Regular mammograms may decrease the risk for deadly breast cancer by 49%, a new case-control study suggests.
According to the Dutch investigators, the greatest reduction occurred in women aged 70 to 75 years and represented a drop of 84%.
“Our study adds further evidence that mammography screening unambiguously reduces breast cancer mortality,” said senior researcher Suzie Otto, PhD, from the Department of Public Health at Rotterdam’s Erasmus Medical Centre, the Netherlands, in a news release.
The study was published online December 6 in Cancer Epidemiology, Biomarkers, and Prevention.
For the study, investigators examined data from 755 women aged 49 to 75 years who died of breast cancer from 1995 to 2003, and matched them closely by age and screening occurrence with 3739 control patients (5 per case).
Of the cancers detected, 29.8% were detected by screening mammogram, 34.3% were detected at intervals between screenings, and 35.9% occurred in women who had never been screened (nonparticipants).
Cancers in nonparticipants tended to be more advanced, with a rate of 29.5% for stage IV tumors compared with 5.3% for screen-detected cases and 15.1% for interval cases.
In contrast, regular screening was more likely to reveal early-stage localized tumors (34.2% vs 10.8% for intervals and 10.3% for nonparticipants).
As a result, women who had undergone 3 or more mammography screenings were 49% less likely to die from breast cancer on detection, relative to control patients (odds ratio [OR], 0.51; 95% confidence interval [CI], 0.40 – 0.66).
Although the greatest effect was observed among women aged 70 to 75 years (84% decrease; OR, 0.16; CI, 0.09 – 0.29), the decrease in breast cancer mortality risk for the target population aged 50 to 69 years remained significant (39%; OR, 0.61; 95% CI, 0.47 – 0.79).
The authors note that these benefits may be duplicated in the United States with the presence of a government-funded program that encourages a preventive medicine approach.
In the Netherlands, mammography screening is offered free of charge to women aged 50 to 75 years. The program is carried out by regional organizations that personally invite eligible women by mail to a fixed appointment at a mobile screening unit.
“The Dutch government considers it imperative that everyone eligible for a screening program is given the opportunity to participate,” Dr. Otto noted in the release, noting that the commensurate decrease in breast cancer mortality rates has been replicated in Europe and Australia.
The study was supported by the Dutch Health Care Insurance Council and the National Institute for Public Health and the Environment. The authors have disclosed no relevant financial relationships.
Cancer Epidemiol Biomarkers Prev. Published online December 6, 2011. Abstract
— Yael Waknine
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