ArticleBMC cancer2013
Overdiagnosis of breast cancer in the Norwegian Breast Cancer Screening Program estimated by the Norwegian Women and Cancer cohort study.
Article in BMC cancer, 2013. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers, 2 of them syntheses that pooled it.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
5 citing papers in PubMed, 2 syntheses or guidelines pooled it.
- Recommendations on screening for breast cancer in women aged 40-74 years who are not at increased risk for breast cancer.CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne · 2018Guideline
- Breast Cancer Screening Programmes across the WHO European Region: Differences among Countries Based on National Income Level.International journal of environmental research and public health · 2017Pooled it
- Menopausal hormone therapy and breast cancer risk: effect modification by body mass through life.European journal of epidemiology · 2019Article
- Benefit-to-harm ratio of the Danish breast cancer screening programme.International journal of cancer · 2017Article
- Mammography screening in three Finnish residential areas: comprehensive population-based study of breast cancer incidence and incidence-based mortality 1976-2009.British journal of cancer · 2015Article
Corrections and comments
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Authors and funding
4 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundThere is increasing ambiguity towards national mammographic screening programs due to varying publicized estimates of overdiagnosis, i.e., breast cancer that would not have been diagnosed in the women's lifetime outside screening. This analysis compares the cumulative incidence of breast cancer in screened and unscreened women in Norway from the start of the fully implemented Norwegian Breast Cancer Screening Program (NBCSP) in 2005.
methodsSubjects were 53 363 women in the Norwegian Women and Cancer (NOWAC) study, aged 52-79 years, with follow-up through 2010. Mammogram and breast cancer risk factor information were taken from the most recent questionnaire (2002-07) before the start of individual follow-up. The analysis differentiated screening into incidence (52-69 years) and post screening (70-79 years). Relative risks (RR) were estimated by Poisson regression.
resultsThe analysis failed to detect a significantly increased cumulative incidence rate in screened versus other women 52-79 years. RR of breast cancer among women outside the NBCSP, the "control group", was non-significantly reduced by 7% (RR=0∙93; 95% confidence interval 0∙79 to 1∙10) compared to those in the program. The RR was attenuated when adjusted for risk factors; RRadj=0∙97 (0∙82 to 1∙15). The control group consisted of two subpopulations, those who only had a mammogram outside the program (RRadj =1∙04; 0∙86 to 1∙26) and those who never had a mammogram (RRadj=0∙77; 0∙59 to 1∙01). These groups differed significantly with respect to risk factors for breast cancer, partly as a consequence of the prescription rules for hormone therapy which indicate a mammogram.
conclusionsIn the fully implemented NBCSP, no significant difference was found in cumulative incidence rates of breast cancer between NOWAC women screened and not screened. Naïve comparisons of screened and unscreened women may be affected by important differences in risk factors. The current challenge for the screening program is to improve the diagnostics used at prevalence screenings (ages 50-51).
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