Analysis of prior mammography with negative result in women with interval breast cancer.

PURPOSE: The purpose of our study was to review mammographic findings which were previously negative in women with interval breast cancer and to analyze the histopathological features of the interval breast cancer.

MATERIALS AND

METHODS

A total of 5521 women underwent surgery for breast cancer between January 2009 and December 2011. Among them, 240 women who had undergone available, previous mammography studies reported as normal or benign (mean interval between examinations, 9.7 months) were included in our study. We reviewed the previous mammographic features and categorized as true interval breast cancer, minimal sign, and missed interval breast cancer. Histopathological findings were also reviewed.

RESULTS

Of the 240 diagnosed cancers, 78 (32.5 %) were classified as true interval breast cancer, 78 (32.5 %) as minimal sign, and 84 (35 %) as missed interval breast cancer. True interval breast cancer occurred in a younger age and showed dense breast compared with missed breast cancer. The breast density of 169 patients (70.4 %) was dense. In the minimal sign group, the most common finding was normal appearing tissue (61/78), followed by benign-appearing calcification (17/78). There were no significant differences in the histopathological findings in each of the three groups and tended to have smaller tumor size, negative nodal status, a lower AJCC stage, and frequent luminal A subtype.

CONCLUSION

The majority of interval breast cancers was not detectable in patients with dense breast or showed subtle mammographic findings on previous mammography. Although the majority of breast cancers showed a low grade in the histopathological findings, a better understanding of the mammographic findings will influence the sensitivity of mammography.