Oral Presentation Joint 2016 COSA and ANZBCTG Annual Scientific Meeting

Overdetection information in a breast cancer screening decision aid: Randomised controlled trial with 12-month follow-up (#123)

Jolyn Hersch 1 , Jesse Jansen 1 , Alexandra Barratt 1 , Les Irwig 1 , Nehmat Houssami 1 , Haryana Dhillon 1 , Kevin McGeechan 1 , Gemma Jacklyn 1 , Hazel Thornton 1 , Kirsten McCaffery 1
  1. School of Public Health, The University of Sydney, Sydney, NSW, Australia

Aims: Mammography screening reduces breast cancer mortality, but most women are unaware that it also leads to diagnosis and treatment of cancers that would never be clinically relevant (overdetection). We investigated the effects of including overdetection information in a breast screening decision aid.

Methods: We recruited a random cohort of NSW women aged 48-50 for a randomised controlled trial. Eligible women had not undergone mammography in the past 2 years and had no personal or strong family history of breast cancer. 879 women were randomised to receive either the intervention decision aid (evidence-based information on overdetection, breast cancer mortality reduction, and false positives) or a control decision aid (identical but without overdetection information). The primary outcome was informed choice (adequate knowledge, and consistency between attitudes and screening intentions) assessed via telephone interview about 3 weeks post-intervention. We assessed secondary outcomes by telephone at post-intervention (n=838), 6 months (n=790), and 12 months (n=746).

Results: More women made an informed choice in the intervention group (24%) than among controls (15%): difference 9% (95%CI 3%-14%); p<0.01. Compared with controls, more women in the intervention group had adequate knowledge (29% vs. 17%), fewer women expressed positive attitudes towards screening (69% vs. 83%), and fewer women intended to be screened (74% vs. 87%); all p<0.01. Knowledge and attitude differences persisted over 12 months. The intervention group had lower breast cancer worry than controls at each time-point (p<0.01; p=0.05; p=0.08). Fewer women underwent mammography within 6 months in the intervention group compared with controls (15% vs. 20%, p=0.06); by 12 months the groups equalised (both 29%).

Conclusions: Overdetection information improved women’s knowledge, shifted their attitudes, and increased the proportion of women making an informed choice about breast screening. Although the study groups differed in screening intentions post-intervention, mammography uptake over 12 months was comparable between groups.