(18)F-FDG PET has proven invaluable in the staging of patients with metastatic colorectal cancer. The aim of the current study was to determine whether this biologic scan would correlate with other cellular characteristics and the clinical behavior of tumors.
Methods: Ninety patients with resectable colorectal cancer metastatic to the liver underwent (18)F-FDG PET before hepatectomy. At surgery, tumors were harvested and prepared for assessment by histology and immunohistochemistry. Expression of Ki67 (a marker for cell proliferation), GLUT1 and GLUT3 (markers for glucose transportation), p53 and p27 (markers for cell cycle control), and BCL-2 (a marker for apoptosis) was assessed by a pathologist who was unaware of the PET results and the clinical outcome. Patients were followed to determine outcome. Survival analysis was performed comparing patient outcome in groups segregated according to standardized uptake values (SUVs) greater or less than 5, 7, or 10.
Results: Maximum SUV correlated with GLUT1 (P=0.03), Ki67 (P=0.026), and p53 (P=0.024) but did not correlate with p27, BCL-2, or GLUT3. Survival was significantly longer for patients with a low SUV than for patients with a high SUV, with P values of 0.014, 0.025, and 0.0095 for SUV cutoffs of 5, 7, and 10, respectively.
Conclusion: (18)F-FDG PET is a biologic scan that predicts prognosis in patients with metastatic colorectal cancer. It is uncertain if this ability is due to cellular glucose metabolism or to a correlation with other cellular characteristics of aggressive tumors.