Early detection or prevention?: What is the main aim of different cancer screening programmes?

by Amanda Chorley and Jo Waller

Cancer screening programmes, such as breast, cervical, and bowel, are an important tool in the fight against cancer. Many people are aware of the value of early detection of cancer, which breast screening and the Faecal Occult Blood test (FOBt) part of bowel screening offer, which allows for treatment at an earlier stage when it is more likely to be effective. But are people aware that cervical screening and bowel scope screening (also known as flexible sigmoidoscopy, or FS) primarily aim to prevent cancer by identifying and removing abnormalities which may progress into cancer at a later date? This is the question we looked to answer in our recently published paper¹ in the Journal of Medical Screening.

As part of a larger survey on attitudes and behaviours surrounding cancer, we asked 1433 middle aged and older adults what they thought the main purpose of each of these screening programmes was. We found that while the majority of respondents were aware that breast screening (77.9%) and FOBt (73.2%) aimed to detect cancer early, only 17.6% knew that cervical screening primarily aimed to prevent cancer. For bowel scope screening the figure was only 13.8%. Overall only 13 people correctly identified the purpose of all four screening programmes, which is just under 1% of respondents.

We also looked at whether people had participated in each programme in the past to see whether that had any effect on awareness of the purpose of the programme. People who had been sent a test kit, and those who had completed and returned the kit were more likely to know that FOBt is designed to detect cancer early. For breast screening, only those having participated in screening were more likely to know that it was aimed at early detection. Having received an invitation did not seem to have an effect on knowledge of the purpose of the test.

However for both cervical screening and bowel scope screening neither those who had received an invitation nor those who had actually participated in the programme were any more likely to be aware of the preventive nature of the programme than respondents who hadn’t been invited or participated. This is despite the leaflets accompanying invitations clearly stating prevention as the main purpose.

On the one hand it is positive that public health messages on the importance of the early detection of cancer have been so effective, and that the majority of people recognise this to be the purpose of breast screening and FOBt. However, for people to make an informed choice about whether to participate in a screening programme they need an understanding about what the screening test aims to do, as well as any risks and benefits. Our survey suggests that this is not the case for cervical screening and bowel scope. As well as this lack of awareness being an issue for informed choice, it could also have consequences for how people engage with the screening programmes. People may end up avoiding screening tests if they are afraid they might be told they have cancer^{2, 3}. Knowing that some programmes can prevent cancer by finding and removing abnormalities may help to reduce these fears. Other studies have shown that women invited to colposcopy after having an abnormal result from their smear test sometimes mistakenly believe they have cancer^{4, 5}. A better awareness that cervical screening mainly looks for cell abnormalities which can be removed before they have a chance to turn into cancer may help in reducing stress and worry about the abnormal result.

If leaflets aren’t getting these messages across effectively, one of the priorities for the future will be finding different ways to communicate about cancer screening so that everyone understands what the tests are trying to do.

 

1. Chorley AJ, Hirst Y, Vrinten C, Wagner Cv, Wardle J and Waller J. Public understanding of the purpose of cancer screening: A population-based survey. J Med Screen. 2017; 0: 0969141317699440.
2. Vrinten C, Waller J, von Wagner C and Wardle J. Cancer fear: facilitator and deterrent to participation in colorectal cancer screening. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2015; 24: 400-5.
3. Andersen MR, Smith R, Meischke H, Bowen D and Urban N. Breast cancer worry and mammography use by women with and without a family history in a population-based sample. Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology. 2003; 12: 314-20.
4. Kavanagh AM and Broom DH. Women’s understanding of abnormal cervical smear test results: a qualitative interview study. BMJ (Clinical research ed). 1997; 314: 1388.
5. Gray NM, Sharp L, Cotton SC, et al. Psychological effects of a low-grade abnormal cervical smear test result: anxiety and associated factors. British journal of cancer. 2006; 94: 1253-62.