Increased glucose metabolism in distant metastasis predicts worse overall survival in patients with metastatic colorectal cancer

Introduction: We assessed prognostic implications of baseline F-18 FDG PET/CT in patients with metastatic colorectal cancer.

Methods: Patients who diagnosed with distant metastasis from colorectal cancer at staging in 2006, and underwent baseline F-18 FDG PET/CT were enrolled. Patients who had a history of other malignancy were excluded. SUV of the mediastinal blood pool (mean), primary tumor (max), and distant metastasis (max) were measured. Primary endpoint was overall survival (OS).

Results: A total of 34 patients (male, 16; female, 18) were enrolled. Among the 34 patients, 2 (5.9%), 28 (82.4%), and 4 (11.8%) had stage IVA, IVB, and IVC colorectal cancer, respectively. Patients were followed up for 61.0 (median; range, 4.0-184.5) months. During follow-up period, 28 (82.4%) patients died. Multivariate analysis revealed that male patients (HR, 3.49; 95% CI, 1.45-8.40; p=0.005), and patients with higher distant metastasis to mediastinum SUV ratio (HR, 1.14; 95% CI, 1.05-1.24; p=0.002) showed significantly poorer OS. Primary tumor to mediastinum SUV ratio did not predicted OS.

Conclusions: We showed that distant metastasis to mediastinum SUV ratio on baseline F-18 FDG PET/CT was associated with poorer OS in patients with metastatic colorectal cancer. These findings may aid in deciding optimal treatment of patients with late-stage colorectal cancer. Further study in a larger number of patients is warranted.