Specificity of mammography and US in the evaluation of a palpable abnormality: retrospective review.

PURPOSE: To determine the number of patients who received a diagnosis of breast cancer after having an area of clinical concern at presentation and combined negative mammographic and ultrasonographic (US) findings.

MATERIALS AND METHODS: During a 4-year period, 829 patients with a palpable abnormality at presentation and combined negative mammographic and US findings were identified. The number of women who went on to receive a diagnosis of breast cancer was determined retrospectively. The authors searched the breast imaging database and the pathology database, sent a contact letter to the referring physicians, and linked their data to the State Cancer Registry. They also analyzed the breast parenchymal density among all patients who had more than 2 years of follow-up.

RESULTS: Of the 829 women, 374 had follow-up information. Two-hundred thirty-three patients had negative imaging findings with more than 2 years of follow-up. The other 141 women were presumed to be cancer free, as they were not identified by the State Cancer Registry. Six (2.6%) of the 233 women had a diagnosis of breast cancer in the area of the palpable abnormality. The six cancers were diagnosed among the 156 women who had radiographically dense breast tissue (Breast Imaging Reporting and Data System category 3 or 4). Among the 77 women with predominantly fatty tissues, no cancers were diagnosed.

CONCLUSION: A negative mammographic and US finding of a palpable abnormality does not exclude breast cancer, but the likelihood of breast cancer is low, approximately 2.6%-2.7%. It may be higher if the breast tissues are dense and lower if they are predominantly fatty.