New tumor-associated antigen SC6 in pancreatic cancer.
OBJECTIVE
To examine the concentration of a new antigen SC6 (SC6-Ag) recognized by monoclonal antibody (MAb) in patients with pancreatic cancer and other malignant or benign diseases and to understand whether SC6-Ag has any clinical significance in distinguishing pancreatic cancer from other gastrointestinal diseases.


METHODS
Six hundred and ninety-five serum specimens obtained from 115 patients with pancreatic cancer, 154 patients with digestive cancer and 95 patients with non-digestive cancer were used and classified in this study. Serum specimens obtained from 140 patients with benign digestive disease and 89 patients with non-benign digestive disease served as controls. Ascites was tapped from 16 pancreatic cancer patients, 19 hepatic cancer patients, 16 colonic cancer patients, 10 gastric cancer and 6 severe necrotic pancreatitis patients. The samples were quantitated by solid-phase radioimmunoassay. The cut-off values (CV) of 41, 80, and 118 U/mL were used.


RESULTS
The average intra- and interassay CV detected by immunoradiometric assay of SC6-Ag was 5.4% and 8.7%, respectively. The sensitivity and specificity were 73.0% and 90.9% respectively. The levels in most malignant and benign cases were within the normal upper limit. Among the 16 pancreatic cancer cases, the concentration of SC6-Ag in ascites was over the normal range in 93.8% patients. There was no significant difference in the concentration of SC6-Ag. Decreased expression of SC6-Ag in sera was significantly related to tumor differentiation. The concentration of SC6-Ag was higher in patients before surgery than after surgery. The specificity of SC6-Ag and CA19-9 was significantly higher than that of ultrasound and computer tomography (CT) in pancreatic cancer patients. Higher positive predictive values were indicated in 92.3% SC6-Ag and 88.5% CA19-9, but lower in 73.8% ultrasound and 76.2% CT.


CONCLUSIONS
The combined test of SC6-Ag and CA19-9 may improve the diagnostic rate of primary cancer. The detection of SC6-Ag is valuable in the diagnosis of pancreatic cancer before and after surgery.
Liu
Min-Pei
MP
Department of Experimental Medicine, Northern Hospital, No. 83, Wenhua Road, Shenhe District, Shenyang 110016, Liaoning Province, China. liuminp@yahoo.com.cn
Guo
Xiao-Zhong
XZ
Xu
Jian-Hua
JH
Wang
Di
D
Li
Hong-Yu
HY
Cui
Zhong-Min
ZM
Zhao
Jia-Jun
JJ
Ren
Li-Nan
LN
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood*; D018395:CA-19-9 Antigen / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000097:blood / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed
D015295:Antigens, Tumor-Associated, Carbohydrate; D014408:Biomarkers, Tumor; D018395:CA-19-9 Antigen