PARTIAL REGRESSION IN PRIMARY-CARCINOMA OF THE LUNG - DOES IT OCCUR

Aims: To study immunohistochemically a group of 28 primary lung cancer s which demonstrated histological features reminiscent of those charac teristic of regression in malignant melanoma, to determine the phenoty pe of their immune cell infiltrates. Methods and results: Using a stan dard s-ABC immunoperoxidase method then quantification by the Leica Q5 00 MC image analyser, the cellular infiltrate in these tumours, when c ompared to 67 control cases, showed excess CD3+ T-lymphocytes (P<0.007 ), with an increase in CD4:CD8 ratio and increased CD68+ macrophages ( P=0.00001), CD57+ natural killer cells and S100+ Langerhans cells were also increased, but not quite significantly (P = 0.048 and P= 0.072, respectively). Conclusions: This immunophenotype resembles that shown in regressing skin malignancies and suggests a similar process occurri ng in lung cancer. Regressing lung cancers are associated with a bette r prognosis than matched controls (P = 0.034), some showed radiologica l evidence of growth retardation and the group had an excess of the la rge cell undifferentiated histological type.