Screening mammography for second breast cancers in women with history of early-stage breast cancer: factors and causes associated with non-detection.

BACKGROUND: The aim of our study was to identify the factors and causes associated with non-detection for second breast cancers on screening mammography in women with a personal history of early-stage breast cancer.

METHODS: Between January 2000 and December 2008, 7976 women with early-stage breast cancer underwent breast surgery in our institution. The inclusion criteria of our study were patients who had: (a) subsequent in-breast recurrence, (b) surveillance mammography within 1 year before recurrence. Retrospective analysis of mammography was performed. Non-detection was defined as second breast cancers that were not visible on screening mammography. Imaging features, demographics, primary breast cancer (PBC) characteristics, and clinical features were evaluated to determine its association with non-detection. Univariate and multivariate logistic regression analyses were also performed to identify the factors related to non-detection.

RESULTS: We identified 188 patients that met the criteria. Among them, 39% of patients showed non-detection (n = 74). Of the 74 patients with non-detection, 53 (72%) were classified as having no detectable mammographic abnormality (i.e., true negative) due to overlapping dense breast tissue (n = 32), obscured by postoperative scar (n = 12) or difficult anatomic location / poor positioning (n = 9). The remaining 21 patients were categorized as having subtle findings (n = 11) or missed cancer (n = 10). Non-detection for second breast cancers were significantly associated with mammographic breast density (p = 0.001, OR = 2.959) and detectability of PBC on mammography (p = 0.011, OR = 3.013).

CONCLUSION: Non-detection of second breast cancer in women with a personal history of early-stage breast cancer were associated with mammographic dense breast and lower detectability of PBC on mammography.