Screening: Balancing the Benefits and Risks Ann Richardson

1. Screening: Balancing the Benefits and Risks Ann Richardson Wayne Francis Cancer Epidemiology Research Group

2. The aim of screening is to detect disease early, in order to improve the outcome for people with the disease.

4. Benefits:Harms: Extra years of life for some Earlier diagnosis but no extra people diagnosed by screening. years of life for some people. Simpler treatment for some Over-treatment of some people people with early disease. with early disease. Reassurance for those with False reassurance for those negative screen results. with false-negative results. Anxiety and sometimes physical harm for people with false-positive results. Benefits and harms of screening

5. Harms: Earlier diagnosis but no extra years of life for some people. Over-treatment of some people with early disease. False reassurance for those with false-negative results. Anxiety and sometimes physical harm for people with false-positive results. Benefits and harms of screening

6. “All screening programmes cause harm. Some do good as well.” (Muir Gray 1997)

7. The balance of benefit and harm of cancer screening may differ according to: • The screening test • The screening interval • The eligible age range • The quality of the screening programme • The type of cancer being screened for

8. 1. Cervical and bowel cancer Recognised premalignant phase, and effective treatment for pre-cancer Screening reduces incidence and mortality 2. Breast and prostate cancer Screening reduces mortality at the expense of overdiagnosis and increased incidence 3. Melanoma and thyroid cancer Screening increases incidence but has not been shown to reduce mortality (Forbes and Ramirez 2014, Esserman et al 2013) Are there three categories of cancer screening?

11. Surveys in Europe and the US suggest that most people overestimate the benefits of cancer screening • (Waller et al 2015, Gigerenzer et al 2009, Schwartz et al 2004)

12. People differ in how they weigh up the benefits and harms of screening, including their willingness to accept overdiagnosis in cancer screening. (Van den Bruel et al 2015, Plumb et al 2014)

18. What is the best way to provide accurate information about the benefits and risks of cancer screening, so people can make an informed choice about whether to participate? The challenge

19. “There is a responsibility to effectively communicate all relevant information to people who are invited to participate in a screening programme so they are able to make an informed decision about whether to take part.” Judi Strid and Betsy Marshall, 2006