Radiation therapy uses high-energy waves or particles to destroy or damage tumor cells. Radiation creates small breaks in the DNA of cancer cells, preventing them from growing and dividing and often causing them to die.
Types of radiation therapy include external radiation therapy, internal radiation therapy (brachytherapy), and systemic radiopharmaceutical therapy.
Side effects vary depending on the type of radiation therapy and may include fatigue, skin irritation, and low blood cell counts.
Along with surgery, chemotherapy and radiation therapy have long been a mainstay of cancer treatment. It uses high-energy waves or particles such as X-rays, electrons, protons, or alpha particles, to destroy or damage tumor cells. Radiation creates small breaks within the DNA of cancer cells, preventing the cells from growing and dividing, and often causing them to die.
“Radiation therapy is one of the many tools we have available to us to help treat cancer,” says Heather Jacene, MD, Senior Physician and Clinical Director of Nuclear Medicine/PET-CT in the Department of Imaging at Dana-Farber. “There are several different types of radiation therapy, and the team works together to determine the best option at a given time.”
Because cancer cells divide rapidly, they’re more likely to succumb to DNA damage. However, radiation can damage DNA in normal cells as well, leading to a variety of side effects. These side effects depend largely on the type of radiation therapy received. They generally improve over time and can include fatigue, red or irritated skin in the treatment area, and low white blood cell or platelet counts.
Types of radiation therapy
At Dana-Farber, radiation therapy can be delivered in one of three ways:
External radiation therapy, a form of treatment that uses a machine to deliver high-energy rays into a tumor in a way that directly affects cells for fractions of a second. The beams pass quickly through the body and are absorbed by special shields positioned around the room.
Internal radiation therapy, a form of treatment that delivers radiation to either inside a body cavity or within body tissue, is a localized treatment otherwise known as brachytherapy. In this therapy, radioactive material, sealed in a container, is implanted, either temporarily or permanently, next to or inside a tumor.
High doses of internal radiation therapy are given by placing a powerful source of radioactivity in the body for short periods of time. Lower doses are delivered with implants that remain in the body longer.
Patients with permanent implants give off small doses of radiation that get lower and lower with time. As with patients receiving temporary implants, the body fluids and personal items of patients with permanent implants are not radioactive. Because it is low-level, the radiation usually doesn’t travel much beyond the area being treated, so there’s little chance of exposing others to radiation. Still, to be on the safe side, patients may be advised to limit contact with small children and pregnant women.
Systemic radiation, which involves swallowing or receiving an injection of a substance, such as radioactive iodine or radioactive material bound to a tumor targeting agent, travels through the blood to locate and kill tumor cells. This is otherwise known as radiopharmaceutical therapy or theranostics.
“You might think of the tumor as a lock and the radiopharmaceutical as the key,” Jacene adds.
What are the side effects of radiation?
Long- and short-term side effects and symptoms will vary based on the type of radiation a patient is getting. We mentioned a few of these common side effects earlier, such as fatigue, skin irritation, or low white blood cell and platelet counts. All Dana-Farber medical care teams are dedicated to helping ease any discomfort you may be experiencing.
How a radiation treatment plan is made
The way a radiation treatment plan is designed also varies depending on the type of radiation therapy a patient is receiving. At Dana-Farber, multidisciplinary care teams work together to design these plans.
Care teams design treatment plans for a patient receiving external and internal radiation in a three-part process:
- Consultation with a radiation oncologist to discuss the indications, expected results and possible side effects of treatment, as well as to address any questions or concerns from patients. This is usually done on an outpatient basis, but can occur in the hospital for patients who are already admitted.
- A plan to identify the area to be treated. This involves “mapping” with a CT- or MRI-simulator, which produces scans that help doctors identify the best treatment approach.
- After the simulation is completed, a radiation plan is constructed to suit the needs of a given patient.
The process for radiopharmaceutical therapy is:
- Consultation with a nuclear medicine physician, endocrinologist, or radiation oncologist to discuss the expected results and possible side effects of treatment, as well as to address any questions or concerns from patients. This is usually done on an outpatient basis.
- An imaging test, usually a PET scan or SPECT scan, is performed to determine if the tumor target for radiopharmaceutical is present. If the target is seen on the imaging, the patient can proceed with radiopharmaceutical therapy. If the target is not seen, then the care team may discuss other treatment options with the patient. The imaging test usually includes one visit as an outpatient. Occasionally, the imaging test is performed over several days.
Recovering from radiation treatment
Patients who receive radiation treatments can fully recover.
When patients are treated with radiation, nuclear medicine physicians, radiation oncologists, and the care team pay particular attention to how much radiation is being delivered to the cancer and how normal tissues surrounding the area may be impacted.
“Patients are often concerned when they hear the term ‘radiation’ – our care teams are here to make sure this therapy is delivered in a safe manner so patients can have access to this beneficial therapy,” Jacene stated.
All types of radiation therapies undergo the same studies that other cancer drugs and therapies undergo before patients can receive them.
Your care team can work with you to determine which form of treatment is best for you.