Detection of small cell lung cancer bone marrow metastases by immunofluorescence

It is well known that small cell lung cancer (SCLC) has a high propensity to metastasize to the bone marrow and that such involvement has a prognostic significance. A more accurate detection of these bone marrow metastases is thus mandatory. In this study, we analysed the results of the detection of these metastases using an indirect immunofluorescence test. For this purpose, 3 anti-SCLC rat monoclonal antibodies (MoAbs) specific for 3 different antigens (LCA1, LCA2, LCA3) have been utilized to examine 59 bone marrow samples from patients at time of diagnosis and 20 samples from chemotherapy treated patients. Eight patients had bone marrow clearly involved by morphological analysis. They all had fluorescent cells recognized at immunodetection with at least 2 MoAbs positive for 7 out of the 8 samples. Fifteen samples, negative by morphological analysis, were proven positive by immunofluorescence. In 12 cases, involvement was detected only by 1 MoAb (6 anti-LCA1, 2 anti-LCA2, 4 anti-LCA3). A correlation was found between the number of samples proven positive by morphological analysis and the number of positive MoAbs for these samples (p less than 0.005). Among the bone marrow samples provided by the 32 limited disease patients, LCA positive cells were detected in 9 (28%) compared to 14 out of the 27 (52%) samples from extensive disease patients (p less than 0.05). We concluded that the indirect immunofluorescence with a panel of MoAbs increases the rate of detection of bone marrow SCLC metastases.