(ChemotherapyAdvisor) – Mammography has a limited impact on breast cancer mortality trends, according to a team of international researchers. This conclusion is based on a study entitled “Mammography Screening and Breast Cancer Mortality in Sweden,” which was in the Journal of the National Cancer Institute on July 17.

The investigators hypothesized that gradual implementation of breast cancer screening in Sweden would be reflected in county-specific mortality patterns. To test this hypothesis, the investigators used data from the Swedish Board of Health and Welfare from 1960 to 2009 to analyze breast cancer mortality trends in women aged 40 years and older.

The following results were reported. “From 1972 to 2009, breast cancer mortality rates in Swedish women aged 40 years and older declined by 0.98% annually, from 68.4 to 42.8 per 100 000, and it continuously declined in 14 of the 21 Swedish counties,” the investigators reported. “In counties in which screening started in 1974–1978, mortality trends during the next 18 years were similar to those before screening started, and in counties in which screening started in 1986–1987, mortality increased by approximately 12% (P=.007) after the introduction of screening compared with previous trends.” Finally, screening started 1987–1988 and in 1989–1990, mortality declined by approximately 5% (P=.001) and 8% (P<.001), respectively, after the introduction of screening.

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The investigators concluded that breast cancer mortality trends in Sweden are consistent with other studies that showed little or no impact of breast cancer screening on mortality rates.