Comparative Evaluation of Colon Cancer Specific Antigen-2 Test and Chromocolonoscopy for Early Detection of Egyptian Patients with Colorectal Cancer.

Background: Effective screening of colorectal cancer (CRC) in early stage could reduce the advancement of CRC and therefore mortality. Effective screening is based on either stool dependent tests or colon dependent examination.

Aims: The aim of the study was a comparative evaluation of chromocolonoscopy and Colon Cancer-Specific Antigen-2 test for early detection of colorectal cancer in Egyptian patients.

Methods: This case control study was carried out on 55 patients classified into 3 groups: Group I consisted of twenty patients with precancerous lesions detected by colonoscopy, Group II consisted of twenty patients diagnosed with colorectal cancer and Group III consisted of fifteen individuals (who underwent colonoscopy for other indications) as a control group. All the subjects were subjected to measure occult blood in the stool, measurement of Colon Cancer-Specific Antigen-2 level in serum and tissue and chromo colonoscopy using Indigo Carmine stain.

Results: In group II, there was a statistically significant increase in CCSA2 in serum as compared to the other 2 groups. Cutoff >11.3 CCSA2 in serum showed 65% sensitivity, 85% specificity, 81.2% PPV, 70.8% NPV and 70.3% accuracy in the differentiation of group II with cancer colon from group I with premalignant colonic lesions. A cutoff > 9.1 CCSA2 in serum showed 95% sensitivity, 46.67% specificity, 70.4% PPV, 87.5% NPV and 73.5% accuracy in differentiating group II with cancer colon from normal controls (group III).

Conclusion: CCSA-2 level in serum was significantly higher in cancer colon. Chromoendoscopy has a role in the detection of polyps, both neoplastic and non-neoplastic.