In-situ and microinvasive squamous cell carcinoma of the lung

A study of 20 patients with carcinoma in situ or microinvasive squamous cell carcinoma of the lung indicates that such tumours originate in the surface epithelium of the bronchus, most commonly in the segmental bronchi, and may spread along the mucosa of both the bronchial lining and the submucosal glands. Stromal invasion may occur from either site and involve a considerable length of bronchus without significantly compromising the bronchial lumen or altering the radiographic appearance of the lung. The majority of patients will be cured by surgical resection, but about 20 per cent will die of causes related to the tumour, including the development of a second lung cancer. Presumably at least some bronchogenic squamous cell carcinomas presenting clinically as large and/or advanced cancers have evolved through phases similar to those described here and could have been detected at an earlier stage in their evolution by periodic sputum cytological examinations.