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Beginner’s Guide to the Immune System and its Cancer Connection


  • As the first Integrative Hallmark of Cancer, the compromised immune system weakens the body’s defense against the onslaught of pathogens or the growth of cancer.
  • The immune system is spread throughout the body, present in various organs and tissues, including the bone marrow, thymus, and gastrointestinal (GI) tract.
  • Cancer cells can manipulate the immune system to support their growth.

With most acute infectious diseases, it is easy to connect the cause (pathogen) to the effect (symptoms). The same cannot be said for cancer. While some cancer cases can be directly associated with certain toxins, such as smoking to lung cancer and asbestos to mesothelioma, other types of cancers can sometimes appear to be random. But as we’ve learned more about the characteristics of cancer cells in recent years, less focus has been directed at what causes cancer to develop in the first place. Are these “random” cancer cases actually random, or do we simply not know their cause yet?

To address this gap in knowledge, we have recently proposed 11 Integrative Hallmarks of Cancer™ that form the foundation of our holistic, integrative approach to oncology. These Integrative Hallmarks summarize what science and clinical experience tell us today about the various factors that contribute to the increased risk, growth, and spread of cancer. Once we understand the “why” of cancer development, we can understand “how” to heal from it.

The 11 Integrative Hallmarks classify into four categories: Systemic Dysregulations, Environmental and Biological Influences, Emotional and Spiritual Imbalances, and Habits and Behaviors. The first Integrative Hallmark, the Compromised Immune System, falls in the category of Systemic Dysregulations. As we know, the immune system is a collection of the body’s defense mechanisms that protect it against foreign invaders such as bacteria, viruses, and parasites. Unlike other body systems that are located in a single region (like the respiratory system or GI tract), the immune system is not clustered in one area. The name says it all—the immune system is located all over the body in a complex network of organs, tissues, and cells. Each part has a unique function, including physical protection, immune cell production, or filtering bodily fluids.

The two main “factories” of immune cells are located in the bone marrow and the thymus (not to be confused with the thyroid!). The bone marrow is the spongy tissue inside your bones that produce both red and white blood cells, and the thymus is a little-known organ that sits between your lungs and produces specific immune cells, a type of white blood cell or lymphocyte, called T cells (1).

Diagram of human immune system with labels

The protective parts of the immune system tend to be located near entry points of the body or in areas frequently exposed to infection. The tonsils, which sit in the back of the throat, protect the mouth and nose from infection. The skin, in addition to acting as a physical barrier against pathogens, also produces immune cells called dendritic cells, which alert the immune system to foreign invaders (2). Lastly, the gut, the subject of intense research over the past two decades, has been found to contain 70% of the body’s immune system! (3) Perhaps this isn’t surprising considering the fact that food is a common source of pathogens and infections (remember the last time you had food poisoning?). Indeed, the entire surface of the gut is lined with lymphoid tissue, containing more immune cells than anywhere else in the body!

Other parts of the immune system are responsible for cleansing the blood and other bodily fluids. The lymph nodes are small, bean-shaped organs found throughout the body, including in the neck, armpits, and groin. They filter the lymph fluid that circulates throughout the body and contains immune cells that help to fight infection. While the lymph nodes take care of the lymph fluid, the spleen takes care of the blood. The spleen is located in the upper left side of your abdomen, near your stomach. It filters the blood, removes damaged or abnormal red blood cells, and stores immune cells called lymphocytes (1).

Outside of the primary immune organs, the immune system is divided into different cell types and immune responses, each with a distinct function. For more information on the mechanics of our body’s defense system, refer to our two-part blog series on immunomodulation.

As we’ve seen, the immune system helps detect foreign invaders such as viruses, bacteria, and parasites. But you may be wondering, does the immune system fight cancer? The answer is yes! The immune system protects us against both pathogens and cancer cells, and it’s the body’s first line of defense against cancer. A healthy immune system identifies and attacks abnormal cells before they can grow and divide to create a tumor. But even once a tumor has developed, the immune system still plays an important role by attacking the tumor and preventing it from spreading to other parts of the body. That’s why ensuring your immune system is in tip-top shape is critically important in both preventing cancer and healing from the disease.

To look at it another way, the body is like a garden, and the immune system is both the gardener and the wire fence around the garden. The fence protects your vegetables from squirrels and rabbits (like pathogens), and the gardener patrols the garden to ensure the weeds aren’t growing out of control (like cancer cells). But when a hole appears in the fence or the gardener gets called away to work overtime (just like chemotherapy, stress, or a poor diet compromises the immune system), the rabbits and weeds are free to wreak havoc.

With this in mind, you can see how chemotherapy and other immunocompromising factors are like bombs and tanks to the garden—although they eliminate the weeds, they also injure the plants and tear down the fence! Ideally, instead of weakening the immune system, we should focus on strengthening the immune system and directing it against the cancer cells. Bombs and tanks won’t help your garden grow better vegetables, but sunshine, fertilizer, and weeding will!

Of course, tuning up the immune system is not that simple, especially since cancer has developed many ways to evade the immune system. Some of the sneaky tactics cancer cells use to avoid the immune system include:

  • Releasing chemicals that suppress the immune system and prevent immune cell activation (4)
  • Causing chronic inflammation at the tumor site, which depresses the immune system and helps the cancer cells hide and grow (5)
  • Altering the surface antigens on the cancer cell to become “invisible” to the immune system (4)
  • Developing physical traits that act as barriers against immune cells (6)

Perhaps the most sneaky tactic of all is when cancer cells use the body’s own immune cells to trick the immune system. Cancer cells can recruit regulatory T cells to the site and trick them into preventing an immune response instead of eliciting an immune response (7).

So, does cancer weaken your immune system? Not necessarily. It’s more that cancer cells have a map and a list of instructions for exactly how to dodge and weave around the body’s obstacles. Cancer cells don’t operate independently of the body; they use the body to facilitate their growth and survival. This is why the biological terrain matters—just like the soil in the garden matters when growing fruits or vegetables, so the state of the body matters in health and cancer development. Instead of laser-focusing on the cancer cell, we should focus on tuning up the biological terrain (which includes the immune system) to make the body an inhospitable environment for cancer growth. Fortunately, a compromised immune system is not compromised for good—it simply needs direction and reprogramming.

Knowing the important connection between cancer and the immune system, it makes sense why immunotherapy is such a logical approach to cancer treatment. Immunotherapy uses the body’s own immune system to fight cancer by boosting its ability to recognize and attack abnormal cells like cancer cells. But immunotherapy is just one tool in a large arsenal that strengthen the biological terrain. At Hope4Cancer, tools like Sono-Photo Dynamic Therapy, Full-Body Hyperthermia, Hyperbaric Oxygen, Near Infrared Sauna, and the Garden Food Plan® improve the state of the entire body to (literally and figuratively) turn up the heat on cancer cells! By looking at all aspects of cancer development—body, mind, and spirit—we can discover the root cause of disease and map out a plan of healing.


1. Cleveland Clinic, Immune System: Parts and Common Problems. (2020).  

2. Haniffa, M., M. Gunawan, and L. Jardine, Human skin dendritic cells in health and disease. J Dermatol Sci, 2015. 77(2): p. 85-92.

3. Vighi, G., et al., Allergy and the gastrointestinal system. Clin Exp Immunol, 2008. 153 Suppl 1(Suppl 1): p. 3-6.

4. Kim, S.K. and S.W. Cho, The Evasion Mechanisms of Cancer Immunity and Drug Intervention in the Tumor Microenvironment. Front Pharmacol, 2022. 13: p. 868695.

5. Coussens, L.M., L. Zitvogel, and A.K. Palucka, Neutralizing tumor-promoting chronic inflammation: a magic bullet? Science, 2013. 339(6117): p. 286-91.

6. Nia, H.T., L.L. Munn, and R.K. Jain, Physical traits of cancer. Science, 2020. 370(6516).

7. Ohue, Y. and H. Nishikawa, Regulatory T (Treg) cells in cancer: Can Treg cells be a new therapeutic target? Cancer Sci, 2019. 110(7): p. 2080-2089.

6 thoughts on “Beginner’s Guide to the Immune System and its Cancer Connection

  1. My doctor wants me to go ahead with a prostate biopsy and then surgery if needed. I just feel against that in my spirit although that is ththink I will die if I don’t have it doene gold standard they tell us. No other information was given except , oh well I have several men who have had this surgery and do quite well. At this point is is probably advaned and they

    1. We are so sorry to hear all you are going through. This has to be such a difficult time for you. We are not able to give medical advice directly through our website or social media platforms. Please contact our admissions office at 888-544-5993 or go to and fill out the form so one of our admissions officers can get you a free consultation with our doctor.

  2. Good morning to all of you.
    First thing ive been following you through. My dearest friend who’ll be seeing you soon. I want the knowledge and understanding from all this awesome work you all are doing.I’m so very great ful she found you and want to be there with her.
    Thank you so very much for all you do.
    Been Jenkins

    1. Thank you for the support and the kind words about all we do at H4C! We are thankful to have your friend in the family.

  3. Thank you for the informative articles. They are very much appreciated especially because I am not able to financially utilise available help. “Doing it myself” is possible, even if restricted, because of wonderful people who share information in books, blogs, videos etc. Our creator is wonderful and so are the people he uses to help others. We learn from those ahead of us and teach those behind. That way we stay together as we move forward in understanding, healing and growth. Thank you for the analogies which make learning so much more memorable. They are one of my favourite ways of presenting information too. Vivienne

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