Influence of mammographic parenchymal pattern in screening-detected and interval invasive breast cancers on pathologic features, mammographic features, and patient survival.

OBJECTIVE: The aim of our study was to assess the effect of mammographic parenchymal pattern on patient survival, mammographic features, and pathologic features of breast cancer in a screened population.
MATERIALS AND METHODS: We classified the parenchymal pattern (according to BI-RADS) of 759 screened women who presented with a screening-detected (n = 455) or interval (n = 304) invasive breast cancer. Pathologic details (tumor size, histologic grade, lymph node stage, vascular invasion, and histologic type) and mammographic appearances were recorded. Breast cancer-specific survival was ascertained, with a median follow-up of 9.0 years.
RESULTS: An excess of interval cancers was seen in women with dense breasts (p < 0.0001). Screening-detected (but not interval) tumors were significantly smaller in fatty breasts (p = 0.014). Tumor grade, lymph node stage, vascular invasion, and histologic type did not vary significantly with mammographic parenchymal pattern in screening-detected or interval cancers. Screening-detected cancers in fatty breasts were more likely to appear as indistinct (p = 0.003) or spiculated (p = 0.002) masses in contrast to cancers in dense breasts, which more commonly appeared as architectural distortions (p < 0.0001). No significant breast cancer-specific survival difference was seen by mammographic parenchymal pattern for screening-detected cancers (p = 0.75), interval cancers (p = 0.82), or both groups combined (p = 0.12).
CONCLUSION: The prognosis of screened women presenting with breast cancer is unrelated to dense mammographic parenchymal pattern despite an excess of interval cancers and larger screening-detected tumors in this group. These data support the mammographic screening of women with dense parenchymal patterns.