July 7, 2015
U.S. Breast Cancer Screening Data Lead to Questions About the Value of Mammography
Thomas L. Schwenk, MD reviewing Harding C et al. JAMA Intern Med 2015 Jul 6. Elmore JG and Etzioni R. JAMA Intern Med 2015 Jul 6.
Higher uptake of mammography is associated with more cancer diagnoses but not with lower cancer-specific mortality.Despite some trials showing lower breast cancer–related mortality associated with screening mammography, controversy about its benefit persists, because most trials were conducted decades ago, and screening practices and treatments have changed. Researchers used data on 16 million women (age, ≥40) from 547 U.S. counties to identify the percentage who had undergone mammography in 1999 or 2000 (range, 39%–78% across counties). In these same counties, about 53,000 women were diagnosed with breast cancer in 2000 and were followed for at least 10 years.
Significant correlation was noted between the proportion of county residents screened by mammography and the rate of breast cancer diagnoses, with a 10–percentage-point increase in screening associated with a 16% increase in breast cancer diagnoses. Mammography use was associated significantly with the diagnosis rate of both small (≤2 cm) and large (>2 cm) cancers. No association was found between rate of mammography and 10-year breast cancer–associated mortality.
Comment
An ideal screening program should lead to detection of more small cancers and fewer large cancers over time and should be associated with lower cancer-specific mortality. In this study, mammography was associated with a higher rate of small-cancer diagnoses, but also with a higher rate of large-cancer diagnoses and no fewer cancer-specific deaths. Although several explanations for these epidemiological findings are possible, the most compelling is that widespread mammography leads to overdiagnosis of clinically unimportant cancers that have no effect on mortality. According to editorialists, these findings should encourage clinicians who are counseling patients about mammography to
be more explicit about overdiagnosis risk.Editor Disclosures at Time of Publication
Disclosures for Thomas L. Schwenk, MD at time of publication Editorial boards UpToDate
Citation(s):
Harding C et al.
Breast cancer screening, incidence, and mortality across US counties. JAMA Intern Med 2015 Jul 6; [e-pub]. (Δεν είναι ορατοί οι σύνδεσμοι (links).
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Elmore JG and Etzioni R.
Effect of screening mammography on cancer incidence and mortality. JAMA Intern Med 2015 Jul 6; [e-pub]. (Δεν είναι ορατοί οι σύνδεσμοι (links).
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- See more at: Δεν είναι ορατοί οι σύνδεσμοι (links).
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