Abstract P6-06-39: Chest wall invasion is a more significant prognostic factor than nodal spread, triple-negative or Her2 receptor status in stage III breast cancer: A large, single institution retrospective analysis

Abstract

Abstract Background There is a significant variation in response to systemic treatment in stage III breast cancer that is not explained by hormone/Her2 receptor status alone. Identification of additional prognostic factors is needed to further stratify patients for additional treatment. According to the National Cancer Data Base, patients with stage IIIB breast cancer, characterized by having direct chest wall involvement regardless of lymph node spread, have a worse prognosis than patients with stage IIIC breast cancer, generally with significant lymph node involvement (41% vs. 49% 5-year overall survival). We hypothesized that chest wall invasion is an independent prognostic factor and may be more significant than regional nodal spread, triple-negative or Her2 -receptor status, or ethnicity. Methods Our retrospective study included 135 patients with stage IIIB or IIIC breast cancer seen at a large county hospital in Dallas, TX between 2008 and 2013. Patients were stratified into two groups based on whether they had chest wall invasion (T4) or not. Cases of inflammatory breast cancer (T4d) were excluded. Kaplan-Meier survival curves, the Log-Rank test, univariate and multivariate methods were used for statistical analysis. We evaluated the effects of chest wall involvement, ethnicity, and hormone receptor/Her2 status on overall survival. Results In patients with stage III breast cancer, those with chest wall invasion (T4) have a significantly decreased 5-year overall survival (OS) compared to patients with significant regional nodal spread (N3) (62% vs. 81%, p = 0.022, HR 2.3, 95% CI: 1.1-4.9). Univariate analysis of hormone receptor, Her2 status, African-American or Hispanic ethnicity, the presence of chest wall involvement, and significant regional lymph node involvement (N3 disease or not) showed that ER receptor status and the presence of chest wall involvement were the only significant prognostic factors (p = 0.006 and p = 0.022, respectively). Notably, the combination of ER-negativity and the presence of chest wall invasion predicts for worse prognosis than either alone (p = 0.0011, HR 1.6, 95% CI: 1.2-2.2). Conclusion and Discussion Chest wall invasion was an independent predictor for decreased overall survival in stage III breast cancer. This could explain in part why patients with stage IIIB breast cancer have worse overall survival than patients with stage IIIC. There may be an intrinsic biological difference between breast cancer cells that directly invade surrounding chest wall and those that have nodal spread as the main route of metastasis. An inflammatory component in those with chest wall invasion may allow these tumors to be more aggressive and additional research is needed to target potential genes for therapy. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-39.