Zebrafish as model system for cancer development

It is well know that patients with densely innervated tumors exhibit more metastasis and poorer survival than those with less innervated tumors. In general, innervated tumors are more aggressive and recruitment of nerve fibres to cancer tissue is associated with higher proliferative indices and a greater risk of recurrence and metastasis. Today, the concept that blood and lymphatic vessels are the main players in cancer progression and dissimilation is changing and more and more focus is being placed on the role of tumor innervation, referred to as neoneurogenesis. Clearly, an improved understanding of reciprocal interactions between cancer and nerve cells will provide new insights of considerable value for therapeutic intervention against cancer progression. An extremely important consideration in this connection is that factors released by the nervous system as a consequence of psychological and social pressures may alter the efficiency drugs used to treat cancer. Zebrafish provide a useful model for human tumors, because it is easy to induce malignant tumors in these animals by transplantation, as well as to monitor subsequent progression in vivo by imaging and test the effects of drugs.