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Home > Living Well > Health Library > Curcumin (Curcuma, Turmeric) and Cancer (PDQ®): Integrative, alternative, and complementary therapies - Health Professional Information [NCI]
This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http://cancer.gov or call 1-800-4-CANCER.
This cancer information summary provides an overview of the use of curcumin as a treatment for people with cancer.
This summary contains the following key information:
Curcumin is a member of the diarylheptanoid class of natural products (curcuminoids) derived from the rhizome of Curcuma longa L., an East Indian plant, commonly called turmeric. The other major curcuminoids present in turmeric are demethoxycurcumin, bisdemethoxycurcumin, and cyclocurcumin; together, they are termed the curcuminoid complex. The turmeric plant and preparations derived from it have a long history of therapeutic application in traditional Asian medicine. The crude and often dried plant material is widely consumed as a food additive, as part of curry spices, which typically contain numerous other ingredients. Turmeric and its preparations also have a long history of use as herbal medicines and dietary supplements, primarily to treat various inflammatory disorders.
Significant confusion exists in the scientific biomedical literature, as well as the popular literature, about the meaning of curcumin. Consequently, one group has developed a classification scheme that is described below.
Several companies distribute curcumin as a dietary supplement. In the United States, dietary supplements are regulated as foods, not drugs. Therefore, premarket evaluation and approval by the U.S. Food and Drug Administration (FDA) are not required unless specific disease prevention or treatment claims are made. The FDA can remove dietary supplements from the market that are deemed unsafe. Because dietary supplements are not formally reviewed for manufacturing consistency, ingredients may vary considerably from lot to lot. In addition, there is no guarantee that ingredients claimed on product labels are present at all or are present in the specified amounts. The FDA has not approved the use of curcumin as a treatment for cancer or any other medical condition.
Categories of Curcumin-type Products
The materials that have received the moniker curcumin may be divided into five categories:
It is important to note that materials often referred to as curcumin are not identical to the pure, single-chemical entity. Because of the deficiency in the adequate chemical characterization of the immense diversity of crude turmeric (T), extracts (CE), enriched materials (CTE, CEM), and even materials considered pure, augmented by the fact that the materials often share the same name (curcumin), the usefulness of the biological data acquired from the plethora of these preparations is questionable. Furthermore, attributing biological activity of a complex mixture solely to the major component, however prominent, is problematic.
This summary refers to all turmeric-derived intervention materials by using the collective term, curcumin-containing products. Tables at the end of each section specify the exact intervention material used in each cited study.
Extensive research over the past two decades suggests that curcuminoids belonging to the diferuloylmethane class of natural products, the major constituents in turmeric (Curcuma longa), interfere with multiple cell signaling pathways, which provides support for the potential role of curcumin in modulating carcinogenesis. These pathways include the following:[1,2,3,4,5,6,7,8,9,10,11,12]
While these reports can possibly provide support for the potential role of curcumin-containing products in modulating carcinogenesis, definitive conclusions cannot be made, especially in light of the widespread confusion and/or misconception regarding the chemical nature of curcumin-containing products outlined above.
Because of the abundance of in vitro and preclinical studies in the past two decades, there has been a significant increase in the number of clinical trials investigating the therapeutic potential of curcumin-containing products. These clinical trials have used varying formulations and doses of curcuminoids for the prevention and treatment of cancer and to ameliorate symptoms of cancer treatment. This summary will focus on the bioavailability, safety, and effectiveness of curcumin-containing products reported in clinical trials that targeted individuals at high risk of cancer and cancer patients for the prevention and treatment of cancer and ameliorating the symptoms of cancer treatment.
Bioavailability of Curcumin-Containing Products (Phase I Clinical Trials)
At least six phase I clinical trials of curcumin -containing products have investigated the pharmacokinetics and pharmacodynamics of pure curcumin (CUR) alone in humans. These studies have shown that systemic exposure to curcumin-containing products at doses of up to 8,000 mg /day was safe and tolerable and did not cause serious adverse events. In these studies, the peak serum concentrations ranged from 47 ng/mL (at a dose of 200 mg of oral curcumin daily) to 1,380 ng/mL (at a dose of 8,000 mg of oral curcumin daily).[1,2,3,4,5,6]
These concentrations refer to total curcumin, meaning that studies do not differentiate between free (unconjugated) curcumin and curcumin conjugated with glucuronic acid or sulfate. Conjugated curcumin is the more abundant metabolite in circulation. While studies indicate that conjugated curcumin is less bioactive than free curcumin, there are also indications for the enzymatic release of free curcumin from the conjugated forms at sites of inflammation.[7,8]
The assessment of curcuminoid bioavailability, including that of CUR, is confounded by the pronounced metabolic and (photo)chemical instability of these compounds. Because of the varying preparations, formulations, and doses of intervention materials tested in the phase I clinical trials, it is unclear which curcumin-containing products and doses of CUR and/or other constituents of Curcuma longa are required to produce a clinically significant modulation of biomarkers or even clinical outcomes. The general consensus that the plasma levels of CUR required to achieve any biological effects in patients are much higher than what has been observed clinically to date. Studies have directly compared the bioavailability of unformulated curcumin-containing preparations with CUR that is formulated for enhanced bioavailability. These studies have consistently shown an increase in plasma levels using formulated CUR; however, these levels are still relatively low and do not exceed therapeutically insufficient concentrations.[9,10]
Cancer Prevention and Treatment of Precancerous Lesions
Investigations into products that may aid in the prevention of cancer and the treatment of precancerous lesions are important for the development of early intervention strategies and treatments. A few studies have investigated the potential clinical benefit of curcumin -containing products, and other studies are under way (refer to ClinicalTrials.gov).
Researchers have explored curcumin's potential in curcumin-containing products for the prevention of colon cancer through its effects on precancerous lesions.
Published results (curcumin-containing product for prevention of colon cancer):
Head and Neck Cancer
Treatment of patients with oral leukoplakia using a curcumin-containing product was investigated in a randomized trial.
Published results (curcumin-containing product to treat oral leukoplakia):
The effect of a curcumin-containing product was investigated in patients with monoclonal gammopathy of undetermined significance (MGUS) or smoldering multiple myeloma ( SMM).
Published results (effectiveness of curcumin-containing product on MGUS and SMM):
Hepatoma (Liver Cancer)
The efficacy and safety of curcumin-containing products have been studied in patients with nonalcoholic fatty liver disease (NAFLD).
Published results (effectiveness of curcumin-containing product on NAFLD):
Based on these findings, the authors suggested that curcumin-containing products, at higher dosages, might have a favorable effect on patients with NAFLD.
Biomarkers have long been used to identify and understand the etiology of various diseases. In cancer research, there are different types of cancer biomarkers. Prognostic biomarkers determine the likely outcome of the disease and if further treatment is warranted and predictive biomarkers ascertain the likelihood the disease will respond to treatment.
Five clinical studies have been performed to evaluate the effects of supplementation with curcumin -containing products on predictive biomarkers in patients with different types of cancer. Various biomarkers from these studies were evaluated as potential efficacy measures to ascertain the usefulness of curcumin-containing products alone and as an adjunctive therapy. Different curcumin-containing products were used. Curcuminoid doses used in these studies ranged from 20 mg/day to 3,000 mg/day. One of the studies did not identify the amount of curcuminoids administered, but used 5 g of turmeric powder dissolved in 150 mL of milk 3 times/day.
The main biomarkers used in these studies were serum levels of the following:
Results from four of the studies indicated an association between a positive change in a biomarker and patient outcome as follows:
However, another study found no statistically significant difference between comparison groups when accounting for the observed biomarker, PGE2. Additionally, a different study found no significant change in GPx.
Another study conducted using a proprietary lecithin delivery system of a curcumin-containing product (500 mg tablet) given 3 times/day found that curcumin-containing product supplementation consistently improved oxidative status in patients who received chemotherapy and radiation therapy.
Curcumin-Containing Products Alone
A few case reports have been published that suggest a possible antitumor effect of curcumin-containing products.
Published results (possible antitumor effect of curcumin-containing product):
Given that this disease is known to frequently undergo spontaneous involution, the therapeutic activity of the curcumin-containing product in this case should be questioned; however, the authors of the report indicated that this patient's tumor had some signs that suggested an adverse prognosis.
Imatinib and Curcumin-Containing Products
Imatinib and curcumin-containing products have been studied in patients with metastatic adenoid cystic carcinoma (ACC).
Published results (treatment of c-kit –positive metastatic ACC with imatinib and a curcumin-containing product):
Given the known activity of imatinib against c-kit–positive tumors, the contribution of curcumin-containing products to the efficacy of this patient's treatment regimen is unclear.
Docetaxel and Curcumin-Containing Products
Two studies have explored the efficacy, tolerability, and feasibility of docetaxel plus curcumin-containing products in the treatment of cancer.[29,30]
Published results (efficacy of docetaxel and a curcumin-containing product):
A multicenter, phase II, randomized, double-blind study was initiated at the same institution in France and compared docetaxel plus a curcumin-containing product with docetaxel plus placebo in the first-line treatment of patients with metastatic castration-resistant prostate cancer. The study was terminated for futility in view of results from the interim analysis (NCT02095717).
Gemcitabine and Curcumin-Containing Products
Three studies investigated the efficacy and safety of variable formulations and doses of curcumin-containing products in combination with gemcitabine. All studies administered gemcitabine 1,000 mg/m2 IV weekly for 3 of 4 weeks, but differed in rate of gemcitabine administration.
Two research studies of first-line treatment in patients with advanced and metastatic pancreatic cancer (PC) showed differing results in tolerability and toxicity profiles.
Published results (gemcitabine and a curcumin-containing product):
The authors concluded that this combination of curcumin-containing products and gemcitabine is not feasible in this population of patients.
FOLFOX and Curcumin-Containing Products
A group from the United Kingdom conducted a combined phase I dose-escalation study and a phase IIA study of oral daily curcumin-containing products with folinic acid, fluorouracil, and oxaliplatin (FOLFOX) (CUFOX) in patients with metastatic colorectal cancer to assess safety, tolerability, and a suitable dose of curcumin.[34,35] Both studies used the same curcumin-containing product.
Published results (FOLFOX and a curcumin-containing product):
One study examined the potential effect of curcumin on the quality of life (QOL) of cancer patients (N = 80) with solid tumors, predominantly gastric, colorectal, and breast cancer. All patients received standard treatment for their respective cancers while enrolled in the study. Patients were randomly assigned to receive either curcuminoids (180 mg /day) or matched placebo for 8 weeks. Curcuminoids were prepared with phosphatidylcholine to boost bioavailability. Meriva contains 20% curcuminoids; therefore, each patient was asked to take three 300 mg capsules per day (one capsule tid).
This study reported an overall increase in self-reported QOL in both groups, with greater improvement in the curcuminoid group. However, because of the higher baseline QOL values in the placebo group when compared with the curcuminoid group, it is difficult to interpret these results.
Cancer Therapy Side Effects
The effects of curcumin -containing products on radiation-induced dermatitis were investigated in three studies.[37,38,39] Two of the studies evaluated oral curcumin-containing products while one study assessed topical application of a curcumin-containing cream.
Published results (curcumin-containing products in the treatment of radiation-induced dermatitis):
Several studies evaluated the tolerability and efficacy of a curcuminoid-containing product by oral application (mouthwash) in the treatment of oral mucositis.[40,41] The studies used several objective outcome measures, including the World Health Organization's mucositis scale and Oral Mucositis Assessment Scale.
Published results (curcuminoid-containing products in the treatment of oral mucositis):
A proprietary lecithin delivery system of a curcuminoid-containing product given 3 times/day (500 mg tablet) was evaluated in a controlled study to assess its efficacy in alleviating the side effects of chemotherapy and radiation therapy in patients undergoing these treatments 1 month after surgery for their cancer (N = 160; 80 patients each in the chemotherapy group and the radiation therapy group). These groups were further divided into experimental and control groups, with 40 patients in each subgroup receiving Meriva or a comparable placebo tablet. In both the chemotherapy and radiation therapy groups, frequency and severity of reported symptoms were significantly lower in the Meriva group and no significant changes were reported in the control group.
Most clinical studies of curcuma-containing products have demonstrated few, if any, associated adverse effects. In one small study (N = 17) of patients who received a curcumin -containing product along with gemcitabine chemotherapy, about 30% of patients (N = 5) who received 8,000 mg/day of the curcumin-containing product discontinued the product because of intractable abdominal fullness. Two other patients had a dose reduction to 4,000 mg, also because of abdominal complaints. In this study, seven patients had grade 3 gastrointestinal toxicity and two patients had grade 2 gastrointestinal toxicity.
To assist readers in evaluating the results of human studies of integrative, alternative, and complementary therapies for cancer, the strength of the evidence (i.e., the levels of evidence) associated with each type of treatment is provided whenever possible. To qualify for a level of evidence analysis, a study must:
Separate levels of evidence scores are assigned to qualifying human studies on the basis of statistical strength of the study design and scientific strength of the treatment outcomes (i.e., endpoints) measured. The resulting two scores are then combined to produce an overall score. For an explanation of the scores and additional information about levels of evidence analysis of CAM treatments for cancer, refer to the PDQ summary on Levels of Evidence for Human Studies of Integrative, Alternative, and Complementary Therapies.
The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
General Information and History
Revised text to state that curcumin is a member of the diarylheptanoid class of natural products derived from the rhizome of Curcuma longa L., an East Indian plant, commonly called turmeric.
Added text to state that serum concentrations refer to total curcumin, meaning that studies do not differentiate between free (unconjugated) curcumin and curcumin conjugated with glucuronic acid or sulfate. Conjugated curcumin is the more abundant metabolite in circulation. While studies indicate that conjugated curcumin is less bioactive than free curcumin, there are also indications for the enzymatic release of free curcumin from the conjugated forms at sites of inflammation (cited Kunihiro et al. [J Nutr Biochem 2019] and Kunihiro et al. [J Nat Prod 2019] as references 7 and 8, respectively).
Revised text to state that the assessment of curcuminoid bioavailability, including that of CUR, is confounded by the pronounced metabolic and (photo)chemical instability of these compounds. Also added that the general consensus that the plasma levels of CUR required to achieve any biological effects in patients are much higher than what has been observed clinically to date. Studies have directly compared the bioavailability of unformulated curcumin-containing preparations with CUR that is formulated for enhanced bioavailability. These studies have consistently shown an increase in plasma levels using formulated CUR; however, these levels are still relatively low and do not exceed therapeutically insufficient concentrations (cited Schiborr et al. and Stohs et al. as references 9 and 10, respectively).
This section was extensively revised.
This summary is written and maintained by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ Editorial Boards in maintaining the PDQ summaries can be found on the About This PDQ Summary and PDQ® - NCI's Comprehensive Cancer Database pages.
Purpose of This Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the use of curcumin in the treatment of people with cancer.. It is intended as a resource to inform and assist clinicians in the care of their patients. It does not provide formal guidelines or recommendations for making health care decisions.
Reviewers and Updates
This summary is reviewed regularly and updated as necessary by the PDQ Integrative, Alternative, and Complementary Therapies Editorial Board, which is editorially independent of the National Cancer Institute (NCI). The summary reflects an independent review of the literature and does not represent a policy statement of NCI or the National Institutes of Health (NIH).
Board members review recently published articles each month to determine whether an article should:
Changes to the summaries are made through a consensus process in which Board members evaluate the strength of the evidence in the published articles and determine how the article should be included in the summary.
Any comments or questions about the summary content should be submitted to Cancer.gov through the NCI website's Email Us. Do not contact the individual Board Members with questions or comments about the summaries. Board members will not respond to individual inquiries.
Levels of Evidence
Some of the reference citations in this summary are accompanied by a level-of-evidence designation. These designations are intended to help readers assess the strength of the evidence supporting the use of specific interventions or approaches. The PDQ Integrative, Alternative, and Complementary Therapies Editorial Board uses a formal evidence ranking system in developing its level-of-evidence designations.
Permission to Use This Summary
PDQ is a registered trademark. Although the content of PDQ documents can be used freely as text, it cannot be identified as an NCI PDQ cancer information summary unless it is presented in its entirety and is regularly updated. However, an author would be permitted to write a sentence such as "NCI's PDQ cancer information summary about breast cancer prevention states the risks succinctly: [include excerpt from the summary]."
The preferred citation for this PDQ summary is:
PDQ® Integrative, Alternative, and Complementary Therapies Editorial Board. PDQ Curcumin (Curcuma, Turmeric) and Cancer. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/about-cancer/treatment/cam/hp/curcumin-pdq. Accessed <MM/DD/YYYY>.
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Last Revised: 2022-03-03
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