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Hellenic Archives of Pathology, Volume 20, Issues 1-3, 2006
Investigation of somatostatin receptors
in neuroendocrine carcinomas of the breast
Kontogeorgos G., Horeftaki Th., Thodou E., Pateraki M.
Department of Pathology, G. Gennimatas Athens General Hospital, Athens, Greece
Neuroendocrine carcinomas of the breast are rare primary neoplasms positive for neuroendocrine markers. Well-differentiated tumors are similar to neuroendocrine tumor of other sites, whereas, poorly differentiated neuroendocrine carcinomas are morphologically analogous to small cells carcinomas of the lung. Ten breast carcinomas with histological and immunohistochemical neuroendocrine features were studied. They were separated into two categories: Six of them were classified as neuroendocrine carcinomas containing more than 50% cell positive for neuroendocrine markers and the remaining four as NOS carcinomas with neuroendocrine differentiation showing 10-50% neuroendocrine cells. For immunohistochemistry polyclonal antisera specific for each sstr were used. The standard ABC method combined with the tyramide signal amplification technique was applied with polyclonal antibodies specific for each sstr type. To assess the membranous immunoreactivity, a four-scale scoring system according to the one used for the Her-2/neu in breast carcinomas was utilized. All sstr were detected except for sstr1. They demonstrated heterogeneity regarding the distribution, staining intensity and complete membranous staining pattern. The predominant receptors were sst2B and sst5, followed by sst2A, sst3 and sst4. The score of the membranous immunoreactivity was 1+ in 11 sstr, 3+ in 7 sstr and 2+ in 3 sstr immunostains. In the present study we demonstrated sstr expression in neuroendocrine carcinomas of the breast. Immunohistochemistry for sst is an important tool, mainly for the detection for sstr2 and sstr5, which show high affinity to somatostatin analogs. According to our findings, application of targeted therapy with somatostatin analogs may contribute to achieve the maximum therapeutic goal, particularly in neuroendocrine breast carcinomas with score 3+.
Key words: Immunohistochemistry, tumor markers, breast carcinoma, neuroendocrine differentiation, somatostatin receptors.
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