Colonoscopy is empirically recommended as the first choice screening strategy in first-degree relatives of patients with colorectal cancer (CRC). However, this strategy is accepted by less than 40% of the risk population and two-thirds of screened individuals and renders a normal exploration. This pilot study assessed the accuracy of a latex agglutination immunochemical fecal occult blood test (LA-FOBT) for detecting advanced colorectal neoplasm (cancer or adenomatous polyps ≥1 cm in size, with villous pattern or high grade dysplasia) in asymptomatic first-degree relatives of patients with CRC.
One hundred and sixty-nine first-degree relatives of 135 index cases were prospectively included. All participants received a sensitive LA-FOBT (hemoglobin detection limit of 50 ng/ml buffer), and were invited to undergo colonoscopy. On the whole, 116 (69%) participants returned LA-FOBT and underwent colonoscopy.
LA-FOBT was positive in 19 of 116 (16%) cases. Colonoscopy detected neoplasms in 49 of 116 (42%) patients: 37 of 116 (32%) were nonadvanced adenomas and 12 of 116 (10%) advanced adenomas. LA-FOBT detected 10 of 12 (83%) advanced adenomas showing a sensitivity, specificity, positive predictive value, and negative predictive value of 83, 91, 53, and 98%, respectively. In patients with positive LA-FOBT, 1.9 colonoscopies were necessary for detecting one advanced adenoma, whereas in case of not performing this test 10 colonoscopies would be needed. Overall, approximately 80% of screening colonoscopies could be precluded using a LA-FOBT.
One-time screening with LA-FOBT successfully detects advanced colorectal adenomas and may save unnecessary colonoscopies in first-degree relatives of patients with CRC.
aDepartment of Gastroenterology
bResearch Unit, University Hospital of Canary Islands, La Laguna, Tenerife, Spain
Correspondence to Dr Enrique Quintero, MD, PhD, Department of Gastroenterology, University Hospital of Canary Islands, Ofra s/n.38320, La Laguna, Tenerife, Spain
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Received 18 October 2008 Accepted 7 January 2009