RESUMO
BACKGROUND: communicating breast cancer screening (BCS) limits and overdiagnosis implies providing complete and balanced information to allow informed decision-making. OBJECTIVES: to describe women's perceptions, preconceptions, and information preferences regarding the breast cancer screening (BCS) programme paper and web information materials of the Agency for Health Protection of the Metropolitan Area of Milan (Lombardy Region, Northern Italy). DESIGN: qualitative, descriptive study. SETTING AND PARTICIPANTS: participants' voluntary recruitment took place in the registration departments of three hospitals. Participants were purposively recruited based on sociodemographic characteristics of the target population of the programme (44 women aged 40-74 years, living in the Metropolitan Area of Milan). In each material type subgroup, different health literacy levels and age classes were included, until thematic saturation was reached. MAIN OUTCOME MEASURES: thematic analysis of qualitative data collected during think-aloud interviews. RESULTS: the thematic analysis identified 5 main themes: 1. validation of the information reported in the materials, according to the interviewees' personal experiences;2. information preferences of particular subgroups of women, which led to a tailored approach for the web materials;3. negative emotions elicited while receiving information regarding BCS limits, which guided the rewriting of certain definitions; 4. disproportioned risk perception, with greater weight attributed to the risk of false negative results than the risk of overdiagnosis; 5. organizational preferences regarding the type and frequency of the provided tests and the age limits of the programme. CONCLUSIONS: in the present sample of women living in the Metropolitan Area of Milan, knowledge and comprehension of overdiagnosis are scarce. The main reasons for distrust in the BCS programme rely on the preexisting beliefs regarding the most appropriate tests and age limits. These beliefs were established from previously received information, inconsistent with that officially provided by the programme.