Positron emission tomography (PET) is a nuclear medicine imaging technique that highlights metabolic activity in the body. PET scanning detects gamma rays emitted by a tracer that is delivered into the body via a biologically active molecule, typically FDG, a form of glucose.
FDG PET is one of the imaging tests sometimes used to help diagnose and monitor mesothelioma cancer on the pleural membrane around the lungs. Now, nuclear medicine specialists in Milan say FDG PET may be even more valuable than clinicians realize for predicting outcomes – especially in mesothelioma patients who are responsive to chemotherapy.
The study involved 131 mesothelioma patients, most of whom were men, with a median age of 66. Study subjects were treated for mesothelioma at Humanitas Research Hospital in Milan between May 2004 and July 2013. Patients received two FDG PET scans – one at baseline before any treatment and another after two cycles of pemetrexed-based chemotherapy.
PET confirmed that 84 percent of mesothelioma patients in the study achieved disease control with chemotherapy. Overall survival for all patients in the study was 14.3 months. The researchers found a clear correlation between baseline PET scan results and overall mesothelioma survival. They also found that patients exhibiting certain metabolic characteristics on PET scans were also the ones who achieved either stable disease or partial response (some amount of tumor shrinkage) after two cycles of chemotherapy.
“Metabolic response…can be used to predict outcome in malignant pleural mesothelioma patients not undergoing talc pleurodesis who achieve stable disease and/or partial response at the interim chemotherapy evaluation,” writes author Egesta Lopci with the nuclear medicine department at Humanitas.
The ability to predict patient outcomes and track response to therapies is critical in the treatment of mesothelioma and many other cancers. Mesothelioma grows and spreads quickly, leaving little room for error in choosing the most effective treatment. The study suggests that FDG PET can provide a clearer picture of treatment responses and probable outcomes.
Lopci, E et al, “Quantitative analyses at baseline and interim PET evaluation for response assessment and outcome definition in patients with malignant pleural mesothelioma”, November 18, 2014, European Journal of Nuclear Medicine and Molecular Imaging, Epub ahead of print