Clinicopathologic significance of ductal carcinoma in situ in breast core needle biopsies with invasive cancer

To assess whether the presence and amount of intraductal component (IC) in diagnostic needle core biopsies (NCB) is predictive of an extensive IC (EIC), the authors evaluated 50 invasive ductal carcinomas diagnosed with NCB, and then excised via lumpectomy, with regard to the extent of IC in both the NCB and subsequent lumpectomy specimen. These parameters were compared with each other and with the lumpectomy margin status. Extent of IC in the NCB was evaluated by dividing the number of ducts that contained IC by the total number of tissue cores. A ratio of more than 0.5 was considered EIC (EIC(C)). IC extent in the lumpectomy was established by estimating the percentage of the tumor corresponding to IC and was considered extensive (EIC(L)) if more than 25% and if there was presence of IC away from the invasive tumor. The mean size of resected tumors was 1.6 ± 0.7 cm. In 29 cases (58%) there was no IC in the NCB (NegIC(C)), 11 cases (22%) exhibited nonextensive IC (NEIC(C)), and 10 cases (20%) demonstrated EIC(C). A total of 7%, 36%, and 70% of the NegIC(C), NEIC(C), and EIC(C) cases respectively had EIC(L) (p < 0.0001). The presence of EIC(L) correlated significantly with close or positive margin status for in situ disease (EIC(L) positive, 12 of 13 [92%] vs EIC(L) negative, 11 of 37 [30%]; p = 0.004). None of the NegIC(C) 27% of NEIC(C), and 40% of EIC(C) had a positive margin for in situ neoplasm in the lumpectomy specimen (p = 0.004), and 24%, 18%, and 50% had positive margins for invasive neoplasm (p = not significant). The authors conclude that EIC(C) predicts EIC(L) and constitutes a risk factor for positive lumpectomy margin status - particularly for in situ tumor. EIC(C) may thus be of clinical value in identifying a subset of patients that requires a wider local excision.