The implication of background anthracosis in the development and progression of pulmonary adenocarcinoma.

In order to characterize the relationship between background anthracosis and pulmonary adenocarcinogenesis, surgically resected tissues of 66 cases of stage I pulmonary adenocarcinoma, 4 cm or less at their greatest dimension, were examined. These cases were diagnosed based on the classification of small-sized adenocarcinoma of the lung (Noguchi et al., Cancer 75, 1995). Thirteen cases were diagnosed as types A (localized bronchioloalveolar adenocarcinoma, LBAC) and B (LBAC with alveolar collapse), 40 cases as type C (LBAC with a focus of fibroblastic proliferation), 8 as type D (poorly differentiated adenocarcinoma) and 5 as types E (bronchial gland type adenocarcinoma) and F (true papillary adenocarcinoma). The 5-year survival rate of types A and B cases was 100%, while those of type C, type D and types E and F were 52%, 48% and 39%, respectively. Nuclear accumulation of abnormal p53 protein in non-replacement type adenocarcinomas (types D, E and F) was detected more frequently than that in replacement type adenocarcinomas (types A, B and C) (P < 0.05). In each case, black dusty material was extracted from tumorous lesions and non-tumorous regions and blotted onto a nitrocellulose membrane. The anthracotic index (AI) was calculated with a densitometer. AIs of non-tumorous regions in early and replacement type adenocarcinomas (types A and B) were significantly less than in relatively advanced (type C) and poorly differentiated (type D) adenocarcinomas (P < 0.05). These results indicated that adenocarcinoma developing in heavily anthracotic lungs readily progresses to an advanced stage, or that adenocarcinoma with a less favorable prognosis tends to develop in severely anthracotic lungs.