COMPARATIVE ASPECTS OF NEOPLASTIC INVASION OF THE BRAIN

This review of the invasion of the human brain by tumors is based upon a comparative approach. The taxonomic distribution of a structure of the CNS to be considered a brain is present in the following taxonomic groups: Mollusca (Cephalopoda, Pulmonata) Sipunculida, Echiurida, Ann elida, Arthropoda and Vertebrata (fishes, amphibians, reptiles, birds and mammals). The comparative approach (inter-, and intraspecies speci fic) provides a more informative, indicative, understanding of invasio n of the human brain; especially in view of the morphological and func tional heterogeneity of structures playing a role in the neoplastic in vasion to and from the brain. It can be distinguished among primary in vasiveness (as cancer in situ) and local recurrence on the one hand an d remote spreading, such as metastasis, on the other. A review of the recent literature arranged according to tumor types is provided and co mparative conclusions elucidated, especially to underline the tumor sp ecificity of the invasion of brain tumors, especially the second or in tra-species specific approach is therapeutically important. This is se t forth against a background of epidemiology and species specificity. Due to the lack of bony skull capsule an extensive knowledge of the br ain of cephalopod molluscs with its functional and morphological simil arity to the human eye, and also that of the pulmonate Helix pomatia, the vineyard snail, could well serve as excellent oncologic models. So me conclusions can be drawn dealing with the theoretical possibility o f first appearance of the different and heterogeneous components of th e complicated structure known as brain including its supporting access ory organs during phylogeny.