Background: Bronchioloalveolar carcinoma (BAC) of the lung is a subtype of adenocarcinoma for which the incidence is actually rising, but the histologic definition of BAC has been recently changed by the revised World Health Organization (WHO) classification in 1999. The clinical features of patients with BAC diagnosed according to the recently revised WHO classification have not yet been clarified. In this retrospective study, we investigated the pattern of recurrence and survival outcome for patients with resected BAC by pathology review, compared with those in patients who had adenocarcinoma other than BAC.
Methods: From 1985 through 2002, 108 patients underwent surgical resection for pulmonary adenocarcinoma 3 cm or less in diameter at the University of Yamanashi, Japan. All of the resected specimens of these 108 patients were pathologically reviewed again to confirm the diagnosis as BAC or adenocarcinoma other than BAC. The tumor was defined as BAC when the adenocarcinoma lesion had a pure bronchioloalveolar growth pattern and no evidence of stromal, vascular, or pleural invasion according to the WHO classification (third edition).
Results: Twenty-five patients (23%) had a diagnosis of BAC, and 83 (77%) had a diagnosis of other adenocarcinoma. There was a female predominance among both patients with BAC and those with other adenocarcinoma. Lymph node involvement was seen for 30 lesions (36%) of adenocarcinoma other than BAC, but not for any BAC lesions. The median duration of follow-up after surgery was 5.1 years. There was no recurrence in the postoperative course in patients with BAC for a 5-year disease-free survival rate of 100%, whereas the 5-year disease-free survival rate for other adenocarcinoma was 63.5%.
Conclusions: The patients with resected BAC, which is defined as a noninvasive adenocarcinoma by the revised WHO classification, had an excellent prognosis. However, these results may depend on a strictly accurate pathology diagnosis as BAC. Limited resection might be curative in patients with focal BAC based on evidence of pathologic noninvasive features.