Radiation therapy, or radiation oncology, involves using targeted, penetrating rays of energy (radiation) to destroy cancer cells. In the treatment of breast cancer, radiation therapy can be used before surgery to shrink a tumor or after surgery to kill any remaining cancer cells. Like surgery, radiation therapy is a local therapy in that it affects cancer only in the treated area.
The team of radiation oncologists, oncology nurse specialists, dosimetrists, physicists and therapists at the Swedish Cancer Institute (SCI) and its Center for Advanced Targeted Radiation Therapy work together to provide the very best care and are influential in the development and delivery of the latest radiation technologies available.
External Beam Radiation Therapy
External beam radiation therapy is produced by a machine called a linear accelerator. Short, targeted bursts of x-rays are fired from the machine at the cancer. As with any cancer treatment, a detailed treatment plan must be developed for external beam radiation therapy. The treatment plan helps determine the exact area where the treatment needs to be focused. This area is called the "treatment field."
The first step in determining the treatment field is an information-gathering process called a "simulation." Even with a patient lying still, a tumor will move during external beam radiation therapy because of breathing and other normal bodily movements.
Previously, to compensate for the movement and to ensure the entire tumor was treated, radiation oncologists had to target the tumor as well as some surrounding healthy tissue. Today, advanced technologies help radiation oncologists plan and apply external beam radiation therapies that target the tumor while sparing as much of the surrounding normal tissue as possible.
Technologies used at the SCI to develop a treatment plan and then ultimately treat breast cancer using external beam radiation therapy include:
Active Breathing Coordinator (ABC) - protect your heart: Caring for patients with left-sided breast cancer and protecting the heart is now as easy as ABC at Swedish. The Swedish Cancer Institute at Swedish/First Hill and Swedish/Issaquah offer patients the option to use an Active Breathing Coordinator (ABC) during radiation therapy. ABC is a noninvasive device that assists a patient with holding their breath for 10 seconds. When you hold your breath, your heart automatically shifts away from your left breast.
Learn more about ABC
4D CT Imaging: The SCI was an early adopter of 4D imaging that allows physicians to visualize the motion of breast tumors over a patient's breathing cycle, resulting in improved design of each patient's treatment plan.
Image-Guided Radiation Therapy (IGRT): Swedish was the first in the Northwest and among the first in the world to offer this innovative procedure. Radiation beams come out of the linear accelerator in a square-shaped manner. To spare as much of the surrounding normal tissue as possible, the radiation oncologist designs special blocks to shape the radiation beam. With IGRT, the linear accelerator is joined to a CT scanner. This allows for near real-time imaging of the tumor prior to treatment, improving the precision of the radiation delivery while reducing the exposure of radiation to normal tissue.
Intensity-Modulated Radiation Therapy (IMRT): For years, Swedish physicians have been at the forefront of researching IMRT applications. With IMRT, the radiation beams are broken up into numerous pencil-sized beams. These smaller beams, or beamlets, can be conformed to the shape of the tumor in three dimensions. As a result, high doses of radiation can be directed at the cancer while reducing damage to nearby tissue.
PET/CT Scanner: Radiation oncologists at Swedish were among the first in the Northwest to use a 16-slice PET/CT scanner for radiation-treatment planning. The scanner combines Computerized Tomography (CT) and Positive Emission Tomography (PET), two standard medical imaging tools. The PET/CT scanner allows the tumor to be defined more precisely by better identifying the junction between cancer and inflamed normal tissue. This, in turn, allows the radiation oncologist to more effectively plan the dose of radiation to the cancer while sparing more of the healthy tissue.
Volumetric Modulated Arc Therapy (VMAT): The SCI was one of the first cancer centers in the United States to introduce this novel radiation therapy delivery technique. During VMAT treatment, the radiation machine rotates around the patient in a series of arcs delivering focused beams of radiation to the cancer. The shape and intensity of the radiation beams changes as the machine rotates. These features mean that, in effect, the beam of radiation can come from an infinite number of angles, thereby reducing the dose of radiation to normal tissue while increasing the dose to the cancer. The arc-based delivery also allows the radiation oncologist to treat tumors that are adjacent to critical structures in the body, such as a tumor that may be wrapped around an organ.
Brachytherapy for Breast Cancer
Following a lumpectomy, a short course of radiation is often an acceptable treatment plan for many women. Traditionally, whole-breast irradiation uses a radiation source outside of the body, such as external beam radiation, to treat the cancer site. This usually involves daily treatments of six days per week over a six- to seven-week period.
Using partial-breast irradiation methods, such as brachytherapy, maximizes the dose delivered to the area most at risk of breast-cancer recurrence while minimizing radiation exposure to surrounding healthy tissue. Partial-breast irradiation treatments can be completed in about five days, rather than six or seven weeks, allowing patients to return more quickly to their day-to-day lives.
Brachytherapy — also known as internal radiation therapy or interstitial radiation — is done by implanting a radioactive source inside or next to the cancer site. At Swedish, High-Dose Rate (HDR) brachytherapy methods are used in the treatment of breast cancer.
As the name implies, HDR involves the temporary placement of a high-dose, concentrated radiation source directly in or around the cancer site. The direct placement helps spare surrounding healthy tissue while the high dose can mean a shorter treatment time compared to more traditional radiation therapies, typically about five days rather than six or seven weeks. Methods of HDR brachtherapy used at Swedish for breast cancer include MammoSite® Brachytherapy, Contura™ Multi-Lumen Balloon Brachytherapy and Axxent™ Electronic Brachytherapy.
Because these methods treat only the portion of the breast affected by cancer and offer shorter treatment periods, they are also referred to as Accelerated Partial-Breast Irradiation (APBI) techniques.
Learn more about the APBI methods used at Swedish
Stereotactic Radiosurgery (CyberKnife)
In addition to the breast-brachytherapy methods available, the Swedish Radiosurgey Center at Swedish/Cherry Hill is currently evaluating the technical feasibility and acute toxicity of partial-breast irradiation with the CyberKnife radiotherapy device, as well as quality of life issues as they relate to treatment-related side effects, cosmetic result and patient convenience. Radiosurgery is defined as the very precise delivery of a short course of radiation. Radiosurgery in the context of this protocol will be given to the lumpectomy site within seven weeks of the surgery over a period of five to 10 days using the CyberKnife device. Eligible patients will receive their radiosurgery before chemotherapy is given.
Learn more about CyberKnife
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