Stereotactic Body Radiation Therapy for Lung Cancer
Neil McGinn, MD
Patients diagnosed with early stage lung cancer are often treated by surgically removing part or all of the affected lung.
But a cutting edge and less invasive treatment available in Maine, is giving patients a much better chance at survival.
The treatment is called Stereotactic Body Radiation Therapy known as SBRT.
Conventional treatment requires as many as 35 doses of radiation up to a 8 week period.
Doctors say the survival rate following this regime is about 60 percent, the outcome for patients that undergo SBRT is more than 90 percent.
Dr. Neil McGinn (Guest): Stereotactic body radiation therapy, which is also known as SBRT or stereotactic ablative radiation therapy, SABR, utilizes advanced technology that has developed over the past few years to localize and to target relatively small tumors in the lungs. Patients presenting with stage I non-small cell lung cancer can receive this treatment instead of surgery, or particularly if they’re not a candidate for surgical resection. The technology has advanced for both imaging the tumor as the patient breathes and targeting the tumor with radiation therapy as the patient breathes. It’s a package of technology that allows for a very high dose of radiation to be delivered precisely to a target that is identified as an early-stage lung cancer.
Melanie: Dr. McGinn, who might be a candidate for this SBRT and who might not be?
Dr. McGinn: Initially, this was technology that was developed beginning about 10 years ago, and it was initially designed for patients who have poor pulmonary function and are not felt to be a candidate for resection. They’re not a candidate for having lobectomy, which is a standard surgical management for early stage non-small cell lung cancer. Again, the therapy was developed for patients who were not a candidate for surgery for pulmonary reasons or for other medical conditions that prevent them from having surgical resection. It was developed and has been successfully applied to some of the sickest patients with early stage non-small cell lung cancer but is now moving into an arena where it’s being considered to be potentially equivalent to surgery, although that’s obviously still controversial.
Melanie: Wow! It sounds amazing. Tell us a little bit about the procedure itself, this type of radiation. What’s involved and what’s involved for the patient? How do they feel during this?
Dr. McGinn: Once the patient has been identified as being a candidate for stereotactic body radiation therapy for lung cancer and has agreed to proceed, we begin with a radiation planning CAT scan. This is very similar to the CAT scan that a patient may have had for the initial evaluation of the cancer, but during this scan, the CAT scan is actually taking images while the patient is breathing and actually creates a four-dimensional representation of the tumor with the fourth dimension being time. We can actually watch to see where the tumor moves as the patient is breathing so that when we develop a radiation treatment plan, we can target anywhere that the tumor might be while the patient is breathing. We start with what’s referred to as a 4D CAT scan. About a week later, the patient comes back to receive treatment. Treatment itself is done in three or four sessions. Each session lasts about an hour, and those are oftentimes scheduled over a course of two weeks. When the patient comes back to receive treatments, they are placed in an immobilization device that was initially created at the time of the planning CT. There on the treatment unit, the machine doesn’t touch them. They don’t feel anything, but they are immobilized in a reproducible immobilization device. The treatment machines now have the capacity to obtain a CAT scan while the patient is on the treatment machine in the position. That CAT scan that’s obtained on the first day of treatment is then used to confirm the location of the center of the target. Additional imaging is taken to confirm that there is reproducibility within just a few millimeters, and then the treatment is delivered. The treatment is delivered as the machine rotates around the patient, usually in four separate arcs or segments. The beam is on continuously while the machine is moving and targeting the central tumor or the central axis of that rotation. This treatment is delivered usually twice a week until they have received their three or four treatments. Patients have no immediate side effects, so they don’t know that they have received anything. Sometimes their shoulders and arms are a little bit sore from being immobilized with their arms up over their head, but there’s no immediate toxicity, and patients really feel quite well. Six weeks after completion of treatment, there is a risk of a radiation pneumonia developing. So this is not infectious pneumonia, but it’s really just inflammation from the radiation that tends to be relatively mild and self-limited occasionally. Steroids are required to diminish the extent of inflammation, but by and large, patients tolerate treatment remarkably well with little, if any, long-term side effects.
Melanie: That is amazing. People don’t realize, Dr. McGinn, that you’re breathing. So that tumor that you’re discussing is moving just as you say so. You’re looking for accurate and precise localization of that tumor while you’re targeting it with radiation. It’s absolutely fascinating. Tell us about the outcomes. What are you seeing as a result of this?
Dr. McGinn: Well, the national studies that have been conducted and reported beginning about three or four years ago have suggested that the ability to control the tumor within the region treated is probably in the range of 90 to 93 percent. Obviously, these patients are at risk for developing recurrence in the lymph nodes, in the chest, and rarely, they can develop recurrence of cancer that has spread elsewhere. But in terms of our ability to control tumor in the region treated, the national studies suggest that it’s within the range of 90 to 93 percent. That’s been our experience as well. We started our stereotactic body radiation therapy program for lung cancer in June of 2011 and through the first year or year and a half, we treated about 40 patients and recently reviewed the outcome of those patients, which trends nicely together with the national data, both in terms of side effect profile and tumor control probability. We currently probably treat about 15 or 20 patients a year, but the program has been running very nicely for the last three and a half, almost four years now.
Melanie: Dr. McGinn, in just the last few minutes, please give your best advice for patients newly diagnosed with lung cancer and what might they discover when they start researching stereotactic body radiation therapy for lung cancer.
Dr. McGinn: This is a great question because as you probably know, low-dose screening CT has recently been recommended and is now approved by CMS for screening patients that are high risk for developing lung cancer. We anticipate that there will be a rise in the incidents of newly diagnosed early-stage lung cancer as a result of the screening. I would encourage patients to make sure that the screening CT is being done through a facility that’s accredited and has a robust screening program in place, and if there is a suspicion of lung cancer, to be seen and evaluated in a multidisciplinary thoracic oncology program such as the program that we have here at Maine Medical Center, which includes a tumor board and a subsequent multidisciplinary clinic that is staffed by thoracic surgeon, medical oncology, radiation oncology with input from diagnostic radiologists and pathologists as well. The most important thing is to be seen in a center that evaluates the patients prospectively in a multidisciplinary fashion and can provide the expertise based on volume to treat patients safely and effectively.
Melanie: Thank you. That is really great information and a fascinating subject. You are listening to MMC Radio. For more information, you can go to mainemedicalcenter.org. That’s mmc.org. This is Melanie Cole. Thanks so much for listening.