Ductal carcinoma in situ (DCIS)

Does the detection and proper treatment of ductal carcinoma in situ (DCIS) contribute to mortality reduction? In other words, does the detection of DCIS prevent the development of metastatic invasive cancer and thereby death? Although we assume that DCIS is the obligate pre-stage of most invasive breast carcinomas, it is unlikely that all DCISs have the potential to progress to an invasive process within the lifetime of the patient. This assumption is based on histologic review studies indicating that certain types of DCIS (the well differentiated types) have a limited risk of progressing to an invasive cancer. Recently, Böcker reported close genetic similarity of well, intermediately and poorly differentiated DCISs and distinct morphologic types of invasive breast cancers. Further, Lampejo et al. reported a significant difference in disease-free survival and overall survival for patients with invasive tumours with different types of DCIS components. Patients with poorly differentiated DCIS components had a poor prognosis and those with well differentiated DCIS components had a very good one. We may conclude that all fully developed DCISs have the potential to progress to an invasive cancer. The time needed for this process, however, is different for the poorly and well differentiated subtypes. For the majority of the poorly differentiated DCISs this may take less than 5 years, while for the well differentiated type it probably takes more than 10–15 years. Poorly differentiated DCIS is the precursor of high-grade, and well differentiated DCIS of low-grade invasive cancer. Therefore, the detection of the poorly and intermediately differentiated DCIS is more important in terms of effect on mortality than the detection of the well differentiated subtype.