Home Forums Other Specialities Oncology OVERDIAGNOSIS IN SCREENING FOR BREAST CANCER.

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      Anonymous
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      Women’s perspectives on overdiagnosis in screening for breast cancer.

      Overview:
      In England, all women aged 50 and over are offered screening for breast cancer once every 3 years through the NHS Breast Screening Programme. In 2011–12, 1.7 million women aged 50–70 years were screened for breast cancer (Health and Social Care Information Centre 2013).
      The programme detected breast cancer in 13,619 women during this period, a rate of 7.9 cases per 1000 women screened. The programme is estimated to reduce the relative risk of death from breast cancer in women screened by 20% and to prevent around 1300 deaths from breast cancer in the UK each year (Independent UK Panel on Breast Cancer Screening 2012).

      A harmful effect of screening is overdiagnosis, in which a cancer detected on screening, and subsequently treated, would not have affected the woman’s health.
      An independent review estimated that around 4000 women in the UK are diagnosed each year with breast cancer that would not produce any symptoms in their lifetime, equivalent to roughly 3 cases of overdiagnosis for each death prevented (Independent UK Panel on Breast Cancer Screening 2012).
      The review group concluded that women should be offered clear information on the benefits and risks of breast cancer screening.

      New evidence:
      Hersch et al. (2013) used focus groups of women aged 40–79 to conduct a qualitative study of women’s responses to information about overdiagnosis in screening for breast cancer.
      Women in the suburbs of Sydney, Australia, who spoke fluent English and had never been diagnosed with breast cancer were randomly invited to participate. Each focus group (4–9 women) was given a presentation on mammography that outlined 3 published estimates of the rate of breast cancer overdiagnosis: 1–10%, 30% and 50%. Participants were then led through guided group discussions, which were transcribed and coded according to concept by two researchers.

      Of 118 women invited to participate, 50 from a range of socioeconomic backgrounds took part. The women had little prior knowledge of overdiagnosis in breast cancer screening, but the majority understood the concept by the end of the focus group.
      Responses to overdiagnosis varied from concern about the possibility of unnecessary treatment to viewing diagnosis of any cancer as a positive thing, irrespective of whether the disease would present in the patient’s lifetime.

      When considering whether the estimated risk of overdiagnosis would outweigh the benefits of screening, women considered the 1–10% estimate negligible and the 30% estimate acceptable. The 50% estimate, however, was seen as extremely high and some women said they would reconsider whether screening would be worthwhile at this level of risk.
      Most participants agreed that information about overdiagnosis of breast cancer with mammography should be available to women invited for screening.

      The authors concluded that women understand and value information on overdiagnosis in breast cancer screening but may change their views on screening on the basis of the level of risk.
      As such, the concept of overdiagnosis should be explained carefully to women to avoid influencing screening decisions in unexpected ways.

      Commentary:
      “These findings about women’s perspectives on the issue of overdiagnosis, and whether and how to communicate it, are highly opportune. Following the recent conference on preventing over diagnosis in Dartmouth, the USA, and with another meeting planned for Oxford in September 2014, the issue is gaining traction and policy priority in screening programmes.
      The views of the women in this study are relevant and valuable. However, there is possibility that participants may have picked up slightly sceptical views among the research team about the value of screening (given that the topic is being raised at all, participants could be forgiven for suspecting that the researchers could be doubtful). It is unsurprising that the issue of overdiagnosis was almost exclusively new to the study participants, who were from a range of socioeconomic backgrounds.

      “Informed consent is possible when people are able to understand, retain and weigh-up information provided for decision-making, and then communicate their decision to relevant parties (for example, clinicians or family). It is encouraging that most participants in this study expressed interest in being made more aware of overdiagnosis and demonstrated sufficient understanding to make informed personal decisions about whether to participate in mammography programmes. The data here indicate that informed consent is possible if information is made available to potential screening participants.

      “Supporting individuals to make decisions about participation in screening will always be an essential component of strategies to promote informed consent. Other elements to strategies – for example, promoting community level understanding and health literacy – could make interventions to support individuals in their decision-making more effective.” – Adrian Edwards, Cochrane Institute of Primary Care and Public Health, Cardiff University

      Study sponsorship: Informed Medical Decisions Foundation and the National Health and Medical Research Council of Australia.

      G Mohan.

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