PWE-338 Digital rectal examination: a discriminatory test in the diagnosis of colo rectal cancer: Abstract PWE-338 Table 1

Abstract

<h3>Introduction</h3> Rapid access clinics exist for patients who are symptomatic from symptoms suggestive of colorectal cancer. Eighty-five to 90% of such symptomatic patients have non- malignant pathology. This results in unnecessary and hurried use of expense resources. Working on the principle that colonic tumours bleed, an immunological faecal occult blood test (FOBTi) – which uses antibodies specific for human haemoglobin – can identify patients who may have colorectal cancer. <h3>Aim</h3> To determine the sensitivity and specificity of FOBTi in detecting patients with colorectal cancer (in the absence of covert per rectal bleeding) referred to rapid access colorectal clinics. <h3>Method</h3> A prospective cohort study was performed on patients referred to Rapid Access Colorectal clinic. A digital rectal exam (DRE) was performed on each patient and faecal sample obtained for FOBTi testing. Colonic investigations were arranged for each patient and results correlated to the FOBTi result. <h3>Results</h3> To date 107 FOBTi samples with complete colonic investigations are available. Twenty-seven patients tested FOBT positive, 81 FOBT negative. In the positive group, 44% had cancer (58% rectal cancer; 25% left sided cancer, 8% right sided cancer, 8% transverse colon cancer). Other diagnoses are shown below: In the FOBTi negative group no cancers were detected on further investigations. Using these results, FOBTi has a sensitivity of 100% and 84% specificity. The positive predictive value is 44% and negative predictive value 100%. <h3>Conclusion</h3> Immunological FOBTi is an instant and objective test which utilises immuno-chromatography to detect blood loss in the stool. When used with DRE in patients with clinical symptoms it has 100% sensitivity and 84% specificity. A negative result means patients are unlikely to have a cancer diagnosis, which may lead a reduction in unnecessary investigations. <h3>Disclosure of interest</h3> None Declared.