Another abstract on melatonin and cancer but the real bombshell for me is this
Omega six = linoleic acid found in high quanitities in corn safflower sunflower walnut soy Evening primrose many of which are to be found in processed foods margarines etc. IF this topic is new to you see "Omega three omega six the importance to breast cancer" and the "breast cancer diet" on the articles of interest section.
ABSTRACT
In further experiments, Blask's team determined that melatonin blocks cancer cells' metabolism of linoleic acid, a polyunsaturated fat that's abundant in food. The same team had previously shown that 13-hydroxyoctadecadienoic acid, the product of linoleic acid metabolism, spurs cancer cells to divide.
Link
http://www.sciencenews.org/articles/20060107/bob9.asp