I posted this in advanced prostate cancer - but I think it is valuable enough to bring here also:
This is well worth reading. It's rather dense and while non-conclusive on the mechanisms at work - the results are what's interesting. A common "supplement" Melatonin has been found to have multiple cancer benefits in preventing or slowing the spread of metastatic cancer, and in making treatment-resistant cancers once again sensitive to treatment.
Thoughts and comments are welcome!