Should We Adjust Visually Assessed Mammographic Density for Observer Variability?
This study aimed to determine whether correcting for observer variability alters estimations of breast cancer risk associated with mammographic density. A case control design examined the relationship between mammographic density, measured by visual analogue scales (VAS), and the risk of breast cancer after correcting for observer variability. Mammographic density was assessed by two observers and average scores (V2) were adjusted to correct for observer variability (V2ad). Two case-control sets were identified: (i) breast cancer detected during screening at entry and (ii) breast cancer detected subsequently. Cases were matched to three controls. In the first case-control set the odds ratio for breast cancer was 4.6 (95 %CI 2.8–7.5) for the highest compared to the lowest quintile of V2, and was attenuated for V2ad (OR 3.1, 95 %CI 1.9–4.8). Similar findings were observed for the second case-control set. Not adjusting for observer variability may lead to an overestimate of the risk of breast cancer.
KeywordsDigital Mammogram Breast cancer Visual analogue scales (VAS) Observer bias Case-control study
We acknowledge the support of the National Institute for Health Research (NIHR) and the Genesis Prevention Appeal for their funding of the PROCAS study. We would like to thank the women who agreed to take part in the study and the study staff for recruitment and data collection. This paper presents independent research funded by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research programme (reference number RP-PG-0707-10031: “Improvement in risk prediction, early detection and prevention of breast cancer”). The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, or the Department of Health.
- 1.Duffy, S.W., Nagtegaal, I.D., Astley, S.M., Gillan, M.G., McGee, M.A., Boggis, C.R., Wilson, M., Beetles, U.M., Griffiths, M.A., Jain, A.K., Johnson, J., Roberts, R., Deans, H., Duncan, K.A., Iyengar, G., Griffiths, P.M., Warwick, J., Cuzick, J., Gilbert, F.J.: Visually assessed breast density, breast cancer risk and the importance of the craniocaudal view. Breast Cancer Res. 10(4), R64 (2008)CrossRefGoogle Scholar
- 3.Evans, D.G.R., Warwick, J., Astley, S.M., Stavrinos, P., Sahin, S., Ingham, S., McBurney, H., Eckersley, B., Harvie, M., Wilson, M., Beetles, U., Warren, R., Hufton, A., Sergeant, J.C., Newman, W.G., Buchan, I., Cuzick, J., Howell, A.: Assessing individual breast cancer risk within the U.K. National Health Service Breast Screening Program: a new paradigm for cancer prevention. Cancer Prev. Res. 5(7), 943–951 (2012)CrossRefGoogle Scholar
- 4.R Core Team: R: a language and environment for statistical computing. In: R Foundation for Statistical Computing, Vienna, Austria (2012). ISBN: 3-900051-07-0. http://www.R-project.org/