. It can be initiated when the mouth and throat lining starts sloughing off and becomes inflamed (mucositis). It can be treated by swishing and swallowing liquids that numb the pain, or in some cases strong pain medication. Rarely, if a patient is not able to eat or drink for an extended period of time, a doctor might suggest placement of a feeding tube until the patient gets through the painful phase.

Mucositis

Mucositis is the inflammation of the digestive tract’s lining, which can cause constant pain that is often worsened when eating.

Dysphagia (Difficulty Swallowing)

This is related to a change in the swallowing mechanism, and can be short-term or long-term depending on how large the change was and how compliant the patient is with rehabilitation exercises.

Skin Changes

Skin changes depend on the extent of a patient’s radiation field, total radiation dose, and genetics. Skin reactions during radiation therapy are very patient-specific, but are usually not permanent. Broadly, patients typically develop darker skin color, mild redness, and swelling by halfway through treatment. This continues through the rest of treatment, and may be accompanied by skin peeling. Patients can also experience acute skin changes such as severe erythematous reactions. Temporary or permanent hair loss in the region that receives radiation is also common.

Taste Changes

Taste changes will be more or less pronounced depending on the extent of the radiation field and how much of the tongue was involved in the radiation field. Changes in taste generally occur by the end of the second week of treatment. This will begin with the dulling of certain flavors and gradually the intensity of all flavors will dull or decrease. Some patients note that most foods begin to taste bitter or unpleasant. For the majority of patients, taste sensation will recover following treatment. This recovery is gradual, and depending on the extent of the radiation field and severity of taste change, can take from 3 months to over 2 years.

Hypothyroidism

The thyroid gland is located low in the central neck and is often in the path of the radiation beam for cancers of the larynx, trachea, hypopharynx, and esophagus. Therefore, damage to the thyroid gland can occur following radiation for head and neck cancers. This will result in hypothyroidism, or an underactive thyroid, which can actually be quite delayed in its presentation. The doctor should routinely check thyroid function with blood tests, especially with new symptoms such as new onset of fatigue or significant weight gain. Hypothyroidism can be effectively treated by taking a thyroid hormone substitute pill (Synthroid, levothyroxine, or others) once a day. Blood tests can be drawn following the start of replacement therapy to determine the effective dose that the patient should be using for long term therapy. In patients who require surgery, their hypothyroidism should be managed prior to undergoing that procedure.

Increased Phlegm Production

Patients may develop thick phlegm related to dry mouth and inflammation of the mouth and throat. Although medications are not generally recommended and the symptoms are typically managed with swish and gargle therapy and frequent hydration. Occasionally, medications such as Mucinex and guaifenesin can help decrease the amount of mucus.

Pharyngoesophageal Stenosis

Pharyngoesophageal (PE) stenosis is an area of narrowing in the pharynx or esophagus. This can be another delayed problem caused by radiation. This narrowing can make it difficult to eat, particularly solid food. If the PE segment becomes completely closed off, the patient won’t be able to eat or drink anything by mouth and will require a feeding tube placed directly into the stomach (gastric tube). Treatment of this complication might include frequent placement of dilating catheters down the throat to stretch open the narrowed segment or surgical removal of the blocked segment with flap reconstruction. The rendezvous procedure often used to treat this complication is performed using an endoscope which is passed through the stomach at the gastrostomy tube site on one side and passed through the mouth on the other side. This allows for the narrowed segment to be dilated on both sides.

Secondary Cancers

Paradoxically, even though radiation is used to treat cancer, years later it can actually result in new cancers appearing. The risk increases with high dosage and greater time since treatment. The secondary cancer can be quite different from the original and could include lymphomas, sarcomas, and leukemias. Secondary cancer is very rare and typically occurs at least ten years following radiation treatment. A radiation oncologist will talk to their patient about this risk, particularly if they are a young patient with head and neck cancer.

Dentistry - Oral hygiene

Important Considerations During Radiation Therapy

Nutritional Management

It is important for patients to maintain weight during radiation therapy. This ensures the radiation mask will continue to fit throughout the course of treatment and ensures treatment remains accurate. It is often helpful for patients to think of eating food and meeting their caloric goals as part of their treatment regime, rather than a chore.

Dental Care & Oral Hygiene

  • Before beginning radiation therapy, the patient should meet with the dental & oral surgery team for a full dental evaluation, just as if the patient were going to the dentist for a regular check-up. The dental team will perform a regular exam, take dental X-rays, and provide recommendations on how to maintain good dental care and manage personal dental issues during radiation therapy. 
  • If the patient has teeth that may need removal or may not be salvageable or the patient may not be able to maintain a certain level of dental hygiene throughout radiation treatment, teeth may be removed preemptively, so long as it doesn’t interfere with the radiation therapy timeline. This prevents post-treatment complications like osteoradionecrosis (ORN), discussed later in this section.
  • At some medical centers, dentists may also create mouth guards (or dental/fluoride trays) for patients to wear during treatment. This may help protect the gums and teeth during treatment. They may also be used at home with prescription strength fluoride treatment from the dentist.
  • Patients should practice vigorous oral hygiene including flossing and brushing as tolerated, as well as adequate hydration.

Skin Care

Patients should use skin creams that help maintain moisture and provide a protective barrier to treated skin. For skin peeling, creams with antimicrobial properties like silver sulfadiazine can help. For the strongest skin reactions, wound care treatment is administered, including wet to dry dressings, non adherent dressings, and antimicrobial dressings.

Humidification & Hydration

Patients should keep a humidifier at the bedside to maintain moisture throughout the airway. As patients experience worsening dry mouth, hydration is advised for oral comfort and the maintenance of adequate dental hygiene.

Subscribe for more…
Get notified of updates, news and upcoming events sent to your inbox!
Subscribe for more…
Get notified of updates, news and upcoming events sent to your inbox!