This is from US News and World Report
It is in regards to melanoma, but I have seen where this substance is being studied on other cancers elsewhere
http://www.usnews.com/usnews/health/briefs/cancer/hb050711a.htm"The Asian spice that gives curried rice its bright yellow color could someday provide researchers with a new way to fight skin cancer. Small doses of curcumin, a spice ground from the turmeric root and a common ingredient in curry, not only stopped the growth of melanoma cells in the lab but also caused the cells to self-destruct, say researchers from the University of Texas's M. D. Anderson Cancer Center in Houston.
The researchers tested curcumin on lab-grown melanoma cells to see if the spice could stop the cells from surviving and reproducing. The more curcumin they added to the melanoma, the more cells died. Unlike normal cells, cancer cells grow uncontrollably and do not self-destruct. Increased doses of curcumin also stopped the melanoma cells from reproducing."
More at the link above