Prognostic and therapeutic impact of sentinel node micrometastasis in patients with invasive breast cancer

Aims and background: Locoregional lymph node status is one of the most important prognostic factors determining the need for adjuvant chemotherapy in patients with breast cancer. Many authors have reported that micrometastases were not detected by routine sectioning of lymph nodes but were identified by multiple sectioning and additional staining. Among lymph node-negative patients 15-20% had an unfavorable outcome at five years from primary surgery. Sentinel lymph node (SLN) biopsy is an accurate technique for identifying axillary metastases because the pathologist utilizes hematoxylin-eosin (H-E) staining together with immunohistochemistry (IH) to examine all lymph node sections. Sentinel node micrometastasis has therefore become an important tumor-related prognostic factor. Methods and study design: From November 1997 to October 2001 we examined in 210 patients the pathological features of primary breast lesions and SLN metastases and we correlated these with the tumor status of non-SLNs in the same axillary basin. We applied IH examination to both SLNs and non-SLNs of patients who were negative for metastasis by standard H-E examination. Results: In this study lymph node staging was based on SLN findings, primary tumor size, and the presence of peritumoral lymphovascular invasion (LVI). We found 18 SLN micrometastases (9%) in 210 patients and one of these (5.5% of patients with SLN micrometastasis) also had one non-SLN metastasis: this patient had LVI and a larger primary tumor than patients with SLN micrometastasis without non-SLN metastasis. We also found 24 SLN macrometastases (11.5%) in 210 patients and 13 of these (54.2% of patients with SLN macrometastases) had one or more non-SLN metastases. Conclusions: According to the results reported in the literature, tumor cells are unlikely to be found in non-SLNs when the primary lesion is small and SLN involvement micrometastatic (5.5% in our experience. 7% in Giuliano's). Our findings suggest that axillary lymph node dissection may not be necessary in patients with SLN micrometastasis from T1 lesions.