Web update: Participation in national cancer screening programs in 2014–2015 presents statistics about participation rates in Australia’s three national cancer screening programs: the National Bowel Cancer Screening Program, BreastScreen Australia and the National Cervical Screening Program. Participation rates are presented for the 31 Primary Health Network (PHN) areas and for more than 300 smaller local areas called Statistical Areas Level 3 (SA3s), as defined by the Australian Bureau of Statistics (ABS).
This technical note summarises indicator specifications and methods used to calculate results presented in the Web update: Participation in national cancer screening programs in 2014–2015 on www.myhealthycommunities.gov.au.
National cancer screening programs
Population-based screening is an organised, systematic and integrated process of testing for signs of cancer or precancerous conditions in asymptomatic populations. Australia has three national cancer screening programs:
- National Bowel Cancer Screening Program
- BreastScreen Australia
- National Cervical Screening Program
Population-based screening programs aim to reduce death and illness by using screening tests to detect unsuspected cancers or precancerous conditions in persons who have no symptoms and therefore would not otherwise know they had the disease. Detection of cancer or precancerous conditions at an early stage allows access to diagnostic and treatment services early, so that individuals can benefit the most from available treatments.
In Australia, screening services through the three national cancer screening programs are provided free to individuals in the target population (for bowel and breast screening), or are covered by a Medicare rebate (for cervical screening).
The National Bowel Cancer Screening Program
In Australia, population-based bowel cancer screening is available through the National Bowel Cancer Screening Program (NBCSP). The NBCSP started in 2006 and is managed by the Australian Government Department of Health in partnership with state and territory governments. The goal of the NBCSP is to reduce death and illness associated with bowel cancer by actively recruiting and screening the target population for early detection or prevention of the disease.
The Clinical practice guidelines for the prevention, early detection and management of colorectal cancer, endorsed by the National Health and Medical Research Council (NHMRC), recommend that bowel cancer screening for the asymptomatic Australian population begin at age 50.1 The program’s approach to invite eligible persons (invitees) aged between 50 and 74 to screen is consistent with other international bowel cancer screening programs.
In 2014–2015, the NBCSP offered people aged 50, 55, 60, 65, 70 and 74 free screening with an immunochemical Faecal Occult Blood Test (iFOBT). An iFOBT is a non-invasive test that can detect microscopic amounts of blood in a bowel motion, which may indicate a bowel abnormality such as an adenoma or cancer. The NBCSP participation rate is defined as the percentage of people invited to screen in a 24-month period who returned a completed screening test within the defined 24-month period or in the following six months, excluding those who opted off or suspended from the program without completing the test.
In Australia, population-based breast cancer screening is available through BreastScreen Australia, which targets women aged 50–74 for two-yearly screening mammograms (women aged 40–49 and 75 and older are also eligible to attend, but are not actively targeted). In screening mammography, two views are taken of each breast and the images reviewed by radiologists for suspicious characteristics that require further investigation.
Screening mammograms work well in older women because breasts become less dense as women get older, particularly after menopause, which is why mammograms become more effective as women get closer to age 50. Mammographic screening is not recommended for women younger than 40. This is because breast tissue in premenopausal women tends to be dense, which can make it difficult to correctly identify the presence of breast cancer with mammography.
Participation is a major indicator of the performance of BreastScreen Australia, because high attendance for screening by women in the target age group maximises the reduction in mortality from breast cancer. Participation is measured as the percentage of women in the population aged 50–74 screened by BreastScreen Australia over two calendar years.
The National Cervical Screening Program
In Australia, primary prevention of cervical cancer is through vaccination against the human papillomavirus (HPV), which is the primary underlying cause of cervical cancer. Secondary prevention is by cervical screening, through the National Cervical Screening Program (NCSP), to detect and treat abnormalities while they are in the precancerous stage, prior to any possible progression to cervical cancer. Detection of precancerous abnormalities through cervical screening uses cytology from the Papanicolaou smear, or ‘Pap test’, as the screening test.
Participation is a major indicator of the performance of the NCSP, measured as the percentage of women in the population aged 20–69 who had at least one Pap test over two calendar years.
Presentation of results
The web update presents information at the geography of:
- Primary Health Network (PHN) areas – 31 geographic areas covering Australia, with boundaries defined by the Australian Government Department of Health
- Statistical Areas Level 3 (SA3s) – 333 geographic areas covering Australia, with boundaries defined by the ABS.2
National participation rates for each of the three cancer screening programs are also included for context.
For National Bowel Cancer Screening Program data, PHN areas and SA3s were assigned to invitees using Statistical Area Level 1 (SA1) to PHN area and SA1 to SA3 correspondences. Those invitees without reliable SA1 details were mapped with postcode to PHN and SA3 correspondences instead.
For BreastScreen Australia and National Cervical Screening Program data, PHN areas and SA3s were assigned to women in the respective datasets using postcode to PHN and postcode to SA3 correspondences.
Where a postcode or SA1 boundary overlapped PHN areas or SA3 boundaries, the relevant records were attributed based on the percentage of the population within that postcode or SA1 that fell within the PHN area or SA3. Figures were rounded at the end of the calculations to avoid truncation error.