The Melbourne Colorectal Cancer Study: reflections on a 30-year experience.

This article reflects on 30 years of conducting the Melbourne Colorectal Cancer Study, a comprehensive, population-based investigation of colorectal cancer (CRC). The study had an incidence arm, a case-control arm and a survival arm, and contributed considerable knowledge about CRC risk, aetiology, prevention and screening. The incidence arm: confirmed high rates of CRC in Australia and the prevalent view that rates rise in first-generation immigrants from countries with low rates of CRC; and enabled the first report of high rates of colon cancer among Australian Jewish people and the first report of high rectal cancer rates anywhere. The case-control arm elicited: the contribution of family history, antecedent colorectal polypectomy and multiple antecedent stressful life events to CRC risk; the risk of rectal cancer in habitual beer drinkers; the first dietary risk score (emphasising the importance of a diet pursued over adult life that is high in foods of plant origin and fish, and low in fat and red meat); and the highly protective effect of regular aspirin use (stimulating much research globally, with the possibility of aspirin becoming an important preventive agent). The survival arm: found an adjusted CRC-specific 5-year survival rate of 42% among patients with CRC and 85% among matched control subjects; confirmed cancer stage as the most important single determinant of survival; and found that the survival rate among people with the earliest stage of CRC was only marginally lower than that of matched community control subjects, underlining the importance of early detection.