Dr. Marilene Wang, a professor of head and neck surgery, senior author of the investigation and a Jonsson Cancer Center researcher, said:
"The inhibition of the cell signaling pathway also correlated with reduced expression of a number of pro-inflammatory cytokines, or signaling molecules, in the saliva that promote cancer growth.
This study shows that curcumin can work in the mouths of patients with head and neck malignancies and reduce activities that promote cancer growth.
And it not only affected the cancer by inhibiting a critical cell signaling pathway, it also affected the saliva itself by reducing pro-inflammatory cytokines within the saliva."
Due to its anti-inflammatory effects, turmeric has been known for a long time to have medicinal properties. A naturally occurring spice, it is used widely in South Asian and Middle Eastern cooking. Prior investigations have revealed that turmeric can suppress the growth of certain cancers. For several years women in India have used this spice as an anti-aging agent rubbed into their skin, to treat menstruation cramps and as a poultice on the skin to help heal wounds.
A 2005 investigation by Wang and her team first revealed that curcumin restrained the growth of head and neck cancer, first in cells and after in mouse models. In the tests on the mice, curcumin was applied in paste form directly onto the tumors. In an investigation in 2010, also done in cells and mouse models, the team discovered that curcumin suppressed head and neck cancer growth by regulating cell cycling, explained Eri Srivatsan, and adjunct professor of surgery, author and a Jonsson Cancer Center investigator who for seven years, together with Wang, has been investigating curcumin and its anti-cancer properties.
The curcumin binds to and prevents an enzyme known as IKK, an inhibitor of kappa β kinase, from activating a transcription factor called nuclear factor kappa β (NFκβ), which promotes cancer growth.
21 patients with head and neck cancers participated in this investigation, all gave samples of their saliva before and after chewing two curcumin tablets totaling 1,000 mg. After one hour, another sample was taken and proteins were extracted and IKKβ kinase activity measured. Thirteen subjects with tooth decay and five healthy subjects were used as controls, Wang said. Eating the curcumin, she continued, put it in contact with not only the cancer but also with the saliva, and the investigation discovered it reduced the level of cancer enhancing cytokines.
Blind samples were sent to an independent lab in Maryland who confirmed the results. Wang explained:
"the pro-inflammatory cytokines in the saliva that help feed the cancer were reduced in the patients that had chewed the curcumin and the cell signaling pathway driving cancer growth was inhibited.
The curcumin had a significant inhibitory effect, blocking two different drivers of head and neck cancer growth.
We believe curcumin could be combined with other treatments such as chemotherapy and radiation to treat head and neck cancer. It also could perhaps be given to patients at high risk for developing head and neck cancers - smokers, those who chew tobacco and people with the HPV virus - as well as to patients with previous oral cancers to fight recurrence."
Participants tolerated the curcumin well and resulted in no toxic effects. However, the largest problem was that their mouths and teeth turned bright yellow.
The investigation states:
"Curcumin inhibited IKKβ kinase activity in the saliva of head and neck cancer patients and this inhibition correlated with reduced expression of a number of cytokines, IKKβ kinase could be a useful biomarker for detecting the effects of curcumin in head and neck cancer."
In order to be successful in fighting cancer, the curcumin must be taken in supplement form. Even though this spice is frequently used in cooking, the amounted needed to produce clinical response is considerably higher. Wang said: "Expecting a positive effect through eating foods spiced with turmeric is not realistic."
To see if inhibitory effects can be increased, Wang and her team's next step will be treating patients with curcumin for longer periods of time. They aim to treat individuals scheduled for surgery for a few weeks before their operation. To look for differences they will analyze the tissue from a biopsy taken prior to that start of curcumin and at the time of surgery.
"There's potential here for the development of curcumin as an adjuvant treatment for cancer. It's not toxic, well tolerated, cheap and easily obtained in any health food store. While this is a promising pilot study, it's important to expand our work to more patients to confirm our findings."
Discovering ways to treat head and neck cancer more effectively is crucial as often patients require disfiguring surgery, often losing parts of their tongue or mouth, as well as experiencing several side effects, such as difficulty swallowing, dry mouth and have the potential for developing another oral cancer in the future.
The investigation was funded by Veterans Affairs Greater Los Angeles Health System, West Los Angeles Surgical Education Research Center, UCLA Academic Senate, the National Institutes of Health and the Veterans Administration.