Expression of 'small cell carcinoma antigens' in primary small cell lung cancer and metastases: an immunohistochemical study

The presence of 'small cell lung cancer antigens' was evaluated in pretreatment biopsies of primary SCLC, liver metastases, and/or bone marrow metastases from 46 patients. The antigen expression was detected immunohistochemically by applying monoclonal antibodies to routinely formalin-fixed and paraffin embedded tissue. The antibodies applied were second workshop codes: 3(CAM 5.2), 45 (MOV15), 54 (NCCST433), 75 (PE35), 81 (HMFG-1), 95 (LCA1/L38) and HMFG-2 123C3, F4 and MOC-21. High expression was observed for WS 3, 45, 75, 81 and HMFG-2, both in the primaries and metastases. A good correlation was observed between the presence of antigens in primary biopsies and metastases, but there was a general tendency toward a lower proportion of positive tumour cells in the metastases compared to the primaries. For WS 45, 54, 75 and 95 the difference between primaries and bone marrow was statistically significant, and this was also true for WS 45 and 81 in the liver. The clinical relevance is discussed.