Screening interval breast cancers: mammographic features and prognosis factors.

Abstract

To review the mammographic features of screening interval breast cancers and to compare the tumor size, histologic grade, and lymph node involvement with those in screening-detected and unscreened symptomatic cancers. Screening mammography was performed in 72,773 women aged 50-64 years. Ninety interval cancers were identified in 89 women. The mammographic and histopathologic features of these cancers were analyzed. At review of the screening mammograms, interval cancers were classified into four groups: 51 true-positive, 20 false-negative, seven mammographically occult, and 12 unclassified. The most common missed abnormality in the false-negative cases was architectural distortion. Interval cancers were larger, of higher grade, and more likely to have lymph node involvement than screening-detected tumors and were of similar size, histologic grade, and stage of lymph node involvement as symptomatic tumors. Prognosis in interval cancers is similar to that in symptomatic, unscreened tumors and statistically significantly worse than that in screening-detected cancers.