2010: Breast Biopsy Type is the Most Important Predictor of Lumpectomy Negative Margins

Abstract

Stereotactic core or needle biopsies are increasing being utilized in breast cancer diagnosis. To evaluate the impact of breast biopsy type relative to clinicopathologic factors in obtaining negative lumpectomy margins. Five hundred and thirty five patients who underwent breast conservation surgery and radiation at Stanford University or the Washington-Stanford Radiation Center for Stage I or II breast cancer during the period1971 -1996 were included in this retrospective analysis. Of these, 399 patients had a defined inked margin status after initial excision and pathologic review. One hundred and twenty nine had negative margins (>2mm) at initial excision, and the remainder had close (98) or positive (172) margins. Sixty seven underwent core or needle biopsy prior to excision and 328 underwent excisional biopsy. The remaining 4 pts underwent incisional biopsy and were excluded from the analysis. The following factors were evaluated for correlation with margins at initial excision: age(<>45), T stage, grade (3/1or2), family history(present/absent), histology (lobular/other), estrogen receptor (ER) status (positive/negative), presence of extensive intraductal carcinoma (EIC), presence of lymphovascular invasion (LVI), and biopsy type (excisional/core or needle) using statistical software (SPSS). The relationship of re-excision and final margin status with biopsy type were evaluated. For initial margin status among the entire group, biopsy type (p<.0001), EIC (p = p.002), ER status (p = .02), lobular histology (p = .02) and age (p = .02) were significantly correlated. Among patients who underwent core or needle biopsy, 52% had negative initial margins as compared to 35% for excisional biopsy. Among patients who underwent core or needle biopsy, only lobular histology (p = .04) and LVI (p=.05) were related to margin status. For patients with lobular histology, none (0/4) had negative margins after core or needle biopsy vs. 55% (23/63) for non-lobular histology. With LVI, 31% (4/13) had negative margins as compared to 64%(23/36) in the absence of LVI. For patients who underwent excisional biopsy, EIC (p = .02) and ER status (p = .02) were significantly related to margin status. The rate of re-excision was 34% for patients diagnosed with core or needle biopsy vs. 61% with excisional biopsy (p<.0001). The percentage of patients with negative final margin status was similar with either core/needle or excisional biopsy (79 and 78% respectively). However, more patients had close or negative final margins after core/needle than after excisional biopsy (p=.03), and more patients had positive final margins after excisional biopsy (p = .01) suggesting some variation in re-excision and/or patient selection policies between the two groups. Biopsy type is the most significant clinicopathologic predictor of initial margin status. Pre-excision diagnosis with core or needle biopsy may reduce the deterimental effect of EIC, ER negativity, and younger age on initial margin status and the need for re-excision in these patient groups. Patients with lobular histology or LVI may require improved preoperative imaging and/or planning to increase the rate of negative margins at initial excision after needle or core biopsy. The attainment of negative final margin status appears similar for all biopsy types.