New approach to assessing lung tumours in man.

One hundred and four surgically resected lung tumours were labelled in either cryostat or freeze dried sections with a monoclonal antibody (Ki67), which reacts with a nuclear antigen expressed by proliferating cells. The tumours were categorised semiquantitatively into four proliferative grades, a classification that can be performed rapidly and reproducibly by the pathologist. In keeping with previous cell kinetic studies all small cell carcinomas had high proliferation rates, whereas the carcinoid tumours were in the lowest grade. In contrast, the adenocarcinomas (27 cases) and squamous cell carcinomas (63 cases) varied widely in their proliferative state, in keeping with their heterogeneous, morphological, and clinical behaviour. Immunocytochemical labelling of lung tumour biopsy specimens with antibody Ki67 is a simple technique within the scope of routine surgical pathology laboratories, which might enable these tumours to be classified according to their proliferative status and treatment to be selected accordingly.