Evaluation of clinicopathological variables and survival
Clinicopathological variables studied included 14 factors: sex, age at surgery, preoperative serum CA19-9, preoperative serum carcinoembryonic antigen(CEA), preoperative serum CA242, tumor location, type of surgery, TNM stage,T stage, N stage, histology grade, lymphovascular invasion, perineural invasion and postoperative adjuvant chemotherapy.
The levels of preoperative serum tumor markers (CA19-9, CEA and CA242) were detected within 1 week before surgery. The normal upper limits of serum tumor markers were adopted as follows: CA19-9 (37.0 U/ml), CEA (5.0 ng/ml) and CA242 (20 U/ml). In this study, all patients with total bilirubin ≥ 250mmol/L were treated with percutaneous transhepatic biliary drainage or endoscopic retrograde biliary drainage. After biliary darinage, the level of preoperative serum CA19-9 was detected again.
The pathological diagnosis was established by two professional pathologists. Tumors were staged according to the 8thedition of AJCC TNM staging of pancreatic cancer. The histology grade were classified into two groups based on the degree of tumor differentiation: low grade, including well or moderately differentiated adenocarcinoma; and high grade, including poorly differentiated or undifferentiated adenocarcinoma. Lymphovascular infiltration (LVI) was referred to as blood vessel and lymphatic invasion. Perineural invasion is an infiltrative process of peripheral nerves by the primary neoplasm within the immediate vicinity. Patients who received more than three cycles of postoperative adjuvant chemotherapy were defined as chemotherapy group.