Objective: The objective of this study was to determine if restrictive risk-based mammographic screening could miss breast cancers that population-based screening could detect.
Materials and methods: Through a retrospective search of records at a single institution, we identified 552 screen-detected breast cancers in 533 patients. All in situ and invasive breast cancers detected at screening between January 1, 2011, and December 31, 2014, were included. Medical records were reviewed for history, pathology, cancer size, nodal status, breast density, and mammographic findings. Mammograms were interpreted by one of 14 breast imaging radiologists with 3-30 years of experience, all of whom were certified according to the Mammography Quality Standards Act. Patient ages ranged from 36 to 88 years (mean, 61 years). The breast cancer risks evaluated were family history of breast cancer and dense breast tissue. Positive family history was defined as a first-degree relative with breast cancer. Dense breast parenchyma was either heterogeneously or extremely dense.
Results: Group 1 consisted of the 76.7% (409/533) of patients who had no personal history of breast cancer. Of these patients, 75.6% (309/409) had no family history of breast cancer, and 56% (229/409) had nondense breasts. Group 2 consisted of the 16.7% (89/533) of patients who were 40-49 years old. Of these patients, 79.8% (71/89) had no family history of breast cancer, and 30.3% (27/89) had nondense breasts. Ductal carcinoma in situ made up 34.6% (191/552) of the cancers; 65.4% (361/552) were invasive. The median size of the invasive cancers was 11 mm. Of the screen-detected breast cancers, 63.8% (352/552) were minimal cancers.
Conclusion: Many screen-detected breast cancers occurred in women without dense tissue or a family history of breast cancer. Exclusive use of restrictive risk-based screening could result in delayed cancer detection for many women.
Keywords: breast cancer; mammography; risk; screening.