Predicting invasion in the excision specimen from breast core needle biopsy specimens with only ductal carcinoma in situ.

OBJECTIVE: Some patients with ductal carcinoma in situ on breast core needle biopsy will have invasion at excision. The aim of this study was to determine if patients at increased risk for invasion could be identified.
METHODS: The results of all breast core needle biopsies with a diagnosis of ductal carcinoma in situ during a 50-month period were reviewed. A variety of histologic features were identified and correlated with the presence of invasion at excision.
RESULTS: Of 3026 cases, 152 (5%) were diagnosed as ductal carcinoma in situ; excisional biopsies were available for 91 (60%) of these 152 cases, and 17 (19%) showed invasive tumor. Neither the radiographic findings, presence of comedonecrosis, comedo histology, lobular extension, size of the largest focus, nor aggregate size was significantly associated with an increased incidence of invasion (all P >.05). However, comedo histology with a cribriform/papillary architecture was significantly associated with an increased risk of invasion (5/7 [72%] cases with invasion, P =.002), as were tumors greater than 4 mm with lobular extension (6/15 [40%], P =.03).
CONCLUSION: Patients with comedo ductal carcinoma in situ with a cribriform/papillary pattern or tumor involving more than 4 mm with lobular extension in breast core needle specimens are at increased risk for invasion at excision.