Predictors of Residual Tumor in Breast-Conserving Therapy.

Background: Breast-conserving therapy is considered to be the standard treatment for early breast tumors (T1-T2). In up to 82 % of breast-conserving surgery, tumor cells were still found to be present at or near the cut edge of the surgical specimen after surgery. Thus, it is of clinical need to identify tumors at high probability for reexcision in the preoperative setting.

Methods: A total of 686 patients with invasive or in situ breast cancers and primary breast-conserving surgery were included. In 169 cases (24.6 %), breast-conserving therapy was either incomplete or the presence of residual tumor could not be assessed. By univariate analysis, the following parameters were associated with increased probability for reexcision: carcinoma in situ component next to the invasive tumor (p < 0.001), lower age (p = 0.025), premenopausal status (p = 0.033), tumor size (p < 0.001), multifocality (p < 0.001), involved lymph nodes (p = 0.006) and lymphovascular invasion (p < 0.001), differentiation (p = 0.002), and overexpression of the Her2/neu receptor (p = 0.004). The variables with the strongest impact on the reexcision probability in multivariate analyses were tumor size and histology (both p < 0.001), followed by multifocality (p = 0.002) and an accompanying carcinoma in situ (p = 0.004). Lymphovascular invasion (p = 0.016) and age (p = 0.047) also were significantly associated with increased reexcision probability in multivariate analyses. A nomogram for predicting residual tumor in breast-conserving therapy was developed.

Conclusions: The clinical and pathological parameters associated with increased reexcision rates will help to assess an optimized surgical margin, to decrease reexcision rates, and therefore to improve patient care and the quality of life for patients.