POSITIVE IMMUNOSTAINING WITH MLUC1 OF BONE-MARROW ASPIRATE PREDICTS POOR OUTCOME IN PATIENTS WITH SMALL-CELL LUNG-CANCER

Background. Immunocytochemistry has been proven able to identify tumor cells in bone marrow aspirate (BMA) of patients with SCLC. However, f ew data exist about the clinical significance of the procedure. Patien ts and methods: 108 BMA taken from 60 patients were incubated with the MoAb MLuCl (cluster 6) and stained by the APAAP (alkaline phosphatase -antialkaline phosphatase) method. The serum levels of LDH, TPA, NSE a nd CEA were also studied in relation to bone marrow involvement by mea ns of discriminant analysis. Results. Immunocytochemistry of the aspir ate with MLuCl detected positive cells in 23 patients (38%) (38 of 108 samples) vs, 13% of the conventional biopsies studied without MLuCl ( P < 0.001). With respect to bone marrow positivity, three groups of pa tients were identified: those with no positive cells in the aspirate a nd negative biopsy (group A); those with less than 10 positive cells i n the aspirate and negative biopsy (group El); and those with more tha n 10 positive cells or clumps in the aspirate or positive biopsy (grou p C). Group C patients had Floorer median survivals than those in the other two groups (5.5 vs, 11 months, respectively, P=0.01). Discrimina nt analysis showed that the four serum markers were poor discriminator s cf the degree of bone marrow involvement, with only 55% of grouped c ases being correctly classified. Conclusions. These results show that detection of bone marrow involvement i) can be improved by the use of MLuCl ii) is not predictable by conventional tumor markers, and iii) i s related to poor outcome.