Lymphatic invasion, tumor size, and age are independent predictors of axillary lymph node metastases in women with T1 breast cancers

OBJECTIVE: To identify characteristics of the primary tumor highly associated with lymph node metastases. SUMMARY BACKGROUND DATA: Recent enthusiasm for limiting axillary lymph node dissection (ALND) in women with breast cancer may increase the likelihood that nodal metastases will be missed. Identification of characteristics of primary tumors predictive of lymph node metastases may prompt a more extensive surgical and pathologic search for metastases in patients with negative sentinel lymph nodes or limited ALND. METHODS: The authors studied 850 consecutive patients who underwent ALND for T1 breast cancer. Age, tumor size, histopathologic diagnosis, tumor differentiation, presence of lymphatic invasion, and estrogen and progesterone receptor results were studied prospectively. Stepwise logistic regression was used to identify variables independently associated with axillary lymph node metastases. RESULTS: Lymphatic invasion, tumor size, and age were independently associated with lymph node metastases. Fifty-one percent of the 181 patients with lymphatic invasion had axillary lymph node metastases, compared with 19% of the 669 patients without lymphatic invasion. Thirty-five percent of the 470 patients with tumors >1 cm had nodal involvement compared with 13% of the 380 patients with smaller cancers. Thirty-seven percent of the 63 women younger than age 40 had lymph node involvement compared with 25% of the 787 women older than age 40. Significant correlations were noted between lymphatic invasion and patient age and between lymphatic invasion and tumor size. The proportion of tumors with lymphatic invasion decreased progressively with increasing age and increased with increasing tumor size. CONCLUSIONS: Axillary lymph node metastases are most significantly related to lymphatic invasion in the primary tumor, followed, in order of significance, by tumor size and patient age. Axillary nodal metastases should be suspected in the presence of lymphatic invasion of large tumors in young patients.