Cancer and the Immune System: The Role of Natural Medicine


Optimal immune function is essential in both fighting cancer among patients who have active cancer, as well as for the prevention of cancer in patients at high risk. Natural therapies that enhance immune function include medicinal mushrooms, Astragalus, probiotics, vitamin D, intravenous vitamin C, and mistletoe therapy.


Cancer is thought to affect approximately 2 in 5 Canadians at some point during their lifetime (1). While cancer can be an intimidating diagnosis, it is important for individuals to be aware of adjunctive strategies at their disposal to help fight this diagnosis. One of the key avenues is strengthening immune function so the body can target cancer cells more effectively.

Effective immune function is essential in both fighting cancer among patients who actively have cancer, as well as for the prevention of cancer in patients at high risk. It is the role of specialized immune cells such as lymphocytes, T-helper cells, and natural killer (NK) cells to carry on ongoing immune surveillance. In other words, these cells “seek out and destroy” cancer cells as they arise in the body (2,3). Cancer, being an ever-adapting disease, survives in part by suppressing this ability (3). Inhibitory immune cells such as regulatory T-cells (Tregs) may infiltrate the tumour and suppress the ability of other effector immune cells to kill cancer cells.3 In addition, one of the most common and problematic side effects of chemotherapy also involves immune suppression.

On the other hand, among patients with cancer, it has been shown that those with relatively higher counts of lymphocytes fare better in terms of cancer treatment outcomes and survival (4.5). Clearly the immune system is the key to optimizing cancer treatments, and conventional medicine recognizes this as well, as may be seen in the development of new immunotherapeutic drugs that target various aspects of the immune system (3).

Naturopathic cancer care utilizes several types of therapies that enhance immune function, both in the aims of treating and/ or preventing cancer. Some of these include:

Medicinal mushrooms such as Coriolus versicolor (turkey tail) and Ganoderma lucidum (reishi mushroom) have been shown to help offset the immune suppressing effects of chemotherapy, and improve survival among patients with lung cancer, breast cancer, gastric cancer and colorectal cancer (6,7,8). It is important that a good quality mushroom extract is used, and should be hot water extracted. This process liberates the polysaccharides that are responsible for mushrooms’ therapeutic effects, and is the form used traditionally in Asia as well as in clinical trials (6).

Astragalus membranaceous is an herb used extensively in Chinese medicine as well as Western herbalism that has been shown to boost immune function. In patients with non-small cell lung cancer (NSCLC), astragalus lowered the toxic effect of radiation therapy on white blood cell counts and improved survival (9).

Probiotics are important gut-based immune modulators. One study of patients with colorectal cancer found that supplementation probiotics beginning one day before surgery and continuing for 15 days afterward, resulted in an overall decrease in all major post-operative complications, including infection, compared to placebo (10). Patients receiving probiotics had shorter hospital stays and lower levels of inflammatory cytokines, such as TNF and IL-6 (10).

Probiotics also help improve the eradication rates of infectious agents associated with cancer risk, such as human papilloma virus (HPV) and Helicobacter pylori (H. pylori) bacteria (11,12). HPV infection is associated with cervical dysplasia (a precursor to cervical cancer), as well as oral cancers, while H. pylori is associated with gastric cancers.

Vitamin D is an important immune modulating nutrient in which many Canadians are deficient (13). Vitamin D is also important in regulating healthy cell division (14). It is generally accepted that blood levels of the marker 25(OH)D should be equal to or above 75nmol/L. Studies have shown that being low in vitamin D elevates risk of several types of cancers, while being sufficient in vitamin D is associated with better treatment outcomes (15, 16, 17).

Finally, two more advanced, injectable therapies that stimulate immune function are intravenous vitamin C therapy and mistletoe therapy (18, 19, 20). These may be used as adjuncts to chemotherapy and/ or radiation in patients with active cancer, or to prevent recurrence in patients who have completed treatment. IV vitamin C has been shown to reduce side effects of chemotherapy, reduce tumor markers such as prostate specific antigen (PSA) and inflammatory cytokines, and may improve survival in patients with cancer (18). Mistletoe therapy has been shown to reduce immune suppression associated with chemotherapy, improve quality of life, and extend survival in patients with breast and gynecological cancers (19, 20).

Please note that individuals with cancer should consult a knowledgeable, licensed naturopathic doctor to determine what treatments may be most appropriate for them, and to minimize risk of interactions with standard treatments.


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