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Unclear or conflicting scientific evidence
Acupuncture: Acupuncture, or the use of needles to manipulate the "chi" or body energy, originated in China over 5,000 years ago. There has been limited research on acupuncture for cancer pain, and the research that was done was shown to have mixed results. More studies are needed to determine potential benefits. Evidence from several small studies supports the use of acupuncture at a specific point on the wrist (P6) which helps reduce the nausea and vomiting associated with chemotherapy. Electroacupuncture has been studied to treat vasomotor symptoms in breast cancer patients, but more studies are needed to determine its role.
Aloe: Transparent gel from the pulp of the meaty leaves of Aloe vera has been used topically for thousands of years to treat wounds, skin infections, burns, and numerous other dermatologic conditions. Preliminary research suggests that aloe may help prevent or aid in the regression of cancerous tumors. Additional research is needed in this area. Caution is advised when taking aloe supplements due to a number of adverse effects that may include a laxative effect, cramping, dehydration and drug interactions. Aloe should not be used in pregnancy or breastfeeding, unless otherwise directed by a doctor.
American pawpaw: Evidence supporting the use of the American pawpaw (Asimina triloba) tree for the treatment of cancer in humans is largely anecdotal and subjective. However, use in humans has reported minimal side effects, and evidence from animal and in vitro studies suggests that American pawpaw extract does have some anticancer activity. Pawpaw standardized extract has been used for 18 months in patients with various forms of cancer, but well-designed studies on the long-term effects of pawpaw extracts have not been conducted. Pawpaw should not be used in pregnancy or breastfeeding, unless otherwise directed by a doctor.
Antineoplastons: Antineoplastons are a group of naturally occurring peptide fractions, which were observed by Stanislaw Burzynski, MD, PhD in the late 1970s and found to be absent in the urine of cancer patients. There is inconclusive scientific evidence regarding the effectiveness of antineoplastons in the treatment of cancer. Several preliminary human studies (case series, phase I/II trials) have examined antineoplaston types A2, A5, A10, AS2-1, and AS2-5 for a variety of cancer types. It remains unclear if antineoplastons are effective, or what doses may be safe. Until better research is available, no clear conclusion can be drawn.
Arabinoxylan: Arabinoxylan is made by altering the outer shell of rice bran using enzymes from Hyphomycetes mycelia mushroom extract. Arabinoxylan has been found to improve immune reactions in diabetes and cancer patients. Arabinoxylan products may contain high calcium and phosphorus levels, which may be harmful for patients with compromised renal (kidney) function.
Aromatherapy: Healing with fragrant oils has been used for thousands of years. Aromatherapy is often used in people with chronic illnesses (frequently in combination with massage), with the intention to improve quality of life or well-being. There is not enough scientific evidence in this area to form a firm conclusion about the effectiveness of aromatherapy. Essential oils should not be used internally.
Art therapy: Art therapy involves the application of a variety of art modalities including drawing, painting, clay and sculpture. Art therapy enables the expression of inner thoughts or feelings when verbalization is difficult or not possible. Limited evidence suggests that family caregivers of cancer patients may benefit from art therapy to help them cope with the stress of care giving. Possible benefits include reduced stress, lowered anxiety, increased positive emotions and increased positive communication with cancer patients and healthcare professionals. Art therapy may also reduce pain and other symptoms in cancer patients. More studies are needed to determine how best to use this form of intervention with this population.
Astragalus: Astragalus (Astragalus membranaceus) has been used in Chinese medicine for centuries due to its immune enhancing properties. Although early laboratory and animal studies report increased immune cell function and reduced cancer cell growth associated with the use of astragalus, there is no reliable human evidence in these areas. A recent study reports that astragalus-based Chinese herbal medicine may increase the effectiveness of platinum-based chemotherapy when combined with chemotherapy. Astragalus is also sometimes used with the intention to reduce side effects of cancer treatments, such as fatigue and weight loss. Due to a lack of well-designed research, a firm conclusion cannot be drawn.
Bee pollen: Bee pollen is considered a highly nutritious food because it contains a balance of vitamins, minerals, proteins, carbohydrates, fats, enzymes, and essential amino acids. Research has found that bee pollen may reduce some adverse effects associated with cancer treatment. Additional studies are needed before a firm recommendation can be made. Caution is advised when taking bee pollen supplements as allergic reactions may occur in sensitive individuals. Bee pollen should not be used in pregnancy or breastfeeding, unless otherwise directed by a doctor.
Bitter melon: Bitter melon (Momordica charantia) is used in the traditional Ayurvedic form of medicine from India to lower blood sugar levels. Research has also found that bitter melon extracts may be beneficial in cancer therapies. MAP30, a protein isolated from bitter melon extract, is reported to possess anti-cancer effects in laboratory studies. Potential anti-cancer effects have not been studied appropriately in humans. Caution is advised when taking bitter melon supplements, as numerous adverse effects including blood sugar lowering and drug interactions are possible. Bitter melon should not be used in pregnancy or breastfeeding, unless otherwise directed by a doctor.
Black tea: Black tea (Camellia sinensis) is from the same plant as green tea, but is processed differently. Black tea usually contains more caffeine than green tea. Several studies have explored a possible association between regular consumption of black tea and rates of cancer in populations. This research has yielded conflicting results, with some studies suggesting benefits, and others reporting no effects. Laboratory and animal studies report that components of tea, such as polyphenols, have antioxidant properties and certain effects against tumors. However, effects in humans remain unclear, and these components may be more common in green tea rather than in black tea. Some animal and laboratory research suggests that components of black tea may actually be carcinogenic, or cancer causing, although effects in humans are not clear. Overall, the relationship of black tea consumption and human cancer remains undetermined.
Bromelain: Bromelain is a sulfur-containing proteolytic digestive enzyme that is extracted from the stem and the fruit of the pineapple plant (Ananas comosus). There is not enough information to recommend for or against the use of bromelain in the treatment of cancer, either alone or in addition to other therapies. One small study found that a bromelain supplement decreased tumor size in 12 breast cancer patients. Patients took the supplements for months to years. Bromelain may cause an increase in bleeding in sensitive individuals, including those taking blood thinning medications such as warfarin (Coumadin®).
Cat's claw: Originally found in Peru, the use of cat's claw (Uncaria tomentosa) has been said to date back to the Inca civilization, possibly as far back as 2,000 years. Cat's claw has anti-inflammatory properties, and several low-quality studies suggest that cat's claw may slow tumor growth. However, this research is early and has not identified specific types of cancer that may benefit; the results are not clear. A few studies suggest that cat's claw may also boost the immune system. Cat's claw may cause an increase in bleeding in sensitive individuals, including those taking blood thinning medications such as warfarin (Coumadin®).
Chaparral: Chaparral was used by the Native Americans for various health conditions. The chaparral component nordihydroguaiaretic acid (NDGA) has been evaluated as a treatment for cancer, but due to risk of toxicity it is considered unsafe and not recommended for use. Chaparral and NDGA have been associated with cases of kidney and liver failure, liver cirrhosis, kidney cysts, and kidney cancer in humans. In response to these reports, the U.S. Food and Drug Administration (FDA) removed chaparral from its "generally recognized as safe" (GRAS) list in 1970. Chaparral and NDGA are generally considered unsafe and are not recommended for use.
Copper: Copper is a mineral that occurs naturally in many foods, including vegetables, legumes, nuts, grains and fruits, as well as shellfish, avocado, and beef (organs such as liver). Preliminary research reports that lowering copper levels theoretically may arrest the progression of cancer by inhibiting blood vessel growth (angiogenesis). Copper intake has not been identified as a risk factor for the development or progression of cancer. Copper is potentially unsafe when used orally in higher doses than the RDA. Copper supplements should not be used if pregnant or breastfeeding, unless otherwise directed by a doctor.
Cranberry: Several laboratory studies have reported positive effects of proanthocyanidins, flavonoid components of cranberry (Vaccinium macrocarpon) and other fruits such as blueberries, grape seed, and pomegranate, on health. Based on a small amount of laboratory research, cranberry has been proposed for cancer prevention. Study is needed in humans before a recommendation can be made.
DHEA (Dehydroepiandosterone): DHEA (dehydroepiandrosterone) is an endogenous hormone (made in the human body), and secreted by the adrenal gland. DHEA serves as precursor to male and female sex hormones (androgens and estrogens). Initial research reports that the use of intravaginal DHEA may be safe, promoting the regression of low-grade cervical lesions. However, further study is necessary in this area before a firm conclusion can be drawn. Patients should not substitute the use of DHEA for more established therapies, and should discuss management options and follow-up with a primary healthcare professional or gynecologist. Caution is advised when taking DHEA supplements due to adverse effects and possible drug interactions. DHEA should not be used in pregnancy or breastfeeding, unless otherwise directed by a doctor.
Echinacea: The evidence from a small number of randomized trials evaluating efficacy of echinacea in the treatment of radiation-induced leukopenia (decrease in white blood cells) is equivocal. Studies have used the combination product Esberitox®, which includes extracts of echinacea (Echinacea purpurea and pallida) root, white cedar(Thuja occidentalis) leaf, and wild indigo (Baptisia tinctoria) root.
Essiac®: Essiac® contains a combination of herbs, including burdock root (Arctium lappa), sheep sorrel (Rumex acetosella), slippery elm inner bark (Ulmus fulva), and Turkish rhubarb (Rheum palmatum). The original formula was developed by the Canadian nurse Rene Caisse (1888-1978) and is thought to be effective in cancer therapies, although currently there is no evidence for or against its use for any type of cancer. Different brands may contain variable ingredients, and the comparative effectiveness of these formulas is not known. None of the individual herbs used in Essiac® have been tested in rigorous human cancer trials, although some components have anti-tumor activity in laboratory studies. Caution is advised when taking Essiac® supplements, as numerous adverse effects, including drug interactions, are possible. Essiac® should not be used if pregnant or breastfeeding, unless otherwise directed by a doctor.
Focusing: Focusing (experiential therapy) is a method of psychotherapy that involves being aware of one's feelings surrounding a particular issue and understanding the meaning behind words or images conveyed by those feelings. Early evidence suggests focusing may improve the mood and body attitude in cancer patients. Firm recommendations cannot be made until well-designed clinical trials are available.
Folic acid: Folic acid or folate is a form of a water-soluble B vitamin needed for human health. Preliminary evidence surrounding the use of folate seems promising for decreasing the risk of breast, cervical, pancreatic and gastrointestinal cancer. However, currently there is insufficient evidence available to recommend folate supplementation for any type of cancer prevention or treatment. Please follow the advice of a qualified healthcare provider in this area. Folic acid may mask the symptoms of pernicious, aplastic, or normocytic anemias caused by vitamin B12 deficiency and may lead to neurological damage.
Gamma linolenic acid (GLA): GLA is an omega-6 essential fatty acid. Some laboratory and human studies indicate GLA may have anti-tumor activity and may be used as an adjunct agent to a chemotherapy regimen. Clinical trials have been conducted in treatments of breast, colorectal, and liver cancer. Caution is advised when taking GLA supplements, as numerous adverse effects including an increased risk of bleeding and drug interactions are possible. GLA should not be used if pregnant or breastfeeding, unless otherwise directed by a doctor.
Garlic: Preliminary human studies suggest that regular consumption of garlic (Allium sativum, particularly aged garlic) may reduce the risk of developing several types of cancer. Some studies use multi-ingredient products so it is difficult to determine if garlic alone may play a beneficial role. Further well-designed human clinical trials are needed to conclude whether eating garlic or taking garlic supplements may prevent or treat cancer. Garlic may cause an increase in bleeding in sensitive individuals, including those taking blood thinning medications such as warfarin (Coumadin®).
Ginseng: Several human studies suggest that Asian ginseng (Panax ginseng) may reduce the risk and progression of various organ cancers, especially if ginseng powder or extract is used. Results may have been affected by other lifestyle choices in people who use ginseng, such as exercise or dietary habits. Asian ginseng is also reported to help protect against radiation damage, increase immunity and well-being, and decrease fatigue. Additional trials are necessary before a clear conclusion can be reached.
Green tea: Green tea is made from the dried leaves of Camellia sinensis, a perennial evergreen shrub. Green tea has a long history of use in health and longevity, dating back to China approximately 5,000 years ago. Although used for centuries to help prevent diseases, the relationship of green tea consumption and human cancer remains inconclusive. Evidence from well-designed clinical trials is needed before a firm recommendation can be made in this area.
Healing touch (HT): Preliminary data suggests HT may be of benefit in cancer patients for inducing relaxation and improving quality of life. However, due to weaknesses in design and the small number of studies, data is insufficient to make definitive recommendations. Studies with stronger designs are needed.
Hoxsey formula: "Hoxsey formula" is a misleading name because it is not a single formula, but rather a therapeutic regimen consisting of an oral tonic and topical (on the skin) preparation. The tonic is individualized for cancer patients based on general condition, location of cancer, and previous history of treatment. An ingredient that usually remains constant for every patient is potassium iodide. Other ingredients are then added and may include licorice, red clover, burdock, stillingia root, berberis root, pokeroot, cascara, Aromatic USP 14, prickly ash bark, and buckthorn bark. A red paste may be used, which tends to be caustic (irritating), and contains antimony trisulfide, zinc chloride, and bloodroot. A topical yellow powder may be used, and contains arsenic sulfide, talc, sulfur, and a "yellow precipitate." A clear solution may also be administered, and contains trichloroacetic acid. There are no well-designed human studies available evaluating the safety or effectiveness of Hoxsey formula. Caution is advised when taking the Hoxsey formula supplements, as numerous adverse effects including an increased risk of drug interactions are possible. Hoxsey formula should not be used if pregnant or breastfeeding, unless otherwise directed by a doctor.
Hydrazine sulfate: Hydrazine is an industrial chemical marketed as having the potential to repress weight loss and cachexia (muscle wasting) associated with cancer, and to improve general appetite status. However, in large randomized controlled trials, hydrazine has not been proven effective for improving appetite, reducing weight loss or improving survival in adults. The National Cancer Institute (NCI) sponsored studies of hydrazine sulfate that claimed efficacy in improving survival for some patients with advanced cancer. Trial results found that hydrazine sulfate did not prolong survival for cancer patients. The U.S. Food and Drug Administration (FDA) has received requests from individual physicians for approval to use hydrazine sulfate on a case-by-case "compassionate use" basis on the chance that patients with no other available effective therapy might benefit. The overall controversy in the use of hydrazine sulfate is ongoing, and relevance to clinical practice is unknown. The use of hydrazine sulfate needs to be evaluated further before any recommendations can be made. Side effects have been reported, including nausea, vomiting, and diarrhea.
Iodine: Iodine is an element (atomic number 53), which is required by humans for the synthesis of thyroid hormones (triiodothyronine/T3 and thyroxine/T4). The potential role of non-radioactive iodine in cancer care remains unknown. Antioxidant and anti-tumor effects have been proposed based on laboratory research. In contrast, some scientists have asserted that tumors may uptake more iodine than normal tissues. Povidone-iodine solutions have been used as a part of alternative cancer regimens, such as the Hoxsey formula. Preliminary study has also indicated povidone-iodone solution as a potential rectal washout for rectal cancer. Overall, no clear conclusion can be drawn based on the currently available evidence. Iodine should not be used in pregnancy or breastfeeding, unless otherwise directed by a doctor.
Lycopene: High levels of lycopene are found in tomatoes and in tomato-based products. Tomatoes are also sources of other nutrients such as vitamin C, folate, and potassium. Several laboratory and human studies examining tomato-based products and blood lycopene levels suggest that lycopene may be associated with a lower risk of developing cancer and may help stimulate the immune system.
Maitake mushroom: Maitake is the Japanese name for the edible fungus Grifola frondosa. Maitake has been used traditionally both as a food and for medicinal purposes. Early studies in the laboratory as well as in humans suggest that beta-glucan extracts from maitake may increase the body's ability to fight cancer. However, these studies have not been well designed, and better research is needed before the use of maitake for cancer can be recommended.
Milk thistle: Milk thistle (Silybum marianum) has been used medicinally for over 2,000 years, most commonly for the treatment of liver and gallbladder disorders. There are early reports from laboratory experiments that the components silymarin and silibinin found in milk thistle may reduce the growth of human breast, cervical, and prostate cancer cells. This research is too early to determine firm conclusions, and the effects have not been shown in high-quality human trials.
Mistletoe: Mistletoe is one of the most widely used unconventional cancer treatments in Europe. Extracts have been studied for a variety of human cancers including bladder, breast, cervical, CNS, colorectal, head and neck, liver, lung, lymphatic, ovarian, and renal (kidney) cancers as well as melanoma and leukemia. However, efficacy has not been conclusively proven for any one condition. In fact, some studies have shown lack of efficacy of certain preparations for a variety of cancers. Larger, well-designed clinical trials are needed. Caution is advised when taking mistletoe supplements, as numerous adverse effects including nausea, vomiting, and drug interactions are possible. Mistletoe should not be used if pregnant or breastfeeding, unless otherwise directed by a doctor.
Moxibustion: Moxibustion is a healing technique employed across the diverse traditions of acupuncture and oriental medicine for over 2,000 years. Moxibustion uses the principle of heat to stimulate circulation and break up congestion or stagnation of blood and chi. Moxibustion is more closely related to acupuncture as it is applied to specific acupuncture points. More studies are needed to determine its exact role.
Psychotherapy: Psychotherapy is an interactive process between a person and a qualified mental health professional (psychiatrist, psychologist, clinical social worker, licensed counselor, or other trained practitioner). There is good evidence that psychotherapy can enhance cancer patients' quality of life by reducing emotional distress and aiding in coping with the stresses and challenges of cancer. Therapy may be supportive-expressive therapy, cognitive therapy or group therapy. Studies conflict on whether therapy improves self-esteem, death anxiety, self-satisfaction, etc. While some patients seek psychotherapy in hopes of extending survival, there is no conclusive evidence of effects on medical prognosis.
Reishi mushroom: Reishi (Ganoderma lucidum) has been shown to have antineoplastic and immunomodulatory effects in animal studies. One clinical trial and two case reports exist on advanced cancer patients using Ganopoly®, a Ganoderma lucidum polysaccharide extract. Results show improved quality of life and enhanced immune responses, which are typically reduced or damaged in cancer patients receiving chemotherapy and/or radiation therapy. Well-designed long-term studies are needed confirm these results and potential side effects.
Seaweed: Bladderwrack (Fucus vesiculosus) is a brown seaweed that grows on the northern coasts of the Atlantic and Pacific oceans, and the North and Baltic seas. Bladderwrack appears to suppress the growth of various cancer cells in animal and laboratory studies. However, currently there are no reliable human studies available to support a recommendation for use in cancer. Caution is advised when taking bladderwrack supplements, as numerous adverse effects including an increased risk of drug interactions are possible. Bladderwrack should not be used if pregnant or breastfeeding, unless otherwise directed by a doctor.
Selenium: Selenium is a trace mineral found in soil, water, and some foods. It is an essential element in several metabolic pathways. Several studies suggest that low levels of selenium (measured in the blood or in tissues such as toenail clippings), may be a risk factor for developing cancer, particularly prostate cancer. Population studies suggest that people with cancer are more likely to have low selenium levels than healthy matched individuals, but in most cases it is not clear if the low selenium levels are a cause or merely a consequence of disease. It remains unclear if selenium is beneficial in the treatment of any type of cancer.
Shark cartilage: For several decades, shark cartilage has been proposed as a cancer treatment. Studies have shown shark cartilage or the shark cartilage product AE-941 (Neovastat®) to block the growth of new blood vessels, a process called "anti-angiogenesis," which is believed to play a role in controlling the growth of some tumors. There have also been several reports of successful treatments of end-stage cancer patients with shark cartilage, but these have not been well-designed nor did they include reliable comparisons to accepted treatments.
Many studies have been supported by shark cartilage product manufacturers, which may influence the results. In the United States, shark cartilage products cannot claim to cure cancer, and the U.S. Food and Drug Administration (FDA) has sent warning to companies ensuring they would not promote the products in this way. Without further evidence from well-designed human trials, it remains unclear if shark cartilage is of any benefit in cancer and patients are advised to check with their doctor and pharmacist before taking shark cartilage.
Shiitake mushroom: Shiitake (Lentinus edodes) has been taken orally to boost the immune system, decrease cholesterol levels, and for anti-aging purposes. Lentinan, derived from shiitake, has been injected as an adjunct treatment for cancer and HIV infection. Laboratory, animal and human studies of lentinan have shown positive results in cancer patients when used in addition to chemotherapy drugs. Further well-designed clinical trials on all types of cancer are required to confirm these results.
Soy: Shiitake (Lentinus edodes) has been taken orally to boost the immune system, decrease cholesterol levels, and for anti-aging purposes. Lentinan, derived from shiitake, has been injected as an adjunct treatment for cancer and HIV infection. Laboratory, animal and human studies of lentinan have shown positive results in cancer patients when used in addition to chemotherapy drugs. Further well-designed clinical trials on all types of cancer are required to confirm these results.
Transcutaneous electrical nerve stimulation (TENS): Transcutaneous electrical nerve stimulation (TENS) is a non-invasive technique in which a low-voltage electrical current is delivered through wires from a small power unit to electrodes located on the skin. Although TENS has been used with some success in pain associated with cancer, there is not enough reliable evidence to draw a firm conclusion in this area.
Thiamin (Vitamin B1): Thiamin deficiency has been observed in some cancer patients, possibly due to increased metabolic needs, but it is not clear if these low levels of thiamin are beneficial. Currently, it remains unclear if thiamin supplementation plays a role in the management of any cancers.
Traditional Chinese Medicine (TCM): The ancient Chinese philosophy of Taoism provided the basis for the development of Chinese medical theory. TCM uses over 120 different herbs for cancer depending on which type is being treated and its cause. Studies have reported significant benefits such as reducing tumors, reducing treatment side effects and improved response to treatment. More studies of stronger design are needed before TCM can be recommended as an adjunct to cancer treatment; however, centuries of traditional use in cancer cannot be discounted.
Turmeric: Turmeric (Curcuma longa) is commonly used for its anti-inflammatory properties. Several early animal and laboratory studies report anti-cancer (colon, skin, breast) properties of curcumin. Many mechanisms have been considered, including antioxidant activity, anti-angiogenesis (prevention of new blood vessel growth), and any direct effects on cancer cells. Currently, it remains unclear if turmeric or curcumin has a role in preventing or treating human cancers. There are several ongoing studies in this area. Turmeric may cause an increase in bleeding in sensitive individuals, including those taking blood thinning medications such as warfarin (Coumadin®).
Vitamin C (ascorbic acid): Dietary intake of fruits and vegetables high in vitamin C has been associated with a reduced risk of various types of cancer in population studies (particularly cancers of the mouth, esophagus, stomach, colon, or lung). However, it is not clear that it is specifically the vitamin C in these foods that is beneficial, and vitamin C supplements have not been found to be associated with this protective effect. Experts have recommended increasing dietary consumption of fruits and vegetables high in vitamin C, such as apples, asparagus, berries, broccoli, cabbage, melon (cantaloupe, honeydew, watermelon), cauliflower, citrus fruits (lemons, oranges), fortified breads/grains/cereal, kale, kiwi, potatoes, spinach, and tomatoes. Vitamin C has a long history of adjunctive use in cancer therapy, and although there have not been any definitive studies using intravenous (or oral) vitamin C, there is evidence that it has benefit in some cases. Better-designed studies are needed, and when used in large doses (greater than 2 grams), it may cause diarrhea and gastrointestinal upset.
Yoga: Yoga is an ancient system of relaxation, exercise, and healing with origins in Indian philosophy. Several studies in cancer patients report enhanced quality of life, lower sleep disturbance, decreased stress symptoms and changes in cancer-related immune cells after patients received relaxation, meditation and gentle yoga therapy. Yoga is not recommended as a sole treatment for cancer but may be helpful as an adjunct therapy.
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