Clinical implications of occult metastases and isolated tumor cells in sentinel and non-sentinel lymph nodes in early breast cancer patients: serial step section analysis with long-term follow-up.

Background: This study was designed to clarify retrospectively the clinical significance of occult metastases in both sentinel lymph nodes (SLNs) and non-SLNs in patients with early breast cancer.

Methods: A total of 109 (80.1%) of 136 women with breast cancer who had consecutively undergone SLN biopsy (176 lymph nodes) were intraoperatively diagnosed as being free of SLN involvement. SLNs were routinely examined by hematoxylin-eosin (HE) staining of one to four frozen sections per node. Sixty-four (58.7%) of these patients also underwent backup axillary dissection. For the 109 patients, all formalin-fixed, paraffin-embedded tissues of SLNs and non-SLNs were entirely cut into 5-μm-thick sections. All serial step sections at 85-μm intervals were stained with HE and immunohistochemistry with pancytokeratin.

Results: Occult metastases in SLNs and non-SLNs were detected in 25 (23%) and 10 (16%) patients, respectively. The presence of occult SLN metastasis was marginally correlated with T-factor (P=0.06), and predictive factors for occult non-SLN metastases were tumor nuclear grade (P=0.039). With a median follow-up of 86 months, disease-free survival (P=0.3) or overall survival (P=0.8) did not differ between the patients with and without occult SLN metastases, regardless of backup axillary lymph node dissection.

Conclusions: SLN or non-SLN occult metastases detected by serial step sections at 85-μm intervals did not have significant prognostic implications.