The findings are based on a study conducted by the Research Council of Norway — upon request by the Ministry of Health and Care Services — to evaluate the country's Breast Cancer Screening Programme amidst debate on the wisdom of offering periodic screenings.
The evaluation was led by Professor Roar Johnsen of the Norwegian University of Science and Technology. Together with NTNU postdoctoral fellow Signe Opdahl and the rest of the steering committee, they reviewed all studies done on mammograms in Norway since 2008. The team found inconsistencies in the results of these studies. One report shows that mammograms have reduced the number of cancer deaths by 10 percent, while another claims as much as 36 percent.
From their evaluation, Prof. Johnsen's team made the following conclusions:
- Norway's breast cancer mortality has been reduced by about 20-30 percent as a result of the screening programme.
- The screening results in overdiagnosis of 15-20 percent.
- For every 27 women who avoid dying of breast cancer, 142 women are overdiagnosed and treated unnecessarily.
- There are a lot of uncertainties in these numbers, because the studies that the evaluation looked at are all very different, and because factors such as the use of mammograms at private clinics and hormone treatment during menopause are things that most studies have not been able to consider.
- From a social perspective, the balance between cost and effect is within the level that health authorities consider to be acceptable for healthcare services.
“The goal of the Breast Cancer Screening Programme was to reduce breast cancer mortality rates by 30 percent. Depending on how you look at it, our estimates show that this goal may have been reached. But it has taken a huge toll in the form of overdiagnosis,” said Prof. Johnsen.
About three quarters of women between 50 and 69 years of age choose to participate in the screening programme, and the Norwegian government spends NOK 574 million per screening round to check these women for breast cancer.
"More money should be given to research so that we have more knowledge about which tumours do and do not need treatment," Prof. Johnsen noted. "Each individual woman needs to consider the pros and cons from her side when she decides if she wants to participate in the Breast Cancer Screening Programme.”
The evaluation was given to the Norwegian Minister of Health and Care Services Bent Høie on 5 June. “We have now presented the basis for a political decision,” Prof. Johnsen added.
Source: Norwegian University of Science and Technology (NTNU)
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