Elevated Serum Synuclein-Gamma in Patients with Gastrointestinal and Esophageal Carcinomas

We aimed to evaluate whether elevated serum synuclein-gamma levels were of clinical significance as a serological marker in cancer diagnosis and monitoring.Pre-treatment serum synuclein-gamma levels of patients with gastrointestinal and esophageal squamous cell carcinomas, benign disease and healthy controls were analyzed by a specific sandwich ELISA for synuclein-gamma.Statistically significant differences in serum synuclein-gamma levels between patients with colo rectal cancer, gastric adenocarcinomas, esophageal cancer and healthy individuals were observed (p<0.001). When a cut-off value for synuclein-gamma was determined at ≥4 ng/mL by receiver operating characteristic curves, sensitivity and specificity were 16.4% and 97.7% in colorectal cancer, 23.0% and 99.3% in gastric adenocarcinomas, and 19.5% and 98.7% in esophageal cancer, respectively. Compared with carcinoembryonic antigen and carbohydrate antigen 19-9, synuclein-gamma was more sensitive in early detection of colorectal cancer (17.3% vs. 9.6% and 7.5%), gastric adenocarcinomas (20.6% vs. 0% and 3.2%) and esophageal cancer (22.2% vs. 3.4% and 0%), respectively. A combined analysis of the above markers yielded incremental positive rates compared with anyone alone.These results indicated that serum synuclein-gamma provided a promising diagnostic biomarker for early detection and was a complementary biomarker of carcinoembryonic antigen and/or CA19-9 in gastrointestinal and esophageal cancer.