e12035 Background: Ductal carcinoma in situ (DCIS) is a heterogenous group of breast lesion and demands a broad range of surgical management techniques. Previous studies reported the importance of receptor expression and referred to the risk of recurrence.We classified ductal carcinoma in situ (DCIS) into 4 subtypes using IHC staining (ER, PgR, HER2 and Ki-67) and investigated the frequency and their characteristics. Also we investigated whether this classification is related to the risk of recurrence. Methods: 117 women who underwent operation between 2010 and 2012 were included our study. We defined 4 subtypes as follows; luminal A (LA), ER and/or PgR (HR)(+) HER2(-) Ki-67(low), luminal B (LB), HR(+) HER2(-) Ki-67(high) or HR(+) HER2(+),HER2(H), HR(-) HER2(+), and basal-like(BL), HR(-) HER2(-).We also evaluated the risk of recurrence using Van Nuys Prognostic Index (VNPI), an algorithm based on DCIS size, nuclear grade (NG), necrosis, margin width and patient age. Results: The frequency of subtype was as follows; LA 77 cases (65.8%), LB 18 (15.3%), H 14 (12.0%) and BL 8 (6.8%). LA tended to smaller size (average: 3.2cm, range: 0.2-12), low NG (NG1 was 97.4%). In a contrary, H and BL were larger size (average: 3.7cm (H), 4.5cm (BL)) and high NG (these percentages of NG3 were 64.3% (H) and 50.0% (BL)). All of the BL had necrosis. About half of the LA was VNPI 6 and 7, but many of the other subtypes were more than VNPI 7 (p=0.02). Conclusions: Classification of subtypes using IHC patterns is simple, useful and, moreover, that are related to the risk of recurrence. Though it is important whether the woman is BRCA1/2 mutation carrier, we might be determined a treatment of DCIS by the subtype.
