Monitoring Metastatic Melanoma Using FDG PET/CT
Posted: Monday, April 29, 2019
Patients with metastatic melanoma being treated with ipilimumab can be monitored using 18F FDG (fluorodeoxyglucose) positron-emission tomography/computed tomography (PET/CT). Wolfgang A. Weber, MD, of the Technical University in Munich (formerly of Memorial Sloan Kettering Cancer Center in New York), and colleagues published data to help accurately assess tumor response in this patient population in The Journal of Nuclear Medicine.
“FDG PET/CT is routinely used to stage melanoma,” explained Dr. Weber in a Society of Nuclear Medicine & Molecular Imaging press release. “The present study suggests that it also can be used to monitor tumor response to ipilimumab therapy and predict outcome. FDG PET can identify patients with favorable and unfavorable prognoses—leading to therapy escalation (eg, combination immunotherapy) or de-escalation (eg, reduced number of therapy cycles).”
For this study, 60 patients with metastatic melanoma received FDG PET/CT scans before and after treatment with ipilimumab. Tumor response for up to five tumors was assessed through the change in the sum of the standard uptake value normalized to lean body mass (SULpeak; PERCIST5). New inflammatory lesions were assessed using immunotherapy-modified PERCIST with a 5-lesion analysis (imPERCIST5). In PERCIST5, new lesions indicated progressive metabolic disease, whereas imPERCIST5 included new lesions in the quantification of tumor 18F FDG uptake, and progressive disease was defined as an increased sum of SULpeak by more than 20%.
Evaluation of tumor response with PERCIST5 correlated significantly with survival of patients with advanced melanoma. imPERCIST5 improved the prognostic value of the response assessment by 18F FDG PET/CT as well (hazard ratio = 3.853). For responders, the 2-year overall survival was 66% compared with 29% for nonresponders. New sites of focal 18F FDG uptake were seen more often in patients with progressive metabolic disease or partial metabolic response.
Disclosure: The study authors’ disclosure information may be found at jnm.snmjournals.org.