New Study Shows Prognostic Value of PET Scans in Stage III Non-Small Cell Lung Cancer
Thursday, June 04, 2015
Non-small cell lung cancer is the more common of the two types of lung cancer. For patients categorized as stage III, the cancer has spread to nearby organs in the chest and/or the lymph nodes located between the lungs. These patients are usually not good candidates for surgery, so doctors typically treat them with a combination of radiation therapy and chemotherapy.
“Some of these people can be cured with well-designed chemotherapy and radiation together. But while there have been some advances in radiation technology, the overall treatment unfortunately hasn’t changed much in more than 10 years,” says Mitchell Machtay, MD, Chairman of the Department of Radiation Oncology at University Hospitals Seidman Cancer Center.
Factors that doctors can use to predict how patient might do have also been hard to come by. These are known as prognostic factors.
“In stage III non-small cell lung cancer, other than the age and general health of the patient, there has never been a truly validated prognostic factor,” Dr. Machtay says.
However, Dr. Machtay has led a research group that has changed this equation. In 2013, he and his colleagues published a study showing that PET scans done shortly after combined chemotherapy and radiation were a good predictor of survival. During a PET scan, a small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Cancer cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
Radiation oncologists typically use PET scans to plan how they will target their therapy. But they hadn’t typically used them as a predictor of a patient’s prognosis.
“We thought that the PET scan you use for radiation planning could also give you valuable information about prognosis, and that proved to be the case,” Dr. Machtay says.
Now, Dr. Machtay and his group have expanded on this work. They recently published a study showing that PET scans done before combined chemotherapy and radiation therapy are also a good predictor of how patients with stage III non-small cell lung cancer will fare. Specifically, the study showed that patients with higher pre-treatment metabolic tumor volume (MTV) had poorer survival. MTV is calculated from the PET scan. It is an estimate of the volume of cells in the tumor that are actively using glucose, which indicates growth and aggressiveness of the cancer.
The study was published in the Journal of the National Cancer Institute and was one of the largest trials to date on this subject. It included academic medical centers like UH Seidman Cancer Center, but also community hospitals and international sites in Canada and South Korea.
For Dr. Machtay, the findings of this study point toward a better way of designing clinical trials involving patients with stage III non-small cell lung cancer.
“Current studies typically divide patients by clinical stage, such as IIIA and IIIB,” he says. “Our findings here suggest that investigators should instead use factors such as MTV.” Giving those patients with high MTV more intensive therapy may lead to better outcomes, he says, but trials must be designed to prove that. Dr. Machtay is currently one of the national leaders of a clinical trial evaluating intensified radiation therapy, based on findings from patients’ mid-treatment PET scans. This study, and several other stage III non-small cell lung cancer clinical trials, are available at UH Seidman Cancer Center.
For more information on the thoracic oncology program at UH Seidman Cancer Center call 1-800-UH4-CARE (2273).