Hormone replacement therapy and false positive recall in the Million Women Study: patterns of use, hormonal constituents and consistency of effect.

Introduction: Current and recent users of hormone replacement therapy (HRT) have an increased risk of being recalled to assessment at mammography without breast cancer being diagnosed ('false positive recall'), but there is limited information on the effects of different patterns of HRT use on this. The aim of this study is to investigate in detail the relationship between patterns of use of HRT and false positive recall.

Methods: A total of 87,967 postmenopausal women aged 50 to 64 years attending routine breast cancer screening at 10 UK National Health Service Breast Screening Units from 1996 to 1998 joined the Million Women Study by completing a questionnaire before screening and were followed for their screening outcome.

Influence of personal characteristics of individual women on sensitivity and specificity of mammography in the Million Women Study: cohort study.

Objectives: To examine how lifestyle, hormonal, and other factors influence the sensitivity and specificity of mammography.

Methods: Women recruited into the Million Women Study completed a questionnaire about various personal factors before routine mammographic screening. A sample of 122,355 women aged 50-64 years were followed for outcome of screening and incident breast cancer in the next 12 months.