Carcinoembryonic antigen as differentiation marker for small cell lung cancer in vitro and its clinical relevance.

Fifteen small cell lung cancer (SCLC) cell lines and 249 histopathological specimens from patients with SCLC were investigated for carcinoembryonic antigen (CEA) expression. Quantitative determinations of CEA in cell line homogenates correlated significantly (p less than 0.001) with L-DOPA decarboxylase (DDC) activities and population doubling times (PDT). Using monoclonal antibodies specific for CEA (BW 431/31) and crossreactive with non-specific crossreacting antigens (NCA) 55 and 95 (BW 250/183 and BW 374/14), the CEA-reactive moiety in SCLC was immunologically identified as CEA. In vivo studies demonstrated CEA by immunohistochemistry in 57% (141/249) of newly diagnosed SCLC. The presence of CEA and the degree of immunostaining did not correlate with clinical parameters.