‘Research-based evaluation of the Norwegian Breast Cancer Screening Program Final Report’ from the Research Council of Norway.
‘The most important harm of the program is overdiagnosis’ says the report.
‘For each breast cancer death avoided approximately 5 are overdiagnosed.’
Although the report goes on to say, ‘However, an overdiagnosed breast cancer would be expected to need less aggressive treatment’ – it is well known that DCIS is often treated by mastectomy.
The report also explains why false negative mammograms and interval cancers are both potential harms of the screening programme and says ‘every fourth breast cancer diagnosed in women attending the program is an interval cancer’ (i.e.found between screenings), ‘of which approximately one third had a false negative mammogram from the previous screening round’ – so some women had postponed seeking help due to the previous negative mammogram.