Significance of intramammary lymph nodes in the staging of breast cancer: correlation with tumor characteristics and outcome.

Intramammary lymph nodes (intraMLNs) have received little attention as potential prognostic indicators for patients with breast carcinoma. Patients with stage I breast carcinoma and positive intraMLN metastases have been reported to have a poorer prognosis compared to patients with similar stage and negative intraMLN metastases. However, the presence of intraMLN metastases does not appear to influence the survival of patients with stage II breast carcinoma. In the current retrospective analysis, we assessed the clinical significance of intraMLNs and evaluated their role in predicting outcome in patients with breast carcinoma. Between 1995 and 2005, 116 intraMLN specimens were identified. In all, 59 patients (50.8%) were found in association with benign breast conditions and the remaining 57 (49.2%) with primary breast carcinoma. Primary tumor characteristics and axillary lymph node (AxLN) status were recorded. Outcome data were documented. Statistical analysis was performed to detect correlation between intraMLN and tumor characteristics as well as outcome. IntraMLN metastases were found in 26% of all in-situ and invasive cancer cases (15/57), and 32% (15/47) of invasive cancer cases only. Most patients (80%) who had intraMLN metastases also had axillary metastases; however, an isolated intraMLN metastasis was documented in one patient (7%). Univariate analysis revealed that predictors of intraMLN metastases include: tumor size (p = 0.04), tumor grade (p = 0.04), tumor stage (p < 0.001), and AxLN status (p < 0.001). Furthermore patients with intraMLN positive for metastases have a poorer 4-year overall (40% versus 88%; p < 0.001) and disease-free survival (37% versus 83%; p < 0.001) than patients with negative intraMLN. On multivariate analysis, intraMLN metastasis is not an independent predictor of outcome (disease-free survival: p = 0.350; and overall survival p = 0.138). IntraMLN metastasis is a poor prognostic marker but not an independent predictor of poor outcome in patients with breast carcinoma.