To determine the histological or immunohistochemical characteristics of ductal carcinomas in situ (DCIS) that could influence margin status at first surgery and at final surgery.
We retrospectively studied the 485 breast carcinomas diagnosed in 2003, 2004 and 2005 at the Doce de Octubre Hospital (Madrid), of which 54 (11.1%) were DCIS and 280 (57.7%) were invasive ductal carcinomas (IDC).
Only 10%of DCIS were palpable. DCIS represented 25%of all carcinomas diagnosed by mammographic wire-guided biopsy. We found positive margins on first breast-conserving surgery in 50%of DCIS and in 34%of IDC. Consequently, a second or even a third intervention (for persistently involved margins) was more frequent in DCIS than in IDC. In DCIS higher histological grades were associated with more frequent margin involvement and a higher rate of re-excision with positive margins and mastectomy. The mastectomy rate in DCIS (43%) was higher than that in IDC diagnosed by mammographic wire-guided biopsy (27%), and was similar to that in IDC overall (41%).
Mammographic screening programs have improved the detection of DCIS, but clear margins are sometimes difficult to achieve in this entity, leading to the paradox that women with palpable IDC are able to undergo breast-conserving surgery without compromising prognosis, whereas a mammographically detected DCIS requires mastectomy.