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Keywords:

  • breast cancer;
  • molecular subtype;
  • local recurrence;
  • radiotherapy;
  • triple negative;
  • molecular phenotype;
  • breast conservation surgery;
  • radioresistance

Abstract

BACKGROUND:

To assess the potential mechanisms that may underlie increased local failure in triple negative (TN) breast cancers, an analysis was performed of the risk of residual carcinoma after lumpectomy with correlation to pathologic factors, including molecular phenotype.

METHODS:

A review of pathologic specimens was performed for women with invasive breast cancer treated with lumpectomy followed by reexcision. Data were collected on age; tumor size, grade, and nodal stage; estrogen receptor, progesterone receptor, and human endothelial growth factor receptor 2 (Her2); extensive intraductal component; lymphovascular invasion; margins; and reexcision findings. Univariate and multivariate logistic regression analyses were performed to evaluate for associations between pathologic features of the lumpectomy specimen and reexcision findings. Molecular phenotypes were defined by conventionally used immunohistochemical pattern.

RESULTS:

Data were collected on 369 patients with breast cancer. The median age was 57 years, median tumor size was 1.5 cm, 36% had positive margins, 32% had positive lymph nodes, 73.5% had the luminal A subtype, 9.5% had the luminal B subtype, 4.5% were Her2-enriched, and 12.5% were TN. Overall, 32% of patients had invasive cancer in their reexcision specimens, and 51% of those with the TN subtype had residual invasive disease on reexcision compared with 30% to 31% for other subtypes. On univariate analysis, age, tumor size, margin status, lymphovascular invasion, nodal status, and TN subtype were associated with elevated risk of residual invasive cancer. On multivariate analysis using a forward stepwise model, TN subtype maintained significance, with an odds ratio of 3.28 (P = .002).

CONCLUSION:

TN subtype has a statistically significant association with an increased risk of residual tumor. This suggests the putative increase in the risk of local failure in TN patients may be related to increased residual tumor burden. Cancer 2012. � 2012 American Cancer Society.