Curcumin - Part III: Cancer Studies
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This is the third of a series of articles on the beneficial actions of curcumin in a vast number of diseases including diabetes, heart disease, neurodegenerative disease such as Alzheimer’s, cancer, arthritis, skin and oral diseases. (1,2) Curcumin is a safe, natural substance derived from the spice tumeric. There is a vast body of evidence of the benefits of this phytonutrient with over 4000 scientific studies confirming its various health promoting actions. There is also a substantial and growing body of evidence that curcumin may not only help prevent various types of cancer, but may also play a supporting role in their treatment.
Curcumin: Cancer Prevention
For those who have been diagnosed with cancer, it can seem as though the cancer developed practically overnight. In reality, the process of cancer development usually starts years, or even decades prior to diagnosis and involves multiple molecular pathways after initial carcinogen exposure.(3)
Chemopreventive agents exert their protective effects by blocking any one of these pathways in cancer development. Impressively, curcumin blocks not just one, but several mechanisms recognized in the development and progression of many cancers. (3-16) In fact, having tested over 1000 substances since 1987 the National Cancer Institute in the United States found that only 40 showed promise in preventing or treating cancer. Of these curcumin was singled out as one of the stars of this select group with multiple streams of evidence indicating that it may have unparalleled cancer-fighting abilities. (3)
The preventive role of curcumin has been well established with hundreds of in vitro lab studies and animal studies. Human studies establishing a preventive role are more difficult to design and execute but a number have been carried out.
Evidence of Cancer Prevention - Lab Studies
In vitro lab studies have demonstrated that curcumin can inhibit the growth of various cancer cells from different organs including breast, ovary, prostate, colon, liver, pancreas, head and neck, brain, blood and skin cancers. (17)
In animal studies the rate of cancer development resulting from exposure to known potent carcinogens has been assessed for various types of cancer. These studies revealed that curcumin either completely prevented or reduced the number of breast, oral, stomach, liver, colon, rectum and other tumors that developed compared with control animal subjects. Furthermore, curcumin was able to suppress growth of implanted cancers of the pancreas, bladder, prostate and other tumours. (17) Both orally administered and topical curcumin was able to arrest the growth of squamous cell carcinoma implanted in the skin in mice. (18)
Of great significance, other studies indicate that curcumin may also reduce the rate of metastasis. (17) Curcumin reduced the lung metastasis of melanoma cells by eighty percent and increased survival rates of the affected animals by 150%. In fact curcumin proved to be the most effective of more than a dozen agents that were similarly tested. (19) In another study, 68% of mice who were implanted with breast cancer cells showed no or few metastases, compared to 17% of control animals. (19)
Evidence of Cancer Prevention - Human Studies
Clearly this type of approach is not feasible in human studies but evidence of the protective effect of curcumin has been gleaned from observing its effect on the level of cancer biomarkers and on slowly developing and pre-cancerous conditions.
As an example, in studies on familial adenomatous polyposis, where there is a strong genetic predisposition to colon cancer, curcumin significantly reduced the number of pre-cancerous polyps detected in the bowel. The number of abnormal polyps was reduced by forty percent after curcumin was administered for thirty days and when combined with quercetin, another powerful phytonutrient, the number was reduced by sixty percent within six months! (20,21) Similar findings were made in studies of multiple myeloma which is a potentially fatal blood based cancer: a well designed randomised, double-blind placebo-controlled cross-over study indicated that curcumin may have the potential to slow the disease process in precursor conditions leading to multiple myeloma. (22)
Cancer Treatment and Support
Despite its multi-targeted protective effects, curcumin has not been established as a standalone agent for the treatment of cancer, but as a supportive role in tandem with standard cancer therapies. Amazingly, there is evidence that curcumin performs a dual role in that it sensitizes cancer cells to the action of chemotherapy and radiotherapy, while protecting normal cells form their toxic effects. This has multiple potential benefits including greater efficacy in eradicating even resistant cancer cells, inhibiting metastasis and allowing reduced dosing of these toxic agents. These can all add up to reduced side effects and increased well being for cancer patients.
In fact, curcumin has been shown to sensitize a host of different chemotherapy agents and radiotherapy. These results were observed in breast, colon, pancreas, gastric, liver, blood, lung, prostate, bladder, cervix, ovary, head and neck, and brain cancers and in multiple myeloma, leukemia, and lymphoma based on lab studies of cancer cell lines and studies in rodents. (23) As an example of this synergism, curcumin combined with the chemotherapy agent capecetebine for colorectal cancer was found to reduce ascites (distension of abdomen due to collection of large volumes of fluid), tumour volume and other important indices of cancer activity compared to capecetebine alone. Very importantly, the combination was highly effective at suppressing distant metastases (spread) to the liver and other organs. (24)
Naturally, these findings, although very promising, cannot be automatically extrapolated to use in humans. Despite impressive results from animal studies, there is only early data regarding the improved quality of life and response in humans. The lack of long term data regarding combination of chemotherapy with curcumin has led some experts to recommend its use before or after chemotherapy courses, rather than during chemotherapy at this point. It is vitally important to consult with your oncologist to determine if and how curcumin can be used in combination with the therapy you have been prescribed.
There is pretty good evidence in regard to combination curcumin with radiotherapy in breast cancer based on the results of a small but well designed clinical trial. (25) This randomized, double-blind, placebo-controlled clinical trial confirmed that use of curcumin led to a significant reduction in both the rate and severity of radiation dermatitis in 30 breast cancer patients. Seeing that radiation dermatitis occurs in 95% of these cases, with 10% having severe reactions, this was an important finding.
Challenges and Exciting New Developments
In spite of the impressive findings outlined above a challenge that been repeatedly highlighted in clinical studies is the poor bioavailability (absorption), transformation to less active metabolites (conjugated form) and rapid excretion of curcumin. As a result, study participants had to ingest large quantities of curcumin and some of the dramatic responses obtained in animal, and particularly in vitro studies, have not yet been realized in clinical studies.
Secondly, although curcumin is the most active constituent of tumeric, some of the other components of tumeric such as polysaccharides, are active in their own right. As a result some of the activity documented in studies using tumeric extract may be lost with pure curcumin formulations. On the other hand, simply ingesting whole tumeric powder only results in minuscule amounts of either curcumin or the polysaccharides.
To meet the first challenge, two greatly superior curcumin formulations have recently become available - Longvida™ and most recently, CurQfen™. They not only offer increased bioavailability and proven bio-accessibility, but are the only formulations which have been shown to produce clinically relevant levels of the far more active “free” curcumin. (26,27) They are also able to pass the blood brain barrier, which is of great significance for potentially targeting brain tumours and other neurological diseases such as Alzheimer’s. (28,29)
LongvidaTM was the first giant leap forward but CurQfen™ shows even greater absorption and distribution within the cells. A large number of studies on CurQfen™ are currently underway, including one human study published in 2018 (30) which showed a forty percent reduction in enzymes associated with alcoholic liver damage over a two month period. In view of the fact that there has been a staggering increase in the incidence of liver cancer worldwide - up 75% from 1990 to 2015 - and one of the predisposing factors factors for liver cancer is chronic liver damage, this is a significant finding.
Our Curcumin Ultra™ formulated by Advanced Orthomolecular Research, incorporates CurQfen and goes one step further to includes tumeric polysaccharides in the form of Turmacin™. Turmacin™ used alone has also shown promising results in osteoarthritis patients.
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