Radiation Therapy: An Overview
Radiation therapy is used mainly as treatment for many different types of cancer. Radiation therapy is used to slow or stop the growth of cancer cells. Radiation uses high-energy X-rays to damage the cancer cells and prevent them from multiplying. In many cases, it can destroy a cancer tumor. Radiation may be used alone or in combination with surgery or chemotherapy. Additionally, radiation may be used to treat other medical conditions, such as epilepsy, Parkinson’s Disease, and arteriovenous malformations. State-of-the-art technology has advanced radiation methods to help make them more effective and tolerable than they were in the past.
How Radiation Therapy Works
Radiation uses high-powered X-rays to destroy cells that grow fast. Cancer cells are fast-growing cells. Radiated cancer cells are not able to repair themselves or replicate. In the process, radiation also kills some healthy cells. Healthy cells are usually able to repair themselves, but damaged healthy cells can cause side effects.
Types of Radiation Therapy
Radiation may be delivered externally or internally. External beam radiation is the most common type of treatment. It uses a machine to aim high-energy beams specifically at a tumor. Internal beam radiation uses radioactive seeds that are placed in or near a tumor inside of the body. The seeds may be left in temporarily or permanently.
In the past, external sources of radiation therapy involved aiming high-beam energy rays at a treatment area. Conventional radiation was associated with side effects and the loss of healthy tissue. Today, sophisticated technology has refined the way that radiation treatment is delivered. Modern radiation methods target the cancer more effectively, spare more healthy tissue, and are associated with fewer side effects and improved cure rates. Some types of radiation therapy include Three and Four Dimensional Conformal Radiation Therapy (3D CRT & 4D CRT).
Three dimensional conformal radiation therapy (3D CRT) maps a tumor with imaging scans before treatment. Magnetic resonance imaging (MRI) scans, computed tomography (CT) scans, and positron emission tomography (PET) scans are used to produce images of a tumor and its surrounding tissue. The images from the scans are combined with a computer called a multi-leaf collimator (MLC). The MLC produces a 3D image of the cancer and formulates a treatment plan specifically for the 3D image. This allows direct multiple beams of radiation to be targeted precisely at the tumor and spare as much healthy tissue as possible.
Four dimensional conformal radiation therapy (4D CRT) measures the motion of tumors during natural small movements that occur during treatment, such as breathing. Four-dimensional CRT is especially useful when treating lung cancer. The motion measurements are included in the treatment formula configurations. This ensures that the tumor is targeted during motions and as much healthy tissue as possible is spared.
Intensity Modulated Radiation Therapy (IMRT)
Intensity modulated radiation therapy (IMRT) is a refined type of 3D CRT. IMRT allows the radiologist to sculpt the edges of a tumor, sparing healthy tissue. With IMRT, the radiation dose can be changed during a treatment session. In the past, radiation was delivered in one dose, from the beginning to the end of a treatment session. IMRT allows the radiation dose to alter and conform more specifically to the shape of the tumor while minimizing the dose received by healthy tissues.
Image Guided Radiation Therapy (IGRT)
Image-Guided Radiation Therapy (IGRT) is a type of external beam radiation therapy for cancer that adjusts for the size and shape of a cancer tumor during treatment. Cancer tumors may move, change size, and change shape throughout the course of treatment. IGRT uses advanced imaging technology to visualize the tumor before each treatment. Based on the daily images, the radiation is configured before each treatment. In turn, the radiation is more precise, effective, and results in fewer side effects.
Stereotactic Radiosurgery (SRS) and Stereotactic Radiotherapy (SRT)
Stereotactic Radiosurgery (SRS) and Stereotactic Radiotherapy (SRT) are both methods of delivering radiation therapy to cancer tumors. SRS or SRT may be used instead of or along with surgery. SRS involves a single radiation treatment. SRT uses a series of treatments over time.
With SRS and SRT, sophisticated software controls the radiation treatment beams to match the exact shape of a tumor or lesion. The beams may be moved to penetrate the cancer from different angles. This precision delivery method quickly allows the cancer to receive the full dose of radiation, while the surrounding healthy tissue only receives a small percentage of radiation.
SRS and SRT are used to treat tumors in delicate tissue areas, such as the brain and spinal cord. It may be used to treat non-cancerous conditions in the brain, such as arteriovenous malformations, neuralgia, Parkinson’s Disease, pituitary adenomas, and intractable seizures. SRS and SRT may also be used to treat lung, liver, prostate, and spine cancers.
MammoSite® 5-day Targeted Radiation Therapy
MammoSite® 5-day Targeted Radiation Therapy is an advanced high-dose partial breast irradiation method for breast cancer treatment. MammoSite following lumpectomy is a breast conservation therapy. For some women, it is an alternative to mastectomy, removal of the entire breast. MammoSite targets the area where cancer recurrence is most likely to occur. Because it is targeted, minimal radiation is delivered to other healthy tissues. It is especially appropriate for early stage breast cancers. With MammoSite, the duration of treatment is shortened from several weeks to just 5 days -- without compromising the outcome.
Brachytherapy- Intracavity and Interstitial
Brachytherapy involves inserting a radioactive source, referred to as a “seed” into or near the cancer. Intracavity brachytherapy involves placing radioactive seeds inside a natural body cavity. Interstitial brachytherapy involves implanting radioactive seeds into or near a cancer tumor. The seeds may be left in place permanently or temporarily.
Brachytherapy is used to destroy cancer cells using an internal source of radiation. Radiation from internally placed radioactive seeds disrupts the growth of cancer cells. Brachytherapy spares as many healthy cells as possible because it directs radiation to only a specific area. Brachytherapy is used as a treatment for many types of cancer, including sarcomas, prostate, breast, lung, gynecological, head and neck, and colorectal cancers.
Radiolabeled Monoclonal Antibody Treatment
Radiolabeled monoclonal antibody treatment is used to treat some types of non-Hodgkin’s lymphoma. Lymphoma is cancer of the lymph/immune system. Bexxar® and Zevalin® are types of intravenous (IV) medication that target and deliver radiation to the cells that grow out of control and form tumors. These medications contain a monoclonal antibody and a radioisotope. The monoclonal antibodies are designed to recognize and attach to a particular part of a cell. Radioisotopes give off radiation. When delivered intravenously, the medication attaches and delivers radiation to the cancer cells, as well as nearby healthy cells.
Your radiation oncologist will discuss your radiation treatment options with you. Radiation therapy may or may not be the only type of treatment that you receive. Radiation may be used to shrink a tumor before surgery. It may also be used after surgery to help prevent cancer cells from returning. Your doctor will prescribe the amount and method of radiation based on the type and location of your cancer. Radiation therapy is usually administered five days a week for two to eight weeks.
Preparation called simulation may be necessary before receiving some types of radiation therapy. During the simulation, your treatment area will be measured and marked on your body. This ensures that the radiation is delivered to the same area with each treatment. Markings may be made on your skin with bright temporary paint or small tattoos. Special blocks or shields may be fabricated to keep the radiation from contacting healthy tissue and shape the radiation beam for treatment. Headrests, molds, casts, and other devices may be created to keep your body in position during treatment.
Radiation therapy is a short procedure. Each treatment usually takes from 15 to 30 minutes. Radiation therapy is painless. It requires that you lay as motionless as possible while you receive treatment. You will receive regular examinations while you are receiving radiation.
The most common side effects of radiation therapy are fatigue and skin irritation. It is important to eat well, participate in your regular activities, and get plenty of rest. Skin reactions may appear a few weeks after your first radiation treatment. You should not use over-the-counter lotions or products on your skin. Your doctor can prescribe a special skin ointment to help relieve your symptoms.
You should not lose the hair on your head from radiation therapy, unless your head is the area receiving treatment. Hair loss may occur in any area that is being treated. The hair loss is usually only temporary.
Dry mouth or mouth sores may occur if you are receiving radiation therapy to your head and neck. Drink plenty of fluids and suck on hard candy or chew sugarless gum to help keep your mouth moist. Your doctor can prescribe a saliva substitute. It may be helpful to avoid irritants such as tobacco, hot food, spicy food, and over-the-counter-mouthwash. You should remove and brush your dentures after each meal.
You may experience diarrhea, nausea, or vomiting if your abdomen area is receiving radiation treatment. Your doctor can prescribe a medication to reduce side effects before each treatment. It may be helpful to eat frequent small meals and drink plenty of fluids. You should avoid alcohol and drinks that contain caffeine.
Radiation therapy can make it difficult to swallow. Your doctor can prescribe medication to relieve pain or make your throat moist to allow for easier swallowing. You should be extra careful when drinking thin liquids because they are more difficult to control when swallowing. Ask your doctor about a thickening agent to help make swallowing liquids safer and easier.
If you receive radiation therapy to the pelvic region, you may experience painful urination as a side effect. It can be helpful to drink plenty of liquids. You should avoid irritants including alcohol, caffeine, citrus juice, and carbonated beverages, such as soda pop.
It is very important to follow your take-home care instructions. It is equally important to tell your doctor or healthcare team if you experience side effects or difficulties. They can help you with problems and suggest ways to reduce side effects.
The experience of cancer and cancer treatments can be a very emotional experience for you and your loved ones. It is important to embrace positive sources of support. Some people find comfort in their families, friends, co-workers, counselors, and faith. Cancer support groups are a helpful resource where you can receive support, information, and understanding from people with similar experiences. Ask your doctor for support groups near you.