Time to Progression of Pancreatic Cancer: Evaluation with Multi-Detector Computed Tomography

Abstract

Purpose The aim of this study is to evaluate the natural history of untreated pancreatic cancer, with a particular emphasis on the growth rate of primary tumor and development of metastatic disease. Methods One hundred patients with histologically proven pancreatic ductal adenocarcinoma examined with at least two CT scans with no intervening treatment were included. Tumor diameters and volumes were measured in CT scans and tumor growth rates and volume doubling times (VDTs) were calculated. The relationship between initial tumor size, growth rate, and distant metastasis development were investigated. Results Included tumors were 1.0-6.2 cm (mean, 2.9 +/- 1.3 cm) in diameter and 5.5-1225.9 cm(3) (mean, 120.6 +/- 158.9 cm3) in volume at the initial CT. Tumor growth rates were -0.4 to 19.9 cm/year (mean, 4.2 +/- 3.8 cm/year) in diameter, and 11.1-13,321.5 cm(3)/year (mean, 727.8 +/- 1609.5 cm(3)/year) in volume corresponding to VDT of 20.0-976.8 days (mean, 132.3 +/- 132.1 days). The growth rate was significantly associated with the initial diameter and volume (p < 0.001). The development of distant metastasis was significantly associated with initial diameter (p < 0.05), volume (p = 0.015), and volume growth rate (p = 0.002). Conclusions The growth rate and VDTs of untreated pancreatic cancers varied widely, from less than a month to more than 4 years, positively associated with tumor size. The small tumors tend to grow slowly and have low risk for developing metastasis.