Serum tumor markers carcinoma antigen (CA) 72−4 versus carcinoembryonic antigen (CEA) in patients with early stage (IA−IB) gastric cancer

Background: In the European Union, gastric cancer (GC) is the seventh most common cancer. Its prevalence is relatively low compared to the eastern Countries, accounting for approximately 14 cases per 100,000 per year. However, it should still be considered an aggressive disease because the estimated 5-year survival ranges between 71% and 57% in stage IA and IB patients, respectively. A number of serum tumor markers (TM) are commonly measured in patients with GC, both for diagnostic and prognostic purposes, including carcinoembryonic antigen (CEA), and carcinoma antigen (CA) 125, CA 19-9, CA-242 and CA 72-4. The aim of this study was to evaluate the usefulness of CA 72-4 versus CEA in patients with early stage GC. Patients and methods: We retrospectively reviewed the medical charts of 36 selected patients (median age 61 years, range 35-79 years) who underwent curative surgical resection for IA and IB AJCC/UICC stage GC. There were 26 (72.2%) men and 10 (27.8) women. Exclusion criteria were a history of other malignancy, preoperative neoadjuvant chemotherapy, alcohol abuse or smoking, or the use of drugs potentially interfering with the serum levels of TMs, as well as those with liver or kidney failure. Controls were 37 sex- and age matched patients in whom gastroscopy excluded the presence of GC or peptic ulcer. Written informed consent was obtained from all the participants. TMs assay was obtained with commercially available kits, according to manufacturer’s instructions. CEA was measured by automated homogeneous chemiluminescent (CLIA) immunoassay (luminescent oxygen channeling immunoassay-LOCI, that uses a dyoxetan derivative as luminescence substrate), whilst CA 72-4 was measured by a solid phase enzyme-linked immunosorbent assay (ELISA) based on the sandwich principle, both applied on the Maglumi 2000 Plus automated platform (Shenzen New Industries Biomedical Engineering - SNIBE, Shenzen, China). The cut-off levels were 5 ng/ml and 4 U/mL for CEA and CA 72-4, respectively. The chi-square (χ2) test was used to compare results. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) at 95% confidence interval (CI) were calculated. The accuracy, false positive rate (α), false negative rate (β), likelihood ratio positive, likelihood ratio negative and odds ratio (OR) were also obtained. The software Statistica (StatSoft, Tulsa, OK, USA, version 2012) was used for statistical analysis. Results: The results are reported in the Table. The sensitivity of CA 72-4 was significantly higher than that of CEA (30.6% vs. 11.1%, χ2=4.31, p=0.04) at the same specificity (94.6%), but the accuracy did not differ (63.0% vs. 53.4%, χ2=1.38, p=0.24). Using the two TMs together, both the sensitivity (47.2%, χ2=2.10, p=0.14) and the accuracy (72.6%, χ2=1.54, p=0.21) did not improve significantly. Conclusion: CA 72-2 is more sensitive than CEA in detecting patients with GC, at the same specificity and similar PPV. However, simultaneous measurement of both TMs is not useful.