Occult lymph node metastases in patients with ‘node negative’ breast carcinoma treated with conservation surgery and axillary node sample and who subsequently developed axillary recurrence

We examined axillary lymph nodes from 26 patients with node-negative breast cancer managed by axillary node sampling and no further axillary treatment, but who subsequently developed axillary recurrence after a mean follow-up of 7 years to determine the incidence of micrometastatic disease in these patients. Twenty-six matched controls with an identical length of follow-up who were node-negative on an axillary node sample, but have not developed axillary recurrence, also underwent node examination and the incidence of metastases in the two groups were compared. Lymph nodes were sectioned at two additional levels 100 μm apart. Sections at each level were stained with haematoxylin and eosin (H&E) and antibodies to PanCK and MUC1 protein. The original H&E section from each node was reviewed and additional sections from each lymph node were examined by a pathologist who was blinded to outcome. Review of the original H&E sections of the nodes revealed metastases that had been overlooked at the time of diagnosis in two (8%) patients from the recurrence group. A further two (8%) patients from the recurrence group and three (12%) from the control group had axillary nodes which contained micrometastases. Immunocytochemistry was important in identifying all micrometastases.