Prognostic Significance of Adipose Tissue Distribution and Metabolic Activity in PET/CT in Patients with Metastatic Colorectal Cancer

PURPOSE

In this study, we aimed to evaluate the prognostic significance of adipose tissue distribution and metabolic activity in PET/CT to predict survival in patients with metastatic colorectal cancer (mCRC).

METHODS

The volume, density (HU), and FDG uptake (standardized uptake value (SUV)) of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) and maximum FDG uptake of the tumor tissue were measured. Subcutaneous adipose tissue of volume-to-density ratio (SAT ratio) was calculated.

RESULTS

The median OS for the patients with SAT ratio value <  -1.1 and ≥  -1.1 were 38.5 (95% CI 31.54-45.58) and 24.5 (95% CI 14.13-34.93) months, respectively (p = 0.05). During follow-up, 69 patients experienced disease progression. The median progression-free survival (PFS) was 11.03 months (95% CI: 9.11-12.95). Median PFS for patients with tumor SUV max value < 11.5 and ≥ 11.5 were 9.2 (95% CI 7.25-11.27) and 12.6 (95% CI 10.02-15.27) months, respectively (p = 0.14). Forty-eight patients received bevacizumab therapy. VAT SUV mean (HR: 0.09; 95% CI 0.01-0.52, p = 0.008) was significantly associated with PFS in patients receiving bevacizumab. SAT ratio was the significant parameter for the OS (HR: 0.58; 95% CI 0.33-1.01, p = 0.05) and PFS (HR: 1.99; 95% CI 1.02-3.91, p = 0.043).

CONCLUSIONS

SAT ratio was an independent prognostic factor for survival in patients with mCRC. Higher SAT volume is correlated with longer survival in mCRC patients.

Treatment with capecitabine + bevacizumab following induction treatment with FOLFIRI + bevacizumab in metastatic colorectal carcinoma

Bevacizumab is a humanized monoclonal antibody that inhibits vascular endothelial growth factor, and it has been found to increase both progression-free survival and overall survival when it is combined with chemotherapeutic agents in the first-line and subsequent treatment of metastatic colorectal carcinoma. The objective of this study was to show the efficacy of maintenance treatment with capecitabine plus bevacizumab in patients with metastatic colorectal cancer who responded to treatment with FOLFIRI plus bevacizumab. The study included patients with metastatic colorectal cancer who received FOLFIRI plus bevacizumab as a first-line treatment. Patients who had objective response with FOLFIRI plus bevacizumab treatment after an average period of 6 months received a maintenance treatment with capecitabine plus bevacizumab (capecitabine 2 x 1000 mg/m(2), 1 - 14 days, every 21 days, bevacizumab 7.5 mg/m(2), every 21 days) until disease progression or toxicity. The time to progression on bevacizumab treatment was evaluated. A total of 29 patients (15 male, 14 female) were included. The mean age was 62 years. The mean number of cycles for maintenance treatment with capecitabine plus bevacizumab was 12. The median PFS was 16 ± 3 months, and OS was 42 ± 11 months. PFS and OS were remarkably higher in patients with a complete or near complete response to induction treatment. Fourteen patients (48%) experienced hand-foot syndrome associated with capecitabine plus bevacizumab treatment, without any severe toxicity. Inselected patients with metastatic colorectal carcinoma who had a remarkable objective response to FOLFIRI plus bevacizumab treatment, a maintenance treatment with capecitabine plus bevacizumab following FOLFIRI plus bevacizumab until disease progression may be a suitable, effective and tolerable regimen, which requires further studies.