Radiation Therapy for Lung Cancer
Radiation therapy plays a pivotal role in the treatment of lung cancer of all stages and can result in long-term curative outcomes for patients with early stage disease.
Radiation treatments and care offered for City of Hope's lung cancer patients include:
Stereotactic Ablative Body Radiotherapy (SABR)
SABR, also referred to as Stereotactic Body Radiation therapy (SBRT), is a technologically innovative form of radiation treatment that enables delivery of high doses of radiation to the tumor over a shorter number of treatments. In published studies, this has been shown to confer a primary tumor control rate exceeding 80 percent. At time of its initial development, SABR was restricted to frail and elderly patients who were not medically fit to tolerate surgery.
Currently, SABR is being offered to our patients in two scenarios: (1) to those patients whose medical conditions preclude them from surgery after evaluation by a thoracic surgeon and (2) those patients who refuse surgery. Research studies are currently being done to examine SABR for patients who are also healthy surgical candidates, and these results will be available over the coming years.
At City of Hope, we use a form of radiation delivery known as intensity modulated radiation therapy (IMRT) for SABR treatment. IMRT allows for the radiation beam to be blocked in specific areas during the therapy session, minimizing exposure to normal tissues.
SABR is not considered standard treatment if you have lymph node involvement.
4D CT treatment planning
Because the lung is a constantly moving organ, our team uses four-dimensional computed tomography (4D CT) scans to help guide treatment. This advanced scanning technique helps determine the tumor’s movement within the body, so that radiation can be adjusted to target the cancer and not surrounding normal tissues.
To achieve this goal, you will receive a four-dimensional CT (4D CT) that allows the physician to track your tumor’s motion and draw an area that captures this trajectory. This same CT will be used to calculate the radiation doses for planning. We also will be applying gentle pressure below your sternum bone to encourage you to take shallower breaths during the CT scan and treatment, reducing lung tumor motion. With more limited lung motion from our compression technique and acquiring 4D CT information, we can reduce normal lung tissues' radiation exposure compared to older techniques due to a much high level of certainty that the tumor is now in the field of radiation.
This is a technique where the radiation machine is turned on only during a portion of the tumor’s trajectory, usually the end of exhalation. In patients whose lung tumors move substantially as seen at time of 4D CT, gating can allow for smaller radiation field and less normal tissue exposure. This technique requires patients to breathe consistently over long periods of time, which may not be feasible for some patients.
Using gating can increase a patient’s treatment time by approximately 50%, and therefore your physician will discuss with you the justification for its use, if necessary, along with other risks and benefits.
Radiation Therapy for locally advanced (Stage II-III) disease
If the lung cancer is very large or has involvement of the lymph nodes, radiation therapy can be a curative option when given at the same time as chemotherapy. The length of treatment will be 6-7 weeks. The majority of patients will be treated on the Tomotherapy machine, which delivers radiation using a technique called intensity modulated raidation therapy (IMRT), with automatic image-guided radiation therapy. Generally, IMRT will allow for greater normal lung sparing compared to traditional techniques, and also help minimize exposure to other nearby organs, such as the esophagus and heart.
Day of treatment
SABR patients are treated on our state-of-the-art TrueBeam STX linear accelerator, which was installed in October 2012, or the Tomotherapy machine.
The treatment appointment will be approximately 45 minutes to 1 hour. The majority of this time will be devoted to setup on the treatment table to match the same position at the time of the planning CT scan. Next, we will obtain a low-energy CT scan in the area of the tumor, which will then be fused to the original planning CT scan. We will then make very small adjustments based on this information. This is known as image-guided radiation therapy (IGRT). Finally, the treatment will begin, which will last for approximately 3-4 minutes.
The radiation oncologist will visit with patients at least once during the entire treatment course. Any questions or concerns can be addressed during these visits.
Follow-up care and surveillance
Patients will receive their first CT of the Chest approximately 3 months after treatment is completed to monitor the response to therapy. Repeat scans will take place every 3 months. Typically, it can take 9 months to 1 year to fully determine whether the lung tumor has responded to therapy. This is because significant changes to the lung tissue around the tumor can occur during this time period.