The relationship between microscopic tumor size and CT tumor size in pancreatic ductal adenocarcinoma

Abstract

Objectives: To investigate the exact relationship between CT tumor size and the microscopic tumor size in PDAC.

Materials and methods: We enrolled 310 patients with pathologically confirmed PDAC without preoperative adjuvant therapies who underwent CT examination from June 2016 and December 2018. Smooth curve fitting and a segmented regression model were used to analyze the threshold effect between CT tumor size and the microscopic tumor size.

Results: The tumor size was 2.93±1.15 cm under the microscope and 3.00±1.23 cm in CT. The mean bias was 0.067 cm between CT and microscopic assessments. The accuracy of CT T stages was 61.02% (36/59), 79.41% (162/204) and 57.45% (27/47) in T1, T2 and T3, respectively. A non-linear relationship was detected between CT tumor size and the microscopic tumor size, with a turning point of 4.3 cm. On the left of the inflection point, the effect size, 95% confidence interval, and p value were 0.51, 0.40 to 0.63, and <0.0001, respectively. However, we observed no relationship between CT size and microscopic tumor size on the right of the inflection point (0.22, 0 to 0.44, 0.053).

Conclusions: The relationship between CT and the microscopic tumor size is non-linear. When the CT tumor size was <4.3 cm, every 1-cm increase in CT tumor size was associated with a 0.56 cm increase in microscopic tumor size. When the CT tumor size was >4.3 cm, every 1-cm increase in CT tumor size was associated with a 0.91 cm increase in microscopic tumor size.

Keywords: Carcinoma; Neoplasm staging; Pancreatic ductal; Tomography; X-ray computed.