A study found that mammograms don’t always deliver the result that women want. Mammograms tend to find more small cancers, but don’t lower a woman’s risk of dying of breast cancer.
The study analyzed data from 547 U.S. counties that reported the percentage of women over the age of 40 who had had a mammogram between 1998 and 2000.
The results of the study were reported in JAMA Internal Medicine. The authors of the study assert that the most prominent effect of screening mammography is over diagnosis.
More than 16 million women lived in those counties and 53,207 were diagnosed with breast cancer in 2000.
The study also found that over the subsequent 10 years, 15% of the women died of breast cancer.
From county-to-county, the variation in the number of women who received screening mammograms ranged from 38% to 78%.
This study found that the belief that counties with better screenings would have fewer breast cancer deaths is a misconception.
Researchers assert that the risk of death from breast cancer over 10 years was essentially equivalent.
Although the scanning did find more cancers, for every 10% increase in screening, the number of cancer found increased by 16%.
The increased screening identified abnormalities that will never cause illness of death in the patient’s lifetime. Over diagnosis has become an issue in screenings, not only for breast cancer but also prostate and thyroid cancer.
Researchers nonetheless advise women to continue receiving screens, although they promote focusing screening on higher-risk women in addition to watchful waiting instead of immediate treatment.
The study had limitations, because it compared large groups of people rather than tracking the health of individual women from mammogram on. Other studies have found a 20% reduction in breast cancer deaths as a result of mammography.