We've spoken here before about the premature extrapolation of in vitro data on curcumin to the misleading human use of the spice-derivative for a whole host of cancers. Unfortunately, curcumin is not absorbed into the bloodstream at concentrations necessary for anticancer effects, even when combined with a black pepper-derived compound called piperine (sold under the brand name, Bioperine). In fact, piperine/Bioperene may present a risk of drug interactions and potentially increase the side effects of some types of chemotherapy if taken unwittingly along with certain drugs.

However, a cancer prevention specialist at the University of California at Irvine is investigating curcumin systematically in a precancerous setting where it has some potential of having benefit. As the featured clinical trial in yesterday's NCI Cancer Bulletin, "Phase II Chemoprevention Study of Curcumin in Current Smokers with Aberrant Crypt Foci" (UCIRVINE-UCI04-2-01), proposes to investigate whether 30 days of curcumin administration reduces the incidence of precursor lesions to colon cancer. (See the protocol summary at http://cancer.gov/clinicaltrials/UCIRVINE-UCI04-2-01.).

This trial is clever in that it takes advantage of the fact that curcumin is poorly absorbed from the gastrointestinal tract. Moreover, it is not aimed at treating colon cancer that has already occurred but rather cellular lesions that are beliefed to precede the development of colon cancer.

From the interview with UC-Irvine's Dr Frank Meyskens:

Microscopic lesions in the lining of the colon called aberrant crypt foci (ACF) are thought to be precursors of colon polyps and, ultimately, malignant tumors. ACF lesions typically display biomarkers that may indicate precancerous development. In this trial, researchers are exploring the ability of a substance called curcumin to affect these biomarkers and possibly stop the progression to cancer...

Doctors are interested in determining whether curcumin supplements taken for 30 days can help reduce the levels of precancerous biomarkers in the ACF of smokers who have eight or more lesions. Smoking is a known risk factor for colon cancer, and studies suggest that as many as 80 percent of smokers have ACF lesions.

"Though it has been used for centuries in traditional medicine, we're very early in the clinical development of curcumin as a chemopreventive agent," Dr. Meyskens said. "This trial is a proof-of-principle study to see if curcumin really can affect the relevant biomarkers in humans. If it does, we can then design a larger cancer prevention trial based on demonstrated biological response rather than on results from epidemiological studies."

Note that what this trial is not doing is testing curcumin against already advanced colon cancer. This will be an interesting trial to follow, again, especially since it seems to take advantage of the fact that curcumin is poorly absorbed from the intestinal tract.

Other investigators and enrollment sites are; Dr. Richard Banya, University of Illinois at Chicago; Dr. D. Kim Turgeon, University of Michigan.

My earlier posts on curcumin:
Curcumin for cancer: part one
Curcumin for cancer: part two