People with cancer want to do everything they can to combat the disease, manage its symptoms, and cope with the side effects of treatment. Many turn to practices known collectively as CAM(complementary and alternative medicine)—for example, botanical (herbal) and other dietary supplements, acupuncture, massage, and yoga.
This fact sheet provides an introductory overview of CAM and cancer, including a summary of "what the science says." The fact sheet is mainly for people who have been diagnosed with cancer, and for families and friends of people who are being treated for or recovering from cancer. This fact sheet also takes a brief look at research on some of the dietary supplements that people use in hope of preventing cancer.
- CAM therapies should never be used as a replacement for conventional cancer care or as a reason to postpone seeing a doctor about any problem.
- There is limited scientific evidence suggesting that some CAM approaches may be useful in managing some symptoms of cancer and side effects of treatment. At present, there is no convincing evidence regarding CAM use in preventing or curing cancer.
- Before using any CAM therapy, people who have been diagnosed with cancer should talk with the doctors who treat their condition—to make sure that all aspects of their cancer care work together. Be aware that some dietary supplements can interfere with standard cancer treatments.
- Cancer patients need to make informed decisions about using CAM. The National Center for Complementary and Alternative Medicine (NCCAM) and the National Cancer Institute have written a brochure that can help: Thinking About Complementary and Alternative Medicine: A Guide for People with Cancer (NCI).
- In evaluating CAM therapies, people should be wary of extreme claims. Remember: if it sounds too good to be true—for example, claims that a CAM therapy can cure cancer—it usually is.
Cancer is a group of related diseases that occur when abnormal cells divide without control. Cancer cells can invade and damage nearby tissues and spread to distant parts of the body through the blood and the lymph systems. Although cancer remains the second leading cause of death in the United States, improvements in detection, diagnosis, and treatment have increased the survival rate for many types of cancer.
Detailed information on cancer is available from the National Cancer Institute.
Complementary and alternative medicine—commonly known as CAM—refers to a group of diverse medical and health care systems, practices, and products that are not generally considered part ofconventional medicine. People use CAM in addition to conventional medicine or, sometimes, in place of it. (Integrative medicine is an emerging concept that refers to combining conventional and CAM treatments for which there is evidence of safety and effectiveness.)
Some CAM therapies are beginning to find a place in cancer treatment—not as cures or alternatives to conventional treatment, but as complementary approaches that may help patients feel better.
CAM Use for Cancer
Many people who have been diagnosed with cancer use CAM. In 2002 and 2007, the National Health Interview Survey (NHIS) included comprehensive questions on CAM use by Americans. According to the 2007 NHIS, more than one-third of adults (about 38 percent) had used some form of CAM. A special analysis of 2002 NHIS data found that CAM use was more prevalent among people with a prior diagnosis of cancer. About 40 percent of cancer survivors reported using CAM; 18 percent had used multiple CAM therapies. CAM use rates for cancer survivors were similar to rates for people with other chronic illnesses such as arthritis, asthma, inflammatory bowel disease, irritable bowel syndrome, or ulcers. The most popular CAM therapies among cancer survivors were herbal and other natural products (20 percent), deep breathing (14 percent), and meditation (9 percent).
Other surveys also find that CAM use is common among people who have been diagnosed with cancer, although estimates of use vary widely. Studies have found that cancer patients who use CAM usually do not expect it to cure their disease. Rather, they hope to boost their immune system, relieve pain, or manage the side effects they are experiencing from the disease or its treatment. Few cancer patients say they use CAM because they are disappointed with their standard treatment. Their motivation is more likely to be a perceived benefit from CAM, a desire to feel more in control of their health, or a strong belief in CAM.
Surveys also indicate that use of vitamin and mineral supplements is widespread among cancer patients and survivors, but many physicians are unaware that their cancer patients are using these supplements.
What the Science Says About CAM and Cancer
To date, relatively little is known about the safety and effectiveness of CAM therapies that people may use for cancer. However, some CAM therapies have undergone careful evaluation, and many more studies are being carried out every year. In 2009, the Society for Integrative Oncology issued evidence-based clinical practice guidelines for doctors to consider when incorporating complementary therapies in the care of cancer patients.
Researchers are also evaluating CAM approaches that people sometimes use in hope of reducing their risk of getting cancer. These studies have focused on various vitamin and mineral supplements.
A comprehensive summary of research on CAM and cancer is beyond the scope of this fact sheet. The following sections provide an overview of research status, highlighting results from a few reviews and studies in the areas of cancer prevention, treatment, and management of symptoms and side effects.
CAM for Cancer Prevention
Although researchers continue to investigate the possible role of vitamin and mineral supplements in preventing cancer, available evidence does not support taking these supplements for this purpose:
- A 2007 review of clinical trials looking at the effectiveness of multivitamin/mineral supplements for cancer prevention found that few such trials have been conducted, and that the results of most large-scale trials have been mixed. According to the National Cancer Institute, the following supplements have been studied but have not been shown to lower the risk of cancer: vitamins B6, B12, E, and C; beta-carotene; folic acid; and selenium.
- Two large-scale studies—the Alpha-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Trial and the Beta-Carotene and Retinol Efficacy Trial (CARET)—found evidence that supplements containing beta-carotene increased the risk of lung cancer among smokers.
- An independent review of data from the Selenium and Vitamin E Cancer Prevention Trial (SELECT), funded by the National Cancer Institute, NCCAM, and other agencies at the National Institutes of Health (NIH), showed that selenium and vitamin E supplements, taken either alone or together, did not prevent prostate cancer.
- A 2003 Agency for Healthcare Research and Quality (AHRQ) review found little evidence of cancer prevention benefits from three antioxidants (vitamins C and E, and coenzyme Q10).
- A 2008 review of 20 clinical trials found no convincing evidence that antioxidant supplements prevent gastrointestinal cancer, but did find indications that some might actually increaseoverall mortality. The review looked at beta-carotene, selenium, and vitamins A, C, and E. Selenium alone demonstrated some preventive benefits.
- The National Cancer Institute notes research indicating that higher intake of calcium may be associated with reduced risk of colorectal cancer, but concludes that the available evidence does not support taking calcium supplements to prevent colorectal cancer.
A 2009 review of 51 studies with more than 1.6 million participants found "insufficient and conflicting" evidence regarding an association between green tea consumption and cancer prevention. Most of the research to date has consisted of epidemiological (observational) studies carried out in Asia, and the authors of the review point to the need for well-designed clinical trials to evaluate green tea—in liquid and capsule form—for cancer prevention.
Additional information on cancer prevention is available from the National Cancer Institute.
CAM for Cancer Treatment
Botanical supplements are among the most common CAM approaches used by cancer patients. A 2008 review of the research literature concluded that some botanicals used in Ayurvedic medicineand traditional Chinese medicine may have a role in cancer treatment. However, scientific evidence is limited—much of the research on botanicals and cancer treatment is in the early stages. The review also notes that botanicals can have side effects and can interact with cancer drugs, blood thinners and other prescription drugs, and each other.
It is unclear whether the use of vitamin and mineral supplements by people who have been diagnosed with cancer is beneficial or harmful. For example, taking a daily multivitamin might improve the nutritional status of patients who cannot eat a healthful diet, but there is concern that some supplements might interfere with cancer treatment or increase the risk of a recurrence. Related studies have been inconsistent or inconclusive. Additional, well-designed research is needed to investigate how use of vitamin and mineral supplements by people with cancer relates to treatment efficacy, recurrence, survival, and quality of life.
While some research has reported benefits from taking antioxidants for cancer, there is not enough scientific evidence to support their use by cancer patients. A 2003 AHRQ review of cancer-related research on three antioxidants (vitamins C and E, and coenzyme Q10) found little scientific evidence of cancer treatment benefits. Patients' use of antioxidants while undergoing chemotherapy or radiation therapy has not been well studied. However, a 2008 review of published research suggests that antioxidant supplements may decrease the effectiveness of chemotherapy and radiation therapy.
CAM for Cancer Symptoms and Side Effects
Studies have found acupuncture to be useful in managing chemotherapy-associated vomiting in some cancer patients. Although research on acupuncture for cancer pain control and for management of other cancer symptoms is limited, some studies have shown beneficial effects that warrant further investigation. A 2008 evidence-based review of clinical options for managing nausea and vomiting in cancer patients noted electroacupuncture as an option to be considered.
Various studies also suggest possible benefits of CAM therapies such as hypnosis, massage, meditation, and yoga in helping cancer patients manage side effects and symptoms of the disease. For example, a study of 380 patients with advanced cancer concluded that massage therapy may offer some immediate relief for these patients, and that simple touch therapy (placing both hands on specific body sites)—which can be provided by family members and volunteers—may also be helpful. The study was conducted at 15 hospices in the Population-based Palliative Care Research Network.
A 2008 review of the research literature on botanicals and cancer concluded that although several botanicals have shown promise for managing side effects and symptoms such as nausea and vomiting, pain, fatigue, and insomnia, the scientific evidence is limited (the reviewers did not find sufficient evidence to recommend any specific treatment), and many clinical trials have not been well designed. As with use for cancer treatment, use of botanicals for symptom management raises concerns about interactions with cancer drugs, other drugs, and other botanicals.
NIH Research on CAM for Cancer
NCCAM funds numerous laboratory studies and clinical trials designed to evaluate the safety and effectiveness of CAM therapies for cancer-related uses. Recent NCCAM-supported clinical trials have been investigating:
- Flaxseed (alone and in combination with drug therapy) for treating breast cancer
- Massage for swelling of the arms and legs (lymphedema) related to breast cancer treatment
- Tai chi for physical fitness and stress in cancer survivors
- Yoga and qi gong for fatigue in breast cancer survivors.
In addition to NCCAM-funded research on cancer, the National Cancer Institute conducts many studies on CAM approaches for cancer through its Office of Cancer Complementary and Alternative Medicine (OCCAM), some of which are cofunded with NCCAM.
If You Have Been Diagnosed With Cancer and Are Considering CAM
- Gather information about the CAM product or therapy that interests you, and then discuss it with your health care providers. If you have been diagnosed with cancer, it is especially important to talk with your doctors before you use any CAM product or therapy. Some CAM products may interfere with standard treatment or may be harmful when used along with standard treatment. Examples of questions to ask include:
- What is known about the benefits and risks of this CAM product or therapy? Do the benefits outweigh the risks?
- What are the potential side effects?
- Will the CAM product or therapy interfere with conventional treatment?
- Can you refer me to a CAM practitioner?
- Do not use any CAM therapy as a replacement for conventional cancer care or as a reason to postpone seeing a doctor about any medical problem.
- Tell all your health care providers about any CAM products or practices you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care. For tips about talking with your health care providers about CAM, see NCCAM's Time to Talk campaign.
Safety: Some Precautions for Cancer Patients Considering CAM
Some dietary supplements can interfere with cancer treatments; for example, the herb St. John's wort may cause certain anticancer drugs not to work as well as they should, and high doses of vitamins (even vitamin C) may affect how chemotherapy and radiation work. There are also general safety cautions about dietary supplements to be aware of; for example, some products may contain ingredients that are not on the label. Related information is available from NCCAM at Using Dietary Supplements Wisely.
Complications from acupuncture are very rare, as long as the acupuncturist uses sterile needles and proper procedures. Because chemotherapy and radiation therapy weaken the body's immune system, cancer patients who are undergoing these therapies should be sure that the acupuncturist follows strict clean-needle procedures. The acupuncturist should use new disposable (single-use) needles for each patient.
Although massage therapy appears to be generally safe, cancer patients should consult the doctor who treats their cancer before they have a massage that involves deep or intense pressure. Any direct pressure over a tumor usually is discouraged.
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