Third, it is well established that neoplasms frequently produce hormones, cytokines, growth factors and other bioactive substances, although these neoplasms are rarely associated with clinical humoral syndromes. Increasing knowledge of the biological implications of bioactive substances produced by neoplastic cells indicates that these substances can act directly on neoplastic cells or tissues that surround the neoplastic cells, which in turn function to support neoplastic cell growth.
In this context, the concepts of ectopic humoral syndromes and ectopic production of bioactive substances by neoplasms are now attracting remarkable attention from clinical and scientific researchers in oncology as well as in endocrinology.
