Introduction
Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal
malignancies. According to the World Health Organization, the estimated
number of new cases of pancreatic cancer ranked 12th among all malignant
tumors in 2020[1]. The 5-year survival rate was
approximately 11.5%[2]. Multiple disciplinary
therapy based on the tumor stage and biological characteristics of
primary lesion is highlighted in improving the survival of patients with
PDAC. Therefore, it is vital to classify PDAC more accurately.
The American Joint Committee on Cancer (AJCC) tumor-node-metastasis
(TNM) staging system is the most commonly used classification for the
prognostic evaluation and treatment decision of
PDAC[3]. The TNM classification has undergone
continuous improvement to reflect the current understanding of the
extent of disease[4]. Several studies have
clarified the accuracy of the TNM staging of Pancreatic Cancer (8th ed.,
2017) [5,6,7], in contrast, several other studies
demonstrated no survival differences between stages of TNM
classification and proposed modified TNM or newly staging system[8,9].
Tumor biology shows significant impact on the prognosis of patients with
malignancy and has been incorporated into the staging system to improve
the accuracy of prognostic prediction[10,11].
Since both tumor burden and malignant degree could reflect the
characteristics of tumor biology[12,13], we
supposed that combination of the factors which represent tumor burden
and malignant degree would provide a full understanding of tumor biology
on prognosis of cancer, and incorporating factors associated with tumor
biology into staging system could improve the accuracy of the TNM
staging system in predicting prognosis. Carbohydrate antigen 19-9
(CA19-9) is associated with the tumor burden [14]and histology grade is associated with the degree of
malignancy[15,16]. Therefore, the combination of
preoperative serum CA19-9 and histology grade could reflect the tumor
biology of PDAC. In the present study, we retrospectively analysed the
data of 612 patients with PDAC who underwent curative resections. The
aim of this study was to explore the combined effect of preoperative
serum CA19-9 and histology grade on the prognosis of patients with PDAC.