PB.40. What happens to the ductal carcinoma in situ in HER2-positive cancers treated with neoadjuvant chemotherapy and trastuzumab?

There are few data regarding the effect of neoadjuvant chemotherapy (NACT) and trastuzumab on any ductal carcinoma in situ (DCIS) associated with the HER2-positive invasive carcinoma. HER2-positive breast cancers are more likely to achieve a pathological complete response (defined as absence of invasive tumour in the final excision specimen allowing for the presence of DCIS). We review our data to see what happens to HER2-positive DCIS associated with HER2-positive invasive cancer treated with NACT.