Prognostic significance of an interface pattern of central fibrosis and tumor cells in peripheral adenocarcinoma of the lung.

Fifty-nine surgically resected pulmonary adenocarcinomas were histologically classified into four types (A, B, C, and D) according to the pattern of invasion, ie, the extent of invasive tumor cell growth in the interface zone between alveoli replaced by cancer cells and the central region of fibrosis (so-called "scar"). In pattern A cancer cells proliferate along the alveolar walls without forming a frankly invasive lesion. In pattern B invasive lesions occupy less than 30% and in pattern C more than 30% of the fibrosing area. Pattern D refers to invasion of the bronchial lumen by cancer cells. The 59 tumors included 14 of pattern A, 12 of pattern B, 16 of pattern C, and 17 of pattern D. The 5-year survival rate for patients with pattern A tumors was 100%, and the rates for patients with pattern B, C, and D tumors were 64.2%, 30.0%, and 11.8%, respectively. Each difference between pairs of survival curves was statistically significant (P < .05). We found a correlation between the pattern of invasion and other prognostic factors. However, even in the cases evaluated as favorable by other prognostic factors (stage I, tumor less than 35 mm in diameter, negative for lymph node metastases, well-differentiated histology, negative for subpleural invasion, negative for vascular invasion) the survival curves became steeper going from pattern A to patterns B, C, and D. We conclude that the pattern of invasion is correlated with the prognosis of surgically treated patients. Our study may provide new histological criteria for the prognostic evaluation of pulmonary adenocarcinoma.