Worldwide, colorectal cancer (CRC) is a significant health burden with over one million persons diagnosed annually . The five-year survival rate for localised disease is high, yet few CRCs (less than 40%) are detected at this stage . Many CRC deaths are preventable as screening can reduce incidence through the identification and removal of precancerous polyps [3, 4] and increase early detection of disease [5, 6]. Australian National Health and Medical Research Council (NHMRC) screening guidelines  recommend that asymptomatic persons “at or slightly above average risk” receive either FOBT screening biennially or sigmoidoscopy (preferably flexible) every five years commencing at age 50 years . For persons at “moderately increased risk”, colonoscopy is endorsed every five years starting at age 50 or at an age ten years younger than the age of first diagnosis of bowel cancer in the family, whichever comes first . Endoscopy screening for persons at “potentially high risk” is recommended at least on a five-yearly basis in the NHMRC screening guidelines. However, age at screening commencement, test type and repeat testing interval are dependent on the type of family-specific mutation identified .
Australia’s National Bowel Cancer Screening Program
In Australia, Medicare administers the National Bowel Cancer Screening Program (NBCSP) Register . Medicare selects eligible participants from either the Medicare enrolment records or the Department of Veterans’ Affairs . The NBCSP Register is responsible for mailing of screening invitations and FOBT kits, the recording of participants’ details and the issuing of reminder letters . As part of the NBCSP, participants are encouraged to nominate their usual primary care provider on their participants details form; however, this is not compulsory . The recently re-funded NBCSP offers persons turning 50, 55 and 65 years of age via mail a one-off immunochemical Faecal Occult Blood Test (FOBT) screening invitation . It is important to note that the limited format of the NBCSP (restriction of screening to persons in selected age brackets across the at-risk population),  is not consistent with the NHMRC recommendation of biennial FOBT screening of all Australians in the at-risk population . A recent study examining the costs and outcomes from full (rather than limited) implementation of a biennial FOBT screening for adults in the at-risk population (50–74 years) identified a likely mortality reduction of 25% and saving of 500 deaths per year .
Screening participation in Australia
Participation rates in Australia’s NBCSP appear to have reached a plateau since the pilot program’s introduction [9, 11–13]. The pilot program received a response rate of 45%, with the roll-out of the NBCSP (with screening offered to persons 50 and 65 years of age) in 2006 receiving a slightly lower rate of 41% . The rate of participation only marginally increased in 2008 to 42.9% when the program widened to offer screening to persons aged 55 years of age . Most recent estimates suggest a similar rate of low participation (40.1%) . The experience in other countries with national screening programs offering repeated FOBT screening to a wider section of the at-risk population suggests that much higher screening rates are achievable. For example, FOBT screening rates in the United Kingdom and Finnish screening programs are currently 52% and 71% respectively [14, 15]. In Australia, previous community- based evaluations have also indicated low rates of CRC screening, with 5 to 20% of individuals ever undertaking FOBT [16–18]. The most recent assessment in New South Wales (NSW) indicated that 18% of persons aged over 50 years had undertaken FOBT in the previous five years . In relation to colonoscopy screening in Australia, two population-based assessments in NSW have suggested under screening among persons at elevated levels of risk [16, 19].
Given low rates of CRC screening, it is important to identify factors which may influence screening uptake. Previous studies have indicated that the following factors influence CRC screening behaviour: socio-demographic characteristics (e.g. older age, higher education, higher income); lifestyle factors (e.g. smoking history, chronic disease); family history (e.g. personal or family history of CRC); awareness (e.g. knowledge of CRC and perceived risk of developing CRC) and health care utilisation (e.g. usual source of care, number of GP visits, and health care coverage) [20–26]. In the Australian context, a small number of studies have explored determinants of CRC screening uptake [17–19, 27, 28] with little known about predictors of screening behaviour for persons at varying levels of risk . Since the introduction of the NBCSP in 2006, no community- or population-based assessments in Australia have been conducted. Recent evidence pertaining to FOBT screening uptake and inequalities in participation have been confined to annual NBCSP monitoring reports, which report screening rates among a limited section of the at-risk population (persons 50, 55 and 65 years of age) [9, 11–13]. Further, since the NHMRC guidelines’ implementation in 1999, only one study has assessed the predictors of risk-appropriate screening for persons at each level of risk in accordance with guideline-recommendation . The identification of factors associated with risk-appropriate screening is of critical importance for future planning and implementation of tailored CRC screening programs.
This study aimed to assess among a large community-based cohort of at-risk persons (aged 56–88 years), the factors associated with: (1) ever receiving any CRC testing; (2) receiving screening in accordance with screening guidelines; and (3) recent use of colonoscopy screening.