The use of coenzyme Q₁₀ as a treatment for cancer in humans has been investigated in only a limited manner. With the exception of a single randomized trial,[1] which involved 20 patients and tested the ability of coenzyme Q₁₀ to reduce the cardiotoxicity caused by anthracycline drugs, the studies that have been published consist of anecdotal reports, case reports, case series, and uncontrolled clinical studies.[2-7] Reviewed in [8-11]

In view of the promising results from animal studies, coenzyme Q₁₀ was tested as a protective agent against the cardiac toxicity observed in cancer patients treated with the anthracycline drug doxorubicin. It has been postulated that doxorubicin interferes with energy-generating biochemical reactions that involve coenzyme Q₁₀ in heart muscle mitochondria and that this interference can be overcome by coenzyme Q₁₀ supplementation.[3,12,13] Studies with adults and children, including the aforementioned randomized trial, have confirmed the decrease in cardiac toxicity observed in animal studies.[1-4]

The potential of coenzyme Q₁₀ as an adjuvant therapy for cancer has also been explored. In view of observations that blood levels of coenzyme Q₁₀ are frequently reduced in cancer patients,[14,15] Reviewed in [7,9,10] supplementation with this compound has been tested in patients undergoing conventional treatment. An open-label (nonblinded), uncontrolled clinical study in Denmark followed 32 breast cancer patients for 18 months.[5] The disease in these patients had spread to the axillary lymph nodes, and an unreported number had distant metastases. The patients received antioxidant supplementation (vitamin C, vitamin E, and beta carotene), other vitamins and trace minerals, essential fatty acids, and coenzyme Q₁₀ (at a dose of 90 mg /day), in addition to standard therapy (surgery, radiation therapy, and chemotherapy, with or without tamoxifen). The patients were seen every 3 months to monitor disease status (progressive disease or recurrence), and, if there was a suspicion of recurrence, mammography, bone scan, x-ray, or biopsy was performed. The survival rate for the study period was 100% (4 deaths were expected). Six patients were reported to show some evidence of remission; however, incomplete clinical data were provided, and information suggestive of remission was presented for only 3 of the 6 patients. None of the 6 patients had evidence of further metastases. For all 32 patients, decreased use of painkillers, improved quality of life, and an absence of weight loss were reported. Whether painkiller use and quality of life were measured objectively (e.g., from pharmacy records and validated questionnaires, respectively) or subjectively (from patient self-reports) was not specified.

In a follow-up study, 1 of the 6 patients with a reported remission and a new patient were treated for several months with higher doses of coenzyme Q₁₀ (390 and 300 mg/day, respectively).[6] Surgical removal of the primary breast tumor in both patients had been incomplete. After 3 to 4 months of high-level coenzyme Q₁₀ supplementation, both patients appeared to experience complete regression of their residual breast tumors (assessed by clinical examination and mammography). It should be noted that a different patient identifier was used in the follow-up study for the patient who had participated in the original study. Therefore, it is impossible to determine which of the 6 patients with a reported remission took part in the follow-up study. In the follow-up study report, the researchers noted that all 32 patients from the original study remained alive at 24 months of observation, whereas 6 deaths had been expected.[6]

In another report by the same investigators, 3 breast cancer patients were followed for a total of 3 to 5 years on high-dose coenzyme Q₁₀ (390 mg/day).[7] One patient had complete remission of liver metastases (determined by clinical examination and ultrasonography), another had remission of a tumor that had spread to the chest wall (determined by clinical examination and chest x-ray), and the third patient had no microscopic evidence of remaining tumor after a mastectomy (determined by biopsy of the tumor bed).

All 3 of the above-mentioned human studies [5-7] had important design flaws that could have influenced their outcome. Study weaknesses include the absence of a control group (i.e., all patients received coenzyme Q₁₀), possible selection bias in the follow-up investigations, and multiple confounding variables (i.e., the patients received a variety of supplements in addition to coenzyme Q₁₀, and they received standard therapy either during or immediately before supplementation with coenzyme Q₁₀). Thus, it is impossible to determine whether any of the beneficial results was directly related to coenzyme Q₁₀ therapy.

Anecdotal reports of coenzyme Q₁₀ lengthening the survival of patients with pancreatic, lung, rectal, laryngeal, colon, and prostate cancers also exist in the peer-reviewed, scientific literature.[4] The patients described in these reports also received therapies other than coenzyme Q₁₀, including chemotherapy, radiation therapy, and surgery.

Refer to the NCI Web site ¹ for a list of active clinical trials evaluating the use of coenzyme Q₁₀ in cancer patients.

References

1. Iarussi D, Auricchio U, Agretto A, et al.: Protective effect of coenzyme Q10 on anthracyclines cardiotoxicity: control study in children with acute lymphoblastic leukemia and non-Hodgkin lymphoma. Mol Aspects Med 15 (Suppl): s207-12, 1994.  [PUBMED Abstract]
   
   
2. Folkers K, Wolaniuk A: Research on coenzyme Q10 in clinical medicine and in immunomodulation. Drugs Exp Clin Res 11 (8): 539-45, 1985.  [PUBMED Abstract]
   
   
3. Cortes EP, Gupta M, Chou C, et al.: Adriamycin cardiotoxicity: early detection by systolic time interval and possible prevention by coenzyme Q10. Cancer Treat Rep 62 (6): 887-91, 1978.  [PUBMED Abstract]
   
   
4. Folkers K, Brown R, Judy WV, et al.: Survival of cancer patients on therapy with coenzyme Q10. Biochem Biophys Res Commun 192 (1): 241-5, 1993.  [PUBMED Abstract]
   
   
5. Lockwood K, Moesgaard S, Hanioka T, et al.: Apparent partial remission of breast cancer in 'high risk' patients supplemented with nutritional antioxidants, essential fatty acids and coenzyme Q10. Mol Aspects Med 15 (Suppl): s231-40, 1994.  [PUBMED Abstract]
   
   
6. Lockwood K, Moesgaard S, Folkers K: Partial and complete regression of breast cancer in patients in relation to dosage of coenzyme Q10. Biochem Biophys Res Commun 199 (3): 1504-8, 1994.  [PUBMED Abstract]
   
   
7. Lockwood K, Moesgaard S, Yamamoto T, et al.: Progress on therapy of breast cancer with vitamin Q10 and the regression of metastases. Biochem Biophys Res Commun 212 (1): 172-7, 1995.  [PUBMED Abstract]
   
   
8. Complementary treatments highlighted at recent meeting. Oncology (Huntingt) 13 (2): 166, 1999.  [PUBMED Abstract]
   
   
9. Folkers K: Relevance of the biosynthesis of coenzyme Q10 and of the four bases of DNA as a rationale for the molecular causes of cancer and a therapy. Biochem Biophys Res Commun 224 (2): 358-61, 1996.  [PUBMED Abstract]
   
   
10. Ren S, Lien EJ: Natural products and their derivatives as cancer chemopreventive agents. Prog Drug Res 48: 147-71, 1997.  [PUBMED Abstract]
    
    
11. Hodges S, Hertz N, Lockwood K, et al.: CoQ10: could it have a role in cancer management? Biofactors 9 (2-4): 365-70, 1999.  [PUBMED Abstract]
    
    
12. Usui T, Ishikura H, Izumi Y, et al.: Possible prevention from the progression of cardiotoxicity in adriamycin-treated rabbits by coenzyme Q10. Toxicol Lett 12 (1): 75-82, 1982.  [PUBMED Abstract]
    
    
13. Iwamoto Y, Hansen IL, Porter TH, et al.: Inhibition of coenzyme Q10-enzymes, succinoxidase and NADH-oxidase, by adriamycin and other quinones having antitumor activity. Biochem Biophys Res Commun 58 (3): 633-8, 1974.  [PUBMED Abstract]
    
    
14. Folkers K: The potential of coenzyme Q 10 (NSC-140865) in cancer treatment. Cancer Chemother Rep 2 4 (4): 19-22, 1974.  [PUBMED Abstract]
    
    
15. Folkers K, Osterborg A, Nylander M, et al.: Activities of vitamin Q10 in animal models and a serious deficiency in patients with cancer. Biochem Biophys Res Commun 234 (2): 296-9, 1997.  [PUBMED Abstract]
    
    

Glossary Terms

Treatment given after the primary treatment to increase the chances of a cure. Adjuvant therapy may include chemotherapy, radiation therapy, hormone therapy, or biological therapy.

An incomplete description of the medical and treatment history of one or more patients. Anecdotal reports may be published in places other than peer-reviewed, scientific journals.

A type of antibiotic that comes from certain types of Streptomyces bacteria. Anthracyclines are used to treat many types of cancer. Anthracyclines damage the DNA in cancer cells, causing them to die. Daunorubicin, doxorubicin, and epirubicin are anthracyclines.

A substance that protects cells from the damage caused by free radicals (unstable molecules made by the process of oxidation during normal metabolism). Free radicals may play a part in cancer, heart disease, stroke, and other diseases of aging. Antioxidants include beta-carotene, lycopene, vitamins A, C, and E, and other natural and manufactured substances.

A lymph node in the armpit region that drains lymph channels from the breast.

A substance found in yellow and orange fruits and vegetables and in dark green, leafy vegetables. The body can make vitamin A from beta carotene. Beta carotene is being studied in the prevention of some types of cancer. It is a type of antioxidant.

In living cells, chemical reactions that help sustain life and allow cells to grow.

The removal of cells or tissues for examination by a pathologist. The pathologist may study the tissue under a microscope or perform other tests on the cells or tissue. There are many different types of biopsy procedures. The most common types include: (1) incisional biopsy, in which only a sample of tissue is removed; (2) excisional biopsy, in which an entire lump or suspicious area is removed; and (3) needle biopsy, in which a sample of tissue or fluid is removed with a needle. When a wide needle is used, the procedure is called a core biopsy. When a thin needle is used, the procedure is called a fine-needle aspiration biopsy.

A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.

A technique to create images of bones on a computer screen or on film. A small amount of radioactive material is injected into a blood vessel and travels through the bloodstream; it collects in the bones and is detected by a scanner.

A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord.

Having to do with the heart.

Toxicity that affects the heart.

A detailed report of the diagnosis, treatment, and follow-up of an individual patient. Case reports also contain some demographic information about the patient (for example, age, gender, ethnic origin).

A group or series of case reports involving patients who were given similar treatment. Reports of case series usually contain detailed information about the individual patients. This includes demographic information (for example, age, gender, ethnic origin) and information on diagnosis, treatment, response to treatment, and follow-up after treatment.

Treatment with drugs that kill cancer cells.

The muscles, bones, and joints that make up the area of the body between the neck and the abdomen.

An x-ray of the structures inside the chest. An x-ray is a type of high-energy radiation that can go through the body and onto film, making pictures of areas inside the chest, which can be used to diagnose disease.

A substance found in most tissues in the body, and in many foods. It can also be made in the laboratory. It is used by the body to produce energy for cells, and as an antioxidant. It is being studied in the treatment of cancer and in the relief of side effects caused by some cancer treatments. Also called CoQ10, Q10, ubiquinone, and vitamin Q10.

The longest part of the large intestine, which is a tube-like organ connected to the small intestine at one end and the anus at the other. The colon removes water and some nutrients and electrolytes from partially digested food. The remaining material, solid waste called stool, moves through the colon to the rectum and leaves the body through the anus.

In a clinical trial, the group that does not receive the new treatment being studied. This group is compared to the group that receives the new treatment, to see if the new treatment works.

A currently accepted and widely used treatment for a certain type of disease, based on the results of past research. Also called conventional therapy.

A drug that is used to treat many types of cancer and is being studied in the treatment of other types of cancer. Doxorubicin comes from the bacterium Streptomyces peucetius. It damages DNA (the molecules inside cells that carry genetic information) and stops cells from growing. Rapidly growing tumor cells that take up doxorubicin may die. It is a type of anthracycline antitumor antibiotic. Also called Adriamycin PFS, Adriamycin RDF, doxorubicin hydrochloride, and Rubex.

A major component of fats that is used by the body for energy and tissue development.

A researcher in a clinical trial or clinical study.

Having to do with the larynx.

Cancer that has spread from the original (primary) tumor to the liver.

One of a pair of organs in the chest that supplies the body with oxygen, and removes carbon dioxide from the body.

The use of x-rays to create a picture of the breast.

Surgery to remove the breast (or as much of the breast tissue as possible).

The spread of cancer from one part of the body to another. A tumor formed by cells that have spread is called a “metastatic tumor” or a “metastasis.” The metastatic tumor contains cells that are like those in the original (primary) tumor. The plural form of metastasis is metastases (meh-TAS-tuh-SEEZ).

Too small to be seen without a microscope.

A measure of weight. A milligram is approximately 450,000 times smaller than a pound and 28,000 times smaller than an ounce.

A nutrient required to maintain health.

Small structures in a cell that are found in the cytoplasm (fluid that surrounds the cell nucleus). Mitochondria make most of the energy for the cell and have their own genetic material that is different from the genetic material found in the nucleus. Many diseases are caused by mutations (changes) in the DNA of mitochondria. Mitochondria are cell organelles.

Describes a clinical trial or other experiment in which the researchers know what treatments are being given to each study subject or experimental group. If human subjects are involved, they know what treatments they are receiving.

Closely monitoring a patient's condition but withholding treatment until symptoms appear or change. Also called active surveillance, expectant management, and watchful waiting.

Having to do with the pancreas.

Research using animals to find out if a drug, procedure, or treatment is likely to be useful. Preclinical studies take place before any testing in humans is done.

The original tumor.

Cancer that is growing, spreading, or getting worse.

A gland in the male reproductive system. The prostate surrounds the part of the urethra (the tube that empties the bladder) just below the bladder, and produces a fluid that forms part of the semen.

The overall enjoyment of life. Many clinical trials assess the effects of cancer and its treatment on the quality of life. These studies measure aspects of an individual’s sense of well-being and ability to carry out various activities.

The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that travels in the blood to tissues throughout the body. Also called irradiation and radiotherapy.

A study in which the participants are assigned by chance to separate groups that compare different treatments; neither the researchers nor the participants can choose which group. Using chance to assign people to groups means that the groups will be similar and that the treatments they receive can be compared objectively. At the time of the trial, it is not known which treatment is best. It is the patient's choice to be in a randomized trial.

By or having to do with the rectum. The rectum is the last several inches of the large intestine closest to the anus.

Cancer that has recurred (come back), usually after a period of time during which the cancer could not be detected. The cancer may come back to the same place as the original (primary) tumor or to another place in the body. Also called recurrent cancer.

A decrease in the size of a tumor or in the extent of cancer in the body.

A decrease in or disappearance of signs and symptoms of cancer. In partial remission, some, but not all, signs and symptoms of cancer have disappeared. In complete remission, all signs and symptoms of cancer have disappeared, although cancer still may be in the body.

Cancer cells that remain after attempts to remove the cancer have been made.

An error in choosing the individuals or groups to take part in a study. Ideally, the subjects in a study should be very similar to one another and to the larger population from which they are drawn (for example, all individuals with the same disease or condition). If there are important differences, the results of the study may not be valid.

In medicine, treatment that experts agree is appropriate, accepted, and widely used. Health care providers are obligated to provide patients with standard therapy. Also called best practice and standard of care.

Adding nutrients to the diet.

A procedure to remove or repair a part of the body or to find out whether disease is present. An operation.

A drug used to treat certain types of breast cancer in women and men. It is also used to prevent breast cancer in women who have had ductal carcinoma in situ (abnormal cells in the ducts of the breast) and are at a high risk of developing breast cancer. Tamoxifen is also being studied in the treatment of other types of cancer. It blocks the effects of the hormone estrogen in the breast. Tamoxifen is a type of antiestrogen. Also called Nolvadex and tamoxifen citrate.

A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echo patterns are shown on the screen of an ultrasound machine, forming a picture of body tissues called a sonogram. Also called ultrasound.

A clinical study that lacks a comparison (i.e., a control) group.

A key nutrient that the body needs in small amounts to grow and stay strong. Examples are vitamins A, C, and E.

A substance used in cancer prevention. It belongs to the family of drugs called tocopherols.

A type of high-energy radiation. In low doses, x-rays are used to diagnose diseases by making pictures of the inside of the body. In high doses, x-rays are used to treat cancer.