Follow-up PET/CT more than 95% sensitive for non-Hodgkin lymphoma
BALTIMORE, MD—For more aggressive cases of non-Hodgkin lymphoma (NHL), posttreatment surveillance with molecular imaging could mean the early start of a new, life-saving treatment. This was presented at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2015 Annual Meeting.
Treatment for non-Hodgkin lymphoma, a potentially devastating cancer of the blood and immune system, can range from relatively easy to very aggressive. NHL is the fifth most prevalent cancer in the United States, according to lead author Mehdi Taghipour, MD, a research fellow from the department of radiology at the Johns Hopkins Medical Institutions in Baltimore.
NHL will be diagnosed in an estimated 71,850 people and 19,790 people will die of the disease this year, according to 2015 statistics from the American Cancer Society.
A majority of patients with NHL are treated successfully with frontline chemotherapy, but approximately 20% to 50% of patients with aggressive lymphoma are expected to relapse within 3 years. Functional and structural imaging with a combination of positron emission tomography and computed tomography (PET/CT) has the potential to catch a relapse in its earliest stages.
"A permanent cure may still be achieved using salvage chemotherapy, but early diagnosis of a relapse is essential," said Taghipour. "PET/CT imaging is superior to conventional imaging for NHL, but the role of posttreatment PET/CT has been controversial. Our study proves that 39% of follow-up PET/CT scans added clinical value, which represents a significant improvement in NHL patient care."
The study included a collective 560 PET/CT scans from 204 patients. Imaging was performed 6 months or more after completion of primary therapy. Researchers assessed the value of follow-up PET/CT by conducting statistical analysis to determine changes in patient management and evaluated the accuracy of these scans comparing to either histopathology or additional 6-month follow-up.
Results of the study showed that the sensitivity of PET/CT for detecting relapsed NHL was 95.1%. Specificity, or the ability to rule out NHL, was gauged at 90.5%. Positive and negative predictive values, which provide insight into the ability of the scan to accurately determine the presence or absence of a disease, were 84.5% and 97.1%, respectively. Lastly, overall accuracy of follow-up PET/CT with the common imaging agent fluorodeoxyglucose (FDG), which provides a map of cellular metabolic activity, was 92.1%.
Follow-up PET/CT led to changes in patient management in 17% of scan times, and new treatments were initiated after 15.7% of scan times. More than 69% of scans were performed without prior clinical suspicion of recurrence, and 30.7% of scans were ordered because of suspected disease, More than 22% of follow-up scans showed suspected disease when there was no clinical suspicion for disease recurrence, and presence of disease was ruled out in 17.4% of scans while the treating physician suspected recurrence prior to the scan.