Figure 3. Pathobiologic Events Associated with Ductal Carcinoma in Situ.
The molecular, cellular, and pathological processes that occur in the transformation from healthy tissue to preinvasive lesions, such as ductal carcinoma in situ, to breast cancer are shown. The majority of the changes that give rise to cancer, including the accumulation of genetic changes, oncogene expression, and the loss of normal cell-cycle regulation, appear to have occurred by the time ductal carcinoma in situ is present. Most of the clinical features of a subsequent invasive breast cancer are already determined at this stage, although additional events, including tissue invasion and changes in the surrounding stroma, characterize the invasive tumor .