Importance of Tumor Cells in Axillary Node Sinus Margins ('Clandestine' Metastases) Discovered by Serial Sectioning in Operable Breast Carcinoma

The prognostic implications of small emboli of carcinoma cells in the sinus margins of axillary lymph nodes ('clandestine' metastases) discovered by serial node sectioning at 2 mm intervals was analysed. All patients, previously untreated, were admitted between 1967 and 1978 and underwent mastectomy and axillary node dissection. Our study examined the risk of distant metastases of 1153 patients with from 0 to 3 involved axillary lymph nodes. A Cox multivariate analysis was performed, taking into account the classical prognostic factors (menopausal status, histoprognostic grade, and anatomic tumor size), and for nodal status including the notion of clandestine (CM) or parenchymal metastases (PM). Compared to patients without axillary metastases, patients with one node involved with CM had a relative risk of distant metastases of 1.7, identical to the risk for patients with one node with PM; and patients with one node containing PM and a second CM, had a relative risk of 2.2. Serial node sectioning discovers nodal metastases that would otherwise not be detected. These CM have important clinical implications and should be taken into account when considering adjuvant manipulations.