Colorectal cancer screening using stool DNA analysis in clinical practice: Early clinical experience with respect to patient acceptance and colonoscopic follow-up of abnormal tests

Background: Stool-based DNA screening for colorectal cancer (CRC) was recently made available for use in daily clinical practice (PreGen-Plus™). The main objectives of this study were to examine patients' screening experiences with stool DNA testing in routine clinical practice and the results of diagnostic colonoscopy in patients with an antecedent abnormal stool DNA test. Patients and methods: Patients undergoing stool-based DNA testing were asked to complete and return via mail an anonymous 10-item questionnaire inquiring about their test-related experiences. Colonoscopy findings for all abnormal stool-based DNA tests were ascertained via a telephone survey of the ordering primary care clinicians' offices. Results: Patient survey responses were collected between August 2003 and July 2005 and reflect an 18% (1211 of 6730) response rate. The majority reported that the specimen collection process was very easy/easy to perform (87%), that they were very likely/likely to use the test again (91%), and that they had never been screened for CRC previously by any method (52%). Tests were ordered predominantly by the patient's primary care clinician (90%), including obstetrician/gynecologist providers. Colonoscopy findings from 69 of 159 patients with an antecedent abnormal stool DNA test screened with PreGen-Plus™ between August 2003 and July 2004 were available for review. An abnormal stool DNA test correlated with a colonoscopically demonstrable abnormality in 49% of cases (34 of 69). Abnormal findings, including CRC in 3 patients (4%; 1 with Dukes A and 2 with Dukes B disease), single or multiple adenomatous polyps in 23 patients (33%), hyperplastic polyps in 3 patients (4%), and colitis in 5 patients (7%). Colonoscopy was reported as negative in 51% of patients (35 of 69), including 2 cases (3%) with an altered BAT-26 microsatellite caused by a normal polymorphism. Conclusion: Stool DNA testing provides an acceptable noninvasive alternative for CRC screening that can identify early-stage CRCs and adenomatous polyps in routine clinical practice. Ongoing and broader surveys are indicated to support these early findings.