Abstract
BackgroundThe effect of breast cancer subtype on margin status after lumpectomy remains unclear. This study aims to determine whether approximated breast cancer subtype is associated with positive margins after lumpectomy, which could be used to determine if there is an increased risk of developing local recurrence (LR) following breast-conserving surgery.MethodsWe studied 1,032 consecutive patients with invasive cancer who received lumpectomies and cavity margin (CM) assessments from January 2003 to November 2012. The following data were collected: patient age, cT stage, pT stage, grade, status of CM, lymph node status, menopausal status, ER, PR, HER-2, and Ki67, as well as the presence of extensive intraductal component (EIC) and lymphovascular invasion (LVI). A χ2 test was used to compare categorical baseline characteristics. Univariate and multivariate logistic regression analyses were performed to evaluate associations between pathologic features of CM status. Kaplan-Meier actuarial cumulative rates of LR (ipsilateral in-breast) were calculated.ResultsA total of 7,884 pieces of marginal tissue were collected from 1,032 patients, and 209 patients had positive CMs. Of the patients tested, 52.3% had luminal A subtype, 14.9% were luminal B, 12.8% were luminal-HER-2, 8.1% were HER-2 enriched, and 11.8% were triple negative. Univariate analysis showed that EIC (P <0.001), LVI (P = 0.026), pN stage (N1 vs. N0: P = 0.018; N3 vs. N0: P <0.001), and luminal B (P = 0.001) and HER-2 (P <0.001) subtypes were associated with positive CMs. Multivariable analysis indicated that only EIC (P <0.001), pN stage (P = 0.003), and HER-2 subtype (P <0.001) were significantly correlated with positive CMs. On multivariable analysis, HER-2 subtype was an independent prognostic factor in LR (P = 0.031).ConclusionsThe HER-2 subtype was the predictive factor most associated with positive CMs and an independent prognostic factor for LR. This result suggests that the increased risk of LR in HER-2 breast cancer is due to an increased microscopic invasive tumor burden, which is indicated by margin status after lumpectomy.Electronic supplementary materialThe online version of this article (doi:10.1186/1477-7819-12-289) contains supplementary material, which is available to authorized users.
Highlights
The effect of breast cancer subtype on margin status after lumpectomy remains unclear
Patient selection We retrospectively reviewed the clinical and histopathologic data of 1,032 consecutive women ranging from 22 to 89 years at the time of diagnosis with clinical stage I or II invasive breast cancer (BC) deemed suitable for breast-conserving surgery (BCS) treated with lumpectomy and cavity margin (CM) excision between January 2003 and November 2012 in our center
We found that compared to the other BC subtypes, the TN subtype was most commonly observed at an age of 36 to 50 years, and the human epidermal growth factor receptor 2 (HER-2) subtype was commonly observed at an age of >50 years and frequently exhibited extensive intraductal component (EIC), larger tumor size, and positive margins
Summary
The effect of breast cancer subtype on margin status after lumpectomy remains unclear. This study aims to determine whether approximated breast cancer subtype is associated with positive margins after lumpectomy, which could be used to determine if there is an increased risk of developing local recurrence (LR) following breast-conserving surgery. DNA microarray profiles have been used to classify breast tumors into distinct biologic subtypes [1,2] This testing may not often be feasible in a clinical setting, and these subtypes can be approximated by the expression of immunohistochemically-defined biological markers, such as the estrogen receptor (ER), the progesterone receptor (PR), and the human epidermal growth factor receptor 2 (HER-2), to classify tumors as luminal A (ER+ or PR+ and HER-2−), luminal B (ER+ or PR+ and HER-2+), HER2+ (ER− and PR− and HER-2+), or triple-negative (TN) (ER− and PR− and HER-2−) subtypes [3]. Negative margins should be achieved during BCS as recommended by the National Comprehensive Cancer Network guidelines
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