Ductal Carcinoma In Situ: The Impact of Screening on Clinical Presentation and Pathologic Features

Abstract: It has been suggested that mammographic screening may produce an overdiagnosis bias leading to unnecessary treatment for inconsequential ductal-carcinomain-situ lesions. To assess the malignant potential of ductal carcinoma in situ, we compared pathologic features and presentation of ductal carcinoma in situ in patients treated before (1969–1985) and after (1986–1990) the intensified use of screening at our institution. We reviewed 204 cases of ductal carcinoma in situ in patients treated between 1969 and 1990. Histologic slides were available for 145 patients. Pathologic features evaluated included histologic subtype and nuclear grade. When the prescreening era was compared with the postscreening era, the incidence of palpable mass decreased from 54% to 12%, ductal discharge decreased from 14% to 3%, Paget's disease decreased from 10% to 3%, and mammographically detected lesions increased from 19% to 80%. The incidence of comedo subtype increased from 14% to 36% (p = 0.0195). Seven percent of palpable masses and 38% of mammographically detected ductal-carcinoma-in-situ lesions were of the comedo subtype, which presented almost exclusively as a mammographic abnormality (p < 0.0015). Grade 1 lesions decreased from 38% to 28%, and grade 3 lesions increased from 24% to 33%. Palpable masses tended to be lower grades and mammographically detected lesions tended to be higher grades. The malignant potential of mammographically detected lesions as determined by grade and histologic subtype is greater than that of symptomatic ductal carcinoma in situ. Mode of presentation does not appear to be a useful prognostic factor. Mammographically detected ductal carcinoma in situ is not an inconsequential finding and should not be treated as such.