Purpose: To evaluate the frequency and prognostic importance of neuroendocrine differentiation (NED) in Japanese breast cancer patients.
Methods: We used standard immunohistochemical techniques to examine 50 patients who underwent resection of breast cancer between 1988 and 1993 at the Department of Surgery II, Nagoya University Hospital, for NED, defined as positive reactivity for four markers: neuron-specific enolase (NSE), synaptophysin, CD57, and chromogranin A (CGA). Neuroendocrine differentiation was defined by the presence of at least one marker including CGA, CD57, and synaptophysin, or at least two markers when one was positive for NSE.
Results: Neuroendocrine differentiation was found in 13 (26%) of the 50 patients examined. There were no significant differences in the distribution of patients with positive or negative NED in terms of age, menopausal status, tumor size, lymph node metastasis, histological grade, ER, PgR, and HER2. We calculated the cumulative survival rates of patient groups according to NED status, and found no significant difference in overall or disease-free survival between patients with and those without NED.
Conclusion: Neuroendocrine differentiation was identified in a subset (26%) of Japanese breast cancer patients, but this appeared to have no relationship with established prognostic factors or patient outcome.