P-236 Screening Practices of Australians at Population and Familial Risk Following the Partial Roll-out of the National Bowel Cancer Screening Program, 2009-2012

Introduction: Australia has one of the highest incidences of colorectal cancer (CRC) in the world. In 2006, a partial roll-out of the national bowel cancer screening program (NBCSP) using faecal occult blood testing was introduced, with free screening offered to a small proportion of the eventual target of all 50-74 year olds biennially. The complete roll-out is due in 2020. We aimed to estimate CRC screening practices and their consistency with national screening guidelines recommendations from 2009-2012, approximately midway through the introduction of the program. Methods: Cohort participants of the Australasian Colon Cancer Family Registry completed a questionnaire on family history and reported colorectal cancer screening in the past five years. Based on their family history of CRC, 1827 were categorised as ‘at or slightly above average risk’, ‘moderately increased risk’, or ‘potentially high risk’ according to the Australian National Health and Medical Research Council (NHMRC) guidelines. Based on their reported mode and frequency of screening, we calculated the proportions of participants who were under- and over-screening according to the NHMRC guidelines. We performed logistic regression analysis to evaluate associations between the participants' sociodemographic characteristics and screening participation. Results: Of 301 participants classified at ‘at or slightly above average risk’ of CRC, 188 (62%) were not screening, 13 (4%) were under-screening, 40 (13%) were appropriately screening, and 60 (20%) were over-screening (mainly by colonoscopy). Of 1006 participants at moderately increased risk, 629 (63%) were not screening, 6 (1%) were under-screening, 278 (28%) were appropriately screening, and 93 (9%) were over-screening. Of 520 participants at potentially high risk, 289 (55%) were not screening, 38 (7%) were under-screening, 193 (37%) were appropriately screening, and 0 (0%) were over-screening. Of the participants categorised ‘at or slightly above average risk’ of CRC, middle-aged participants (40 to 59 years), those with a family history of CRC (defined as one first-degree relative diagnosed after age 50) and those with tertiary education were more likely to be over-screening. For participants categorised at ‘moderately increased risk’ or ‘potentially high risk’ of CRC, middle-aged participants, those with tertiary education and those who had resided in Australia longer (≥20 years vs. <20 years) were more likely to engage in appropriate screening. Conclusion: Overall, across all risk categories, appropriate CRC screening participation levels during the partial roll-out of the NBCSP were low, but participation levels were an order of magnitude higher compared with the same cohort a decade ago and prior to the NBSCP. The proportion of people receiving appropriate screening was lower than the proportion under-screening or not screening. This suggests that guidelines for CRC screening are not being well implemented in the population. Substantial over-screening was occurring and most evident among middle-aged, tertiary educated and long-term Australian residents. Our research supports more effective strategies to improve screening participation for all individuals appropriate to their risk.