PROLIFERATION IN MALIGNANT MESOTHELIOMA AS DETERMINED BY MITOSIS COUNTS AND IMMUNOREACTIVITY FOR PROLIFERATING CELL NUCLEAR ANTIGEN (PCNA)

In order to assess its discriminating and prognostic value, we studied immunoreactivity for proliferating nuclear cell antigen (PCNA) in hum an malignant mesothelioma (31 cases) and in human non-neoplastic mesot helium (33 cases with reactive mesothelium and 20 cases of normal meso thelium) using the murine monoclonal antibody PC10. We also compared i t with mitosis counts expressed as the mitotic volume index (MV index) . There were differences between malignant mesothelioma, reactive meso thelium, and normal mesothelium for percentage of PCNA immunoreactive cells (mean +/- SD; 27 +/- 9, 9.5 +/- 5.1, and 3.6 +/- 1.6, respective ly) and for their MV index (20.3 +/- 4.5, 9.4 +/- 2.1, and 3.6 +/- 0.6 , respectively). The median actuarial survival was 10 1 months for pat ients with less than 25 per cent PCNA immunoreactive cells, 9 4 months for patients with less than 20 mitoses per mm(2) of tumoural tissue, 5.9 months for patients with more than 25 per cent PCNA immunoreactive cells, and 5.3 months for patients with more than 20 mitoses per mm(2 ) of tumoural tissue. Our results suggest that PCNA immunoreactivity i s useful in discriminating between neoplastic and non-neoplastic mesot helium and that it may have prognostic value in malignant mesothelioma .