NON-SMALL-CELL LUNG-CARCINOMA TUMOR-GROWTH WITHOUT MORPHOLOGICAL EVIDENCE OF NEO-ANGIOGENESIS

Neoplastic growth is usually dependent on blood supply, and it is comm only accepted that this is provided by the formation of new vessels. H owever, tumors may be able to grow without neovascularization if they find a suitable vascular bed available, We have investigated the patte rn of vascularization in a series of 500 primary stage I non-small-cel l lung carcinomas, Immunostaining of endothelial cells has highlighted four distinct patterns of vascularization. Three patterns (which we c alled basal, papillary, and diffuse) have in common the destruction of normal lung and the production of newly formed vessels and stroma, Th e fourth pattern, which we called alveolar or putative nonangiogenic, was observed in 16% (80/500) of the cases and is characterized by lack of parenchymal destruction and absence of both tumor-associated strom a and new vessels, The only vessels present were the ones in the alveo lar septa, and their presence highlighted, through the whole tumor, th e lung alveoli filled up by the neoplastic cells, This observation sug gests that, if an appropriate vascular bed is available, a tumor can e xploit it and grows without inducing neo-angiogenesis. This could have implications for strategies aimed at inhibiting tumor growth by vascu lar targeting or inhibition of angiogenesis.