Japan colorectal tumor prevention study: clinical trial by low-dose aspirin

Interventions: aspirin enteric-coated tablet (100 mg, one tablet daily) for four years
Primary outcome(s): The primary endpoint is set as the incidence of newly diagnosed colorectal Index Lesion (adenomas >= 10 mm in diameter, adenomas with high-grade dysplasia, or invasive cancer) during 4 years observation excluding the first year observation.
Study Design: Single arm Non-randomized