Intramammary lymph node metastases are an independent predictor of poor outcome in patients with breast carcinoma

BACKGROUND Breast carcinoma with intramammary lymph node (intraMLN) metastases is considered to be Stage II disease, even in the absence of axillary lymph node involvement. Nonetheless, little is known regarding the clinical significance of intraMLN metastases. The goals of the current retrospective analysis were to elucidate the clinical relevance of intraMLN metastases and to assess the relation between such metastases and outcome in patients with breast carcinoma. METHODS One hundred ninety‐six intraMLN specimens obtained between 1983 and 2003 were identified in the pathology database at The University of Texas M. D. Anderson Cancer Center (Houston, TX); 130 of these specimens were obtained in association with a primary breast malignancy. Data on the clinical and pathologic features of these specimens were collected and evaluated on univariate and multivariate analysis for potential correlations with 5‐year rates of disease‐free survival (DFS), disease‐specific survival (DSS), and overall survival (OS). The median follow‐up duration was 36 months (range, 12–180 months). RESULTS The median age of the 130 patients in the current study was 53 years (range, 27–84 years). Twenty‐four patients (18%) had intraMLNs that were identified preoperatively by either mammographic or sonographic methods; in the remaining 106 cases, intraMLNs were detected on pathologic examination of surgical breast specimens. IntraMLN metastases were found in 28% of all cases (n = 36). Most patients who had intraMLN metastases (81%) also had axillary metastases; however, isolated intraMLN metastases were documented in 6 patients (5%). Univariate analysis revealed that patients with intraMLN metastases (compared with all other patients) had poorer 5‐year rates of DFS (54% vs. 89%; P = 0.001), DSS (66% vs. 90%; P = 0.001), and OS (64% vs. 88%; P = 0.004). Furthermore, multivariate analysis indicated that intraMLN involvement was an independent predictor of reduced DFS (hazard ratio, 2.33; P = 0.03), DSS (hazard ratio, 5.32; P = 0.002), and OS (hazard ratio, 3.22; P = 0.006). CONCLUSIONS The current retrospective analysis demonstrated that the presence of intraMLN metastases is an independent predictor of poor outcome in patients with breast carcinoma. Identification of an intraMLN on preoperative imaging should prompt further histopathologic assessment. Identification of malignant intraMLNs by lymphatic mapping may help to identify high‐risk patients for whom further evaluation of the a