A combination computed tomography-positron emission tomography (CT-PET) scan is more accurate than either CT scan or magnetic resonance imaging (MRI) at staging mesothelioma, preventing many patients with late-stage cancer from having to undergo invasive surgery, according to a recent study in Clinical Lung Cancer.
A common mesothelioma treatment for earlier stage disease combines chemotherapy, radiation, and extrapleural pneumonectomy (EPP)—a surgery that removes the entire lung, heart lining (pericardium), and diaphragm. Though it is effective at removing cancer cells, EPP is major surgery. Approximately 5% of patients die from the surgery, and many more develop serious complications such as bleeding, respiratory failure, and blood clots. Because of these risks, it is important to determine which patients are the most appropriate candidates before putting them through an EPP procedure. Anyone whose cancer has spread to stage four is not likely to be cured by surgery.
CT and MRI scans are used to stage mesothelioma patients, but research shows they are not very accurate at determining how far mesothelioma has spread. As a result, 25% of patients undergo invasive surgery for cancer that cannot be removed surgically.
A few studies have suggested that the combination CT-PET scan is a more accurate way to stage mesothelioma than either CT or MRI. To evaluate whether this test is of value to patients who are deciding whether to undergo EPP, researchers at the Mayo Clinic retrospectively reviewed the cases of 35 mesothelioma patients who were staged with CT-PET scans. The patients were divided into two groups: those who underwent EPP, and those who were excluded from surgery based on CT-PET scan results.
When the researchers evaluated the scan results, the CT scans showed that four out of 35 patients were at an advanced stage. Yet the CT-PET scan results demonstrated that 16 out of the 35 patients had an advanced stage of cancer. “The CT-PET scan automatically moved a third of patients into a higher stage of disease,” says study author James R. Jett, MD, Professor of Medicine and Consultant in Pulmonary Medicine and Medical Oncology at the Mayo Clinic. As a result of the CT-PET test results, an additional 11 patients were ruled out for consideration of EPP. “CT-PET saves those people the risk of surgery, the morbidity [complications] of surgery, and the cost,” he says.
Dr. Jett and his colleagues discovered that excluding patients from surgery based on their CT-PET scan results did not impact their survival odds. In the group that had surgery, mortality was 80%, compared to 79% in the group that was excluded from surgery.
Additional, larger studies are needed to confirm the role of CT-PET scans in staging mesothelioma. However, this test has quickly become the standard pre-surgical diagnostic and staging technique at large cancer centers around the country. “In my opinion, I don’t think a patient should undergo surgery without a PET-CT,” Dr. Jett says. “I think it’s going to mean that a lot of folks are saved the operation, because the operation doesn’t have the chance to cure them if they’re found to have a higher stage. It’s also likely to improve the outcome for those who do have surgery, because you’re more sure of their stage of disease.”
Wilcox BE, Subramaniam RM, Peller PJ, Aughenbaugh GL, Nichols FC, Aubry MC, Jett Jr. Utility of integrated computed tomography-positron emission tomography for selection of operable malignant pleural mesothelioma. Clinical Lung Cancer. 2009;10:244-248.