As a consequence of population-based screening and the increased use of surveillance mammography, ductal carcinoma in situ (DCIS) now accounts for 20% of newly diagnosed breast cancers; lobular carcinoma in situ (LCIS) is not even considered cancer, and is merely a ‘high risk lesion’.
Lobular Carcinoma In Situ (LCIS)
Now also referred to as LIN – lobular intraepithelial neoplasia, is a risk factor for subsequent invasive carcinoma in either breast, with published relative risks of 8-10 times ‘average’. So, not exactly ‘breast cancer’. Treatment is merely that of high risk patients, so, complete excision, clear margins and radiation are not indicated.
Ductal Carcinoma In Situ (DCIS)
The incidence of ductal carcinoma in situ has been steadily increasing with the widespread use of screening mammography, and now accounts for approximately 20-25% of all breast malignancies. Unlike invasive cancers, the size of DCIS does not have any impact on staging, or outcomes. The risk implied by having this diagnosis, is recurrence of disease. Patients with DCIS who recur, will recur with invasive cancer in about 50% of cases. So the goal of treatment is to reduce this risk.