Overdiagnosis in publicly organised mammography screening programmes: systematic review of incidence trends

Overdiagnosis is an identified problem of screening for breast cancer
as shown by Jørgensen et al.[1] However, there is another important
negative side effect of screening that is not highlighted very often.
When an abnormal screening mammogram turns out to be false-positive, this
can have a major impact on quality of life (QoL) and feelings of fear of
the woman concerned.

In the south of the Netherlands a multicenter, prospective
longitudinal study is running since 2002 concerning QoL in women with
breast cancer. Women are included when they have an abnormal screening
mammogram or a palpable lump. Questionnaires are completed before
diagnosis is known and then on 6 fixed moments after diagnosis and
possible treatment.
Between 2002 en 2007 385 women with an abnormal mammogram were included in
this study. Of these, 152 were diagnosed with breast cancer and 233 turned
out to have a false-positive screening mammogram. This means that 60.5%
of the women recalled after an abnormal mammogram turned out to have a
benign diagnosis.
To come to this benign diagnosis significantly more diagnostic procedures
were needed than to diagnose malignancy. Almost 50% of the women needed
more than 4 procedures, of whom 18 (8%) eventually needed an excisional
biopsy to come to the diagnosis.
QoL in these women was mainly influenced by their personality, and
especially women with an anxious personality showed a diminished QoL and
an increase in feelings of fear. The Eta squared for QoL was 0.27 and for
state anxiety 0.44 (Eta squared is the effect size; higher than 0.14 is a
large effect). The negative effects were observed for at least 1 year
after the false-positive mammogram.

Women often overestimate their risk of breast cancer and the benefits
of screening and are not aware of the possible dangers.[2] Thus, it seems
important to inform women correctly and abundantly about the pros and cons
of screening. However, a cross-sectional study of 27 websites by interest
groups in different countries found that the most important dangers of
screening – overdiagnosis and overtreatment – were the best-kept
secrets.[3]

Not only the possibility of overdiagnosis, and thus overtreatment,
should be mentioned in the information leaflets that accompany the
invitation for breast cancer screening, but also the consequences of being
recalled because of an abnormality on the mammogram, such as (extra)
diagnostic procedures or even surgery, and the significant possibility of
a decrease of QoL should not be left out.

References
1. Jørgensen KJ, Gøtzsche PC. Overdiagnosis in publicly organised
mammography screening programmes: systematic review of incidence trends.
BMJ 2009; 339: b2587. Doi: 10.1136/bmj.b2587

2. Nekhlyudov L, Li R, Fletcher SW. Information and involvement
preferences of women in their 40s before their first screening mammogram.
Arch Intern Med 2005;165:1370-4

3. Jørgensen KJ, Gøtzsche PC. Presentation on websites of possible
benefits and harms from screening for breast cancer: cross sectional
study. BMJ 2004;328:148-54

Competing interests:
None declared