Since the first report in 1984 showing that the inhibition of the histamine-synthesizing enzyme, HDC which catalyzes the biosynthesis of histamine from histidine, resulted in antitumoral effects on experimental tumors in rodents 46, a large body of experimental evidence has supported the critical role of HDC and histamine in tumor development and progression 5,6,12–17. This evidence concerns the gene HDC and neoplasm.