DNA analysis of in situ ductal carcinoma of the breast via flow cytometry.

Flow cytometric (FCM) DNA analysis of 41 clinical cases of ductal carcinoma in situ (DCIS) of the breast was performed on fine-needle aspirates of unfixed, frozen tissue. Based on analysis of a single tissue sample, abnormal DNA content was found in 35 (85%) of the cases, and 15 (37%) disclosed heterogeneity. If five or more samples were analyzed, then heterogeneity was found in eight of ten cases. No conclusive correlation could be found between DNA index (DI) and histopathology. Our results on DCIS demonstrate a very high concordance with invasive breast cancer with respect to the frequency of DNA nondiploid cases, distribution of DI, occurrence of multiple clones, and S-phase fraction. This indicates that major genetic alterations and DNA heterogeneity are early events in carcinogenesis that are already established at the preinvasive stage.