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Case-control study of factors associated with failure to detect breast cancer by mammography.

BACKGROUND
Although mammography is widely used to detect breast cancer, it is recognized that not all cancers can be seen on mammographic images.


PURPOSE
Our purpose was to examine factors associated with failure to detect breast cancer by mammography.


METHODS
A case-control study was carried out in which subjects in whom histologically verified breast cancer was not detected by mammography (false negatives) were contrasted with subjects in whom breast cancer had been detected by mammography (true positives). Mammograms from individuals with histologically confirmed breast cancer were classified independently by two radiologists who were unaware of the clinical or other characteristics of the subjects. Histologic slides of all tumors were reviewed by one pathologist.


RESULTS
Three variables were found to be independently and significantly associated with failure to detect breast cancer by mammography. Breast cancer was less likely to be detected by mammography in the presence of extensive parenchymal densities (odds ratio [OR] = 9; 95% confidence interval [CI] = 1.8-44.3), a tumor of lobular histology (OR = 7; 95% CI = 2.2-22.1), and tumors of small size (OR = 0.10; 95% CI = 0.0-0.9).


CONCLUSION
Our results indicate that biologic factors are associated with failure to detect some breast cancers by mammography and indicate directions for future research in breast imaging.