Immunoreactive carcinoembryonic antigen [CEA] levels in feces from colorectal cancer patients

Fecal CEA Has an Advantage in the Diagnosis of Colorectal Cancer at Early Stage

Purpose

Serum carcinoembryonic antigen (SCEA) level is often measured in patients with CRC but suffers from poor sensitivity and specificity as a diagnostic biomarker. CEA is more abundant in stool than in serum, but it has not been widely studied. This study aimed to elucidate the efficacy of fecal CEA (FCEA) as a potential non-invasive biomarker for early diagnosis of CRC.

Materials and Methods

We retrospectively analyzed the determination of FCEA and SCEA levels by electrochemiluminescence. We evaluated the diagnostic accuracy of FCEA and SCEA levels in early-stage CRC patients and healthy controls using ROC curve.

Results

A total of 298 people were included: 115 patients with CRC, 35 patients with adenomatous polyp (APC), 46 patients with non-gastrointestinal cancer (NGC), and 102 healthy controls (HC). The FCEA concentrations in CRC and APC patients were significantly higher than that of NGC and HC, and this is different from SCEA expression in APC and NGC. As a diagnostic biomarker of CRC, FCEA had significantly larger AUC compared with SCEA (.802 vs .735, P  < .001). For identifying early-stage colorectal cancer, FCEA showed better diagnostic efficacy (AUC: .831) than SCEA (AUC: .750), and the combination of the 2 biomarkers was even higher (AUC: .896). The sensitivity of FCEA was higher than that of SCEA (78.7% vs 29.8%). When SCEA was negative, 80.3% of CRC and 54.6% of APC cases could be identified by FCEA.

Conclusion

Compared with SCEA, FCEA has more advantages in the diagnosis of the early stage of colorectal cancer and adenomatous polyps.

Biologic markers in cancer diagnosis and treatment

We have reviewed several tumor markers that our advocates feel are now clinically useful, involve current assay technology, and are based on already available information. These include, in selected instances, estrogen receptors for breast cancer, thyrocalcitonin for medullary cancer of the thyroid, prostatic acid phosphatase for cancer of the prostate, alpha-fetoprotein for hepatocellular cancer, and carcinoembryonic antigen for monitoring colon cancer. We have considered the potential use of measurement of serum proteases and protein degradation products due to their activity as possible future areas of development, and we have explored measurement of tissue aryl hydrocarbon hydroxylase to identify populations at risk of cancer resulting from chemical carcinogenesis. It is clear that the study of tumor markers is already improving patient care in some specific areas and offers exciting potential for the future.

Further investigations of immunoreactive carcinoembryonic antigen (CEA) in colorectal cancer patients--with particular emphasis on the correlation between immunoreactive CEA levels in tissue, feces and blood

Immunoreactive carcinoembryonic antigen (IR-CEA) levels in colorectal cancer and mucosal tissues, feces and blood were measured in 14 colorectal cancer patients to study the correlation. IR-CEA levels in colorectal cancer tissues were about 30 times higher than those in colonic mucosal tissues. The correlation coefficient between IR-CEA levels in the tumor tissue and serum was 0.654 (p less than 0.02). We assumed that the total tumor IR-CEA levels were the product of the tumor IR-CEA level, by the estimated tumor weight. The correlation coefficient between the serum IR-CEA level and total tumor IR-CEA level was 0.750 (p less than 0.001). When the patients were divided into two groups with more and less a total tumor IR-CEA level of 65,000 ng, respectively, the statistical difference in serum IR-CEA levels was p less than 0.001. The differences in fecal IR-CEA levels between these two groups, however, are statistically insignificant (p less than 0.3). We assumed that there was a positive correlation between the IR-CEA levels in blood and tumor from the consideration that circulating IR-CEA originates from the metabolic imbalance of its production in colorectal cancer tissues over its degradation in the liver. Moreover, it is essential to consider that the fecal IR-CEA levels may be influenced by the following three factors: the intraluminal direct release of CEA from tumor, no degradation process of CEA in the gut lumen, and the intraluminal transport rate of colonic contents.