Minsig Choi, MD, Director of Outpatient Medical Oncology and Gastrointestinal Medical Oncology at Stony Brook University Cancer Center, co-authored an article in the March 2015 issue of Clinical Colorectal Cancer regarding the use of PET scans to monitor treatment of patients in advanced stages of colorectal clinical cancer.
“Positron emission tomography (PET) imaging is a modern functional imaging tool that uses fluorodeoxyglucose (FDG)-PET to visualize the higher distribution of glucose uptake that happens in cancer cells,” Dr. Choi said. “PET scans are currently used for staging prior to surgical resection of metastatic colorectal cancer (mCRC), localizing the origin of disease recurrence in patients with colorectal cancer and in the assessment of residual tumor after treatment.
“However, the utility of FDG-PET in prediction and evaluation of response to treating mCRC is not clearly understood,” he said. “In this study, we reviewed 44 patients with mCRC who had FDG-PET before their treatment and measured their standard uptake value (SUV) on follow-up imaging at the Karmanos Cancer Institute. We observed that mCRC patients with metabolic complete response have long-term clinical benefits.
“A complete absence of FDG uptake on follow-up PET scans was associated with markedly longer OS and was suggestive of longer TTP in patients with mCRC,” Dr. Choi reported. “However, the study could not validate currently available criteria (PERCIST and EORTC) used in treatment monitoring for long-term outcomes in advanced colorectal cancer. Therefore, using FDG-PET as treatment monitoring in standard clinical practice has limited value at this time and treatment should not be changed or interrupted based solely on PET scan results.
“Larger studies are required to validate the clinical role of PET imaging in treatment decisions for patients with mCRC, including the risk stratification of patients in clinical trials.