Assessment of pathologic prognostic factors in breast core needle biopsies

Core needle biopsies (CNB) are being used increasingly as the initial diagnostic procedure in women with breast cancer. Many clinicians are interested in obtaining as much prognostic information as possible from these limited specimens. However, the accuracy of assessing pathologic prognostic factors in core biopsy material has not been studied in detail.

We studied CNB and subsequent excision specimens from 79 women with invasive breast cancer. Slides from CNB and excision specimens were reviewed in a blinded fashion and each was assessed for histologic type, tumor size, histologic grade, lymphatic vessel invasion (LVI), and the presence of an extensive intraductal component (EIC).

Among the 79 cancers, there were 58 invasive ductal carcinomas, six invasive lobular carcinomas, 13 invasive carcinomas with ductal and lobular features and two tubular carcinomas, based on examination of the excision specimens. Histologic type on CNB correlated with that on excision in 64 cases (81%). Although there was a significant correlation between tumor size on CNB and excision specimens (r2 = 0.30, P = 0.01), the pathologic T stage was underestimated on CNB in 79% of cases. Furthermore, T substage was underestimated on CNB in 71% of T1 lesions. There was concordance in histologic grade between CNB and excisions in 75% of cases. Among the 20 discordant cases, the grade was higher in the excision than in the CNB in 13 cases and lower in seven. However, all discrepancies were within one grade. None of the 17 cancers with LVI in the excision specimen showed LVI on the CNB. Among 14 cases with an EIC on the excision specimen, only four (29%) were scored as having an EIC on CNB.

Histologic type can be accurately determined on CNB in most cases. While there was concordance in histologic grade between CNB and excision in the majority of cases, grade was discordant in a substantial minority (25%). The ability to accurately determine tumor size (pathologic T-stage), LVI, and EIC on CNB is severely limited.