Diarrhea
There’s a type of cancer that synthesizes a hormone called vasoactive intestinal peptide. This is a neurocrine substance, which means it regulates the function of neurons in various parts of the body. It relaxes the muscles of the arteries causing vasodilation, and this would drag extra water to the intestines. Excessive secretion of this substance would cause a severe case of diarrhea that impairs the normal absorption and usually leads to dehydration.