A comparison of colorectal neoplasia screening tests: a multicentre community-based study of the impact of consumer choice.

OBJECTIVE: International guidelines and local practices for colorectal cancer screening suggest an important role for several different screening tests, and for consumer choice. We aimed to determine whether choice of test improved participation in screening.

DESIGN: A randomised comparative study offering one of six screening strategies: faecal occult blood testing (FOBT), FOBT and flexible sigmoidoscopy (FS), computed tomography colonography (CTC), colonoscopy, or one of two groups offered a choice of these strategies (one of which was sent an FOBT kit with the letter of invitation, while the other was required to request an FOBT kit by telephone if that was the test chosen).

SETTING AND PARTICIPANTS: 1679 people aged 50-54 or 65-69 years, randomly selected from the electoral roll in metropolitan Perth, Adelaide and Melbourne.

MAIN OUTCOME MEASURES: Participation, yield of advanced colorectal neoplasia (CRN), acceptability and safety.

RESULTS: 346 (20.6%) were excluded from screening, mostly for a recent examination (165), symptoms (72) or personal or family history of colorectal neoplasia or cancer (83). 278 of the 1333 eligible (20.9%; 95% CI, 18.7%-23.1%) participated in screening. Participation was similar by age and sex, but lower in Perth than Adelaide (17.1% v 24.2%; P = 0.01). Participation by screening group was: FOBT, 27.4%; FOBT/FS, 13.7% (P < 0.001 compared with FOBT); CTC, 16.3% (P = 0.005); colonoscopy, 17.8% (P = 0.02); or a choice of test 18.6% ("with FOBT kit"; P = 0.03) or 22.7% ("without FOBT kit"; P = 0.3). Yield of advanced CRN was higher in participants screened by colonoscopy than FOBT (7.9% v 0.8%; P = 0.02). All tests were well accepted and no serious complications arose from screening.

CONCLUSION: A choice of screening test did not improve participation. Participation by FOBT was higher than by other tests. Yield of advanced colorectal neoplasia on an intention-to-screen basis, determined by test sensitivity and participation, is likely to be a critical determinant of the effectiveness of screening strategies.