Radiation therapy uses a directed radiation beam to damage cancer cells, which may not have been removed during surgery. Radiation therapy can be given as a primary treatment or it can be given in addition to other primary therapies such as surgery. When given after surgery, it is called adjuvant therapy.
Radiation therapy can be delivered in two different ways: externally from a machine called a linear accelerator, or internally through surgically implanted pellets or seeds that give off radiation.
To ensure that your position is always the same, the radiation therapist will often mark the corners of the treatment fields with a small tattoo that the radiation technician uses to line up the treatment fields the exact same way each time. Most cancer centres use tattoo markings instead of ink markings because the ink can wash off. Tattoos are created with a very small needle and a small drop of ink and look like a dark freckle. These steps are taken to minimise damage to the healthy cells surrounding the tumor as much as possible.
Radiation therapy can significantly decrease the risk of cancer returning after surgery. Possible side effects include redness, peeling and soreness of the skin like a sunburn. These are short term side effects and can start a few weeks into treatment and should go away within a few weeks after treatment ends.
Fatigue is also common with radiation therapy and may last for several weeks after treatment.
Longer term side effects may include firmness or shrinkage of the breast. Red discoloration or tanning of the area that was treated may also occur. These changes may be permanent. There is also an increased risk of lymphedema if radiation was given to the lymph nodes under the arm pit area.
Rare side effects may include the potential for rib fracture when the rib cage was weakened near the treatment area. Heart problems may also develop years after radiation therapy is given to the left side of the chest. The chances of this occurring are very low as new techniques are able to limit this risk. Lung inflammation which can result in shortness of breath, a dry cough and low-grade fever. These symptoms can often be managed by anti-inflammatory drugs and will most likely go away with time.
Stereotactic radiation therapy
An alternate form of radiation therapy is called stereotactic radiation therapy. This form of radiation therapy is typically used in the treatment of brain metastases for metastatic breast cancer. It uses an external 3-dimensional beam to target a specific area, most often to the brain. Delivery of stereotactic radiation therapy can be done predominantly through Gamma Knife or CyberKnife systems. This treatment is not available at all cancer centres.
Gamma Knife radiosurgery delivers approximately 200 beams of radiation targeted directly on a tumour. While it uses a strong, single dose of radiation at one time, each individual beam has minimal effect on surrounding brain tissue often lowering side effects. Gamma Knife radiosurgery is non-invasive and does not require an incision; treatment is typically completed after only one session.
The CyberKnife Robotic Radiosurgery System delivers radiation to tumours anywhere in the body, including the brain, lungs, spine and liver. CyberKnife technology uses x-rays to track the tumour with precision while the robotic system moves around the body to deliver radiation at different angles. CyberKnife uses larger doses and the duration of each session is longer than typical radiation treatments. This allows for treatment to be completed after one to five sessions. Similar to Gamma Knife radiosurgery, CyberKnife does not require surgery and because of the extreme accuracy of the system, surrounding tissue is hardly impacted.
These forms of radiation therapy have several advantages. Fewer sessions are needed—as few as one to five. This therapy can be used repeatedly because it is so targeted. And there are fewer side effects because there are fewer doses. Stereotactic radiation therapy is a highly specialized form of treatment. Talk with your treatment team to see if it is available at your cancer centre and if it is right for you.
For more information on stereotactic radiation therapy, visit www.cancer.ca.
Localized therapies, such as surgery and radiation therapy, play an important role in the treatment of breast cancer. It’s important that you understand the risks and benefits of these valuable treatments. If you’re uncertain, be sure to ask your healthcare team for information.