Histopathology of lung cancer.

Lung cancer is a complex problem because there are a number of different histological cell types. Those commonly grouped as bronchogenic carcinoma (epidermoid carcinoma, adenocarcinoma, large cell undifferentiated carcinoma, small cell carcinoma, and adenosquamous carcinoma) account for more than 90% of the new cases and the deaths each year. The natural history of bronchogenic carcinoma suggests that many years pass while the cancer evolves from a pre-cancerous change in the bronchial mucosa, to undetectable microscopic cancer, to preclinical asymptomatic cancer and finally into a full symptomatic cancer, the phase of most lung malignancies in the tissue at diagnosis. Therefore, students of the aetiology of this disease must consider what has happened to patients 5-20 years before lung cancer is diagnosed.