Population-based screening is an organised, systematic and integrated process of testing for signs of cancer or pre-cancerous conditions in populations without obvious symptoms. Programs target specific populations and/or age groups where evidence shows screening to be most effective.
In Australia, there are national population-based screening programs for breast, cervical and bowel cancers. The programs are run through partnerships between the Australian Government and state and territory governments and aim to reduce illness and death through early detection of cancer or pre-cancerous abnormalities.
BreastScreen Australia, established in 1991, provides free, 2-yearly screening mammograms to women aged 40 and over, and actively targets women aged 50–74. BreastScreen Australia aims to reduce morbidity and mortality from breast cancer by using screening mammograms to detect unsuspected breast cancers in women with no symptoms. Finding breast cancer early often means that the cancer is small, which is associated with increased treatment options and improved survival.
Screening mammograms work well in older women as breasts become less dense as women get older. 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.
However, even though screening mammography is not recommended for women under the age of 40, young women can still develop breast cancer. Therefore, it is important for women of all ages to be aware of how their breasts normally look and feel and promptly report any new or unusual changes to their general practitioner.
The National Cervical Screening Program, established in 1991, targets women aged 25–74 for a 5-yearly Cervical Screening Test. The National Cervical Screening Program aims to detect and treat abnormalities while they are in the precancerous stage, before any possible progression to cervical cancer.
It has been recognised for some time that cervical cancer is a rare outcome of persistent infection with one or more oncogenic (cancer-causing) types of human papillomavirus (HPV). In Australia, primary prevention of cervical cancer is through vaccination against HPV through the National HPV Vaccination Program and secondary prevention is through the National Cervical Screening Program.
The National Bowel Cancer Screening Program, established in 2006, offers free 2-yearly screening for all Australians aged 50–74, inviting them to screen for bowel cancer using a free faecal occult blood test.
Bowel cancer can develop without any early warning signs. Most bowel cancers develop from benign polyps and adenomas over several years before spreading to other parts of the body. Often very small amounts of blood leak from these growths and pass into the bowel motion before any symptoms are noticed. An immunochemical fecal occult blood test (commonly known as an iFOBT) is a non-invasive test which detects microscopic amounts of blood in the bowel motion, thus flagging potential bowel abnormalities at an early stage. The NBCSP invites people to complete an iFOBT in their own home and send their completed iFOBT to the program’s pathology laboratory for analysis. People with blood detected in their bowel motion are advised to consult their general practitioner to discuss further testing. In most cases this will involve a specialist looking inside the bowel using a special instrument. This procedure is known as a colonoscopy.
Measures of participation in cancer screening programs tell us how many people participate in these programs, and whether factors such as remoteness, socioeconomic area or Indigenous status mean that people are more or less likely to miss out on the benefits of screening. High participation in cancer screening programs is needed to gain the greatest benefits in terms of reducing illness and death from these cancers.
The Australian Institute of Health and Welfare (AIHW) publishes annual reports that monitor data for each of the 3 screening programs based on key performance indicators.
More than 5.2 million cervical screening participants aged 25–74 in 2018–2022
Cervical screening HPV test positivity was 10% in 2022
In 2020–2021, around 1.7 million women participated in the BreastScreen Australia. This was 48% of women aged 50–74
40.9% of the 6.1 million people invited to screen between January 2020 and December 2021 participated in the NBCSP
74% of people who have previously participated in the NBCSP participated again in 2020–2021
Screen-detected bowel cancers less likely to cause death than bowel cancers diagnosed in people never invited to screen