Abstract

The utility of serum receptor-binding cancer antigen expressed on SiSo cells in gastrointestinal tract cancers

BACKGROUND: Receptor-binding cancer antigen expressed on SiSo cells (RCAS1) is a novel tumour marker that has been described in various kinds of cancer. The majority of observations include immunohistochemical studies; however, there are not enough data about the utility of this antigen as a serum tumour marker and its tumour specificity.
AIM: To measure the serum levels of RCAS1 in patients with ­gastrointestinal (GI) tract cancers and compare them with other GI tract tumour markers.
PATIENTS AND METHODS: Sera collected from patients with GI cancers (14 esophagus, 32 gastric and 36 colon) and from healthy ­volunteers (30 individuals) were analyzed for RCAS1 and ­compared with ­carcinoembryonic antigen (CEA) and ­cancer ­antigen 19-9. The relationship between serum RCAS1, tumour stage and tumour grade was also evaluated.
RESULTS: Mean serum RCAS1 level was higher in patients with GI tract cancers compared with the control group (P=0.001). Among GI tract cancers, RCAS1 had lowest and highest ­sensitivity for esophagus and colon cancer diagnosis, respectively. Serum RCAS1 had a higher sensitivity for malignancy, except in the colon, and lower specificity in all groups compared with CEA. In comparison with cancer antigen 19-9, serum RCAS1 was more sensitive but less specific for all GI ­cancer groups. Mean serum RCAS1 levels were not statistically significant among histopathological tumour types (P>0.05). Although serum RCAS1 levels were significantly higher in cases with lymph node involvement compared with lymph node-­negative cases (P=0.009), there was no difference between cases with and without serosal involvement, vascular invasion and distant metastasis; no ­correlation was found between tumour size and RCAS1 levels.
CONCLUSIONS: RCAS1 may be used and combined with CEA as a tumour marker in GI tract cancers.