Telomerase activation in adenocarcinoma-bronchioloalveolar carcinoma

Abstract

At present, human bronchioloalveolar carcinoma (BAC) is a disease with an evolving definition. The clinical concept of BAC needs to be re-evaluated with careful attention to the 2004 World Health Organization (WHO) criteria 1 due to major clinical implications. Series published in the literature before 2000, i.e. before the WHO definition of BAC, had not discerned a specific survival advantage and clinical behaviour for BAC as compared with other nonsmall cell lung cancers (NSCLC). Instead, existing data indicate that patients with solitary small peripheral BAC, characterised by pure lepidic growth pattern with no evidence of stromal vascular or pleural invasion, represent only 2–6% of NSCLC diseases and have 100% 5-yr survival. This survival advantage may be extended to the micro-invasive BAC according to Japanese observations 2. Indeed, most lung adenocarcinomas, including those with a predominant BAC component, are invasive and consist of a mixture of BAC (noninvasive) with invasive histological patterns such as acinar, papillary or solid growth. The high predominance of these mixed subtype adenocarcinoma justified the moving of this category to the top of the list of subtypes in the 2004 WHO classification 1. There are several pathological and radiological growth presentations of mixed subtype adenocarcinoma with a BAC component, including solitary peripheral nodules, multiple nodules and lobar consolidation, which can all be unilateral or bilateral. When BAC or mixed adenocarcinoma present with a diffuse parenchymal infiltration pattern (multicentric nodules and lobar consolidation), their macroscopic and radiological presentations are that of pneumonic-type adenocarcinoma. Although previously called pseudopneumonic BAC, most of these tumours are adenocarcinoma mixed subtype with the whole spectrum of the BAC acinar, papillary and solid pattern 3. There are clear differences in the pathological, radiological and clinical implications of solitary small peripheral lung adenocarcinoma and these pseudopneumonic multicentric and diffuse consolidation patterns. The …