Clinical applications of immunocytochemistry in the monitoring of the bone marrow in small cell lung cancer (SCLC).

A panel of monoclonal antibodies (MAbs) has been identified which may be useful in detecting SCLC tumour cells and which does not cross-react significantly with normal marrow elements. Compared with conventional techniques this MAb panel markedly increases detection of micrometastases in the bone marrow especially in limited disease and post-chemotherapy in responding patients. There is a close correlation between immunological positivity and the ability to grow SCLC-like cells for variable periods in serum-free culture. In 4 cases SCLC-like cells have been characterized by electron microscopy or by the establishment of SCLC cell lines in continuous culture. The prognostic importance of pre-treatment detection of marrow involvement is unknown. The implications of post-chemotherapy detection of micrometastases are also uncertain but there may be an association with early systemic relapse which may occur regardless of intervention, including high dose intensification with autologous marrow rescue with primary site and CNS prophylactic irradiation.