Background: Neoadjuvant chemotherapy facilitates breast conservation in stage II breast cancer patients, whose primary tumors are assumed to be invasive because they are palpable. However, chemotherapy may not be indicated in the minority of patients whose clinically T2 tumors are completely or predominantly in situ. Almost all previous studies of core needle biopsy in breast cancer have been concerned with nonpalpable, mammographically detected tumors, and none have evaluated its ability to quantitatively determine the amounts of in situ and invasive disease.
Methods: From September, 1992 to December, 1997, core needle biopsy was performed on all patients presenting to the Kings County Hospital Breast Clinic with palpable breast masses. Carcinoma was present in both core needle biopsy samples and surgical specimens subsequently obtained from 95 of 99 patients. Each specimen was evaluated for tumor type, histologic grade, and the amounts of in situ and invasive carcinoma it contained, and the results from surgical and core needle biopsy specimens from the same patients were then compared.
Results: The surgical specimens of 14 patients had completely or predominantly in situ disease. Completely or predominantly invasive disease was present in 67 specimens, and the remaining 14 had significant amounts of both. The high level of agreement between the amounts of in situ and invasive disease in core needle biopsy and surgical specimens is indicated by Pearson and intraclass correlation coefficients of 0.91 (P < .001 and < .00001, respectively). Tumor type was correctly predicted by core needle biopsy in each case. Variables among these patients, including primary tumor size, interval between biopsy and surgery, or administration of neoadjuvant systemic therapy, did not alter agreement between core needle biopsy and surgical specimens.
Conclusions: Core needle biopsy can identify palpable breast tumors that are predominantly or completely in situ, and, thus, avoid unnecessary neoadjuvant chemotherapy. It also can demonstrate that a tumor is predominantly invasive, but cannot rule out small invasive foci. For that purpose, complete surgical excision of the tumor is required.