Pulmonary adenocarcinoma: classification and molecular biology

Pulmonary adenocarcinoma is increasing in incidence. Current classification systems based purely on morphological features are of little clinical relevance. Recent descriptions of genetic abnormalities, particularly in K-ras, p53, and c-erb-B2, may form the basis of a new taxonomy having direct prognostic relevance. Study of these molecular lesions has also helped to define a new pathway of tumourigenesis in the lung parenchyma, through alveolar atypical hyperplasia (AAH) to clinical adenocarcinoma.