Predictors of axillary lymph node metastases in patients with T1 breast cancer. A multivariate analysis.

Background: In T1 tumors, the reported incidence of lymph node metastases ranges from 21% to 35%. The authors analyzed the pathology parameters of T1 tumors for their association with the likelihood of axillary lymph node metastases.

Methods: Two hundred sixty-three patients with T1 unilateral invasive breast cancer were studied. All underwent axillary dissection, and the pathologic status of the nodes was known. The parameters of the primary tumor evaluated included size, histologic subtype, nuclear grade, DNA ploidy, S-phase fraction (SPF), hormone receptor status, lymphatic/vascular invasion (LVI), and host reaction.

Results: Seventy-two (27%) patients had nodes that were positive for metastasis. Univariate analysis showed that lymph node metastases were associated with tumors larger than 1 cm (P = 0.001), moderate or poorly differentiated nuclear grade (P = 0.005), high SPF (P = 0.041), presence of LVI (P < 0.001) and patients younger than 60 years (P = 0.01). However, independent predictors of lymph node metastasis in the multivariate logistic regression analyses were tumor size and LVI. Twenty-five patients had tumors larger than 1.0 cm and presence of LVI; of these, 17 (68%) had lymph node metastases. Of the 79 patients who had neither of these features, only 7 (9%) had lymph node metastases.

Conclusions: The authors conclude that characteristics of the primary tumor can help assess the risk for axillary lymph node metastases. Selected patients who are assessed to be at minimal risk might be spared routine axillary dissection or radiation therapy to the axilla.