SCREENING INTERVAL BREAST CANCERS - MAMMOGRAPHIC FEATURES AND PROGNOSTIC FACTORS

PURPOSE: To review the mammographic features of screening interval bre ast cancers and to compare the tumor size, histologic grade, and lymph node involvement with those in screening-detected and unscreened symp tomatic cancers. MATERIALS AND METHODS: Screening mammography was perf ormed in 72,773 women aged 50-64 years. Ninety interval cancers were i dentified in 89 women. The mammographic and histopathologic features o f these cancers were analyzed. RESULTS: At review of the screening mam mograms, interval cancers were classified into four groups: 51 true-po sitive, 20 false-negative, seven mammographically occult, and 12 uncla ssified. The most common missed abnormality in the false-negative case s was architectural distortion. Interval cancers were larger, of highe r 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. CONCLUSION: Prognosi s in interval cancers is similar to that in symptomatic, unscreened tu mors and statistically significantly worse than that in screening-dete cted cancers.