What Causes Cancer?

By Leigh Erin Connealy
Published on February 2, 2018
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Learning about the causes of cancer can set the path for a better future regardless of being diagnosed or not.
Learning about the causes of cancer can set the path for a better future regardless of being diagnosed or not.
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The Cancer Revolution by Leigh Erin Connealy
The Cancer Revolution by Leigh Erin Connealy

According toThe Cancer Revolution (Da Capo Press, 2017) chemotherapy and radiation have their place in treatment, but in many cases, they are simply not enough, because cancer isn’t caused by one thing, but by many different factors. All of these causes must be addressed, not just the tumor. The Cancer Revolution will equip you to make impactful, achievable lifestyle choices that fight the root of the disease, and that offer hope for recovery and a cancer-free life.

Identifying the exact cause of cancer has proven tricky for scientists. After all, if we knew the cause, we’d be closer to finding a cure. However, a wealth of scientific research suggests a specific set of risk factors for the disease.

Today, practically everyone knows that smoking cigarettes is linked to an increased risk of developing lung cancer, but how many know that there are more than thirty different factors that can lead to cancer? They can be grouped into three basic categories: infections (bugs), toxins, and biological factors. All of these things may cause cancer by disrupting the body’s homeostasis, research suggests. One way they do this is by creating oxidative stress and inflammation. Inflammation and free radicals damage the RNA and DNA (the genetic material) inside the cells, and with that, the cells’ mitochondria, or energy-producing furnaces.

When the mitochondria are damaged and a cell can no longer efficiently produce energy for itself, it reverts to an inefficient method of energy production called glycolysis, in which it depends on sugar as a fuel source. In this state, the organs and body systems can no longer work properly. This leads to more DNA damage, less energy for normal cells, and more fuel for cancer cells.

Environmental Toxins

Environmental toxins are one of the biggest causes of DNA damage and cellular mutations. The following is a list of some toxins that research links to cancer. I have divided them into two categories. The first describes toxins you are probably aware of and which you may already know can cause cancer. The second describes toxins that you may have heard of, but which you may not know are associated with cancer. In Chapter 5, I will share with you how you can help eliminate these toxins from your body and environment.

The “Usual” Suspects

  • Tobacco and smoking
  • Mercury toxicity—This comes from contaminated fish, water, air, and amalgam dental fillings (among other sources).
  • Sunlight—The shortwave rays of the sun cause reddening and sunburn and damage the superficial epidermal layers of the skin.
  • Other Toxins
  • Electromagnetic fields—Excessive exposure to electromagnetic fields (from microwave towers, cell phones, Wi-Fi, etc.) can cause cellular mutations that may lead to cancer.
  • Geopathic stress—This comes from energies with the Earth that are created by underground cavitations, streams, and other geological features. Such energies are harmful to the body.
  • Food additives—These are substances added to food to preserve its flavor or enhance its taste and appearance. They include things such as stabilizers, food coloring, dyes, and artificial sweeteners.
  • Foci infections, especially dental infections—Many of us have hidden foci infections in the body, which are concentrated and localized pockets of infection that don’t show up on routine lab tests. Among the most insidious and damaging of these are infections that are found in the mouth, and which are produced by root canals and jawbone infections. These infections produce toxins that could lead to inflammation and cancer.
  • Immunosuppressives and other drugs
  • Industrial toxins—These are ubiquitous in our air, food, and water supply. Industrial toxins, such as ammonia, fluoride, and chlorine, can be found in recycled water/tap water. For a list of all the common environmental toxins, go to the United States Department of Labor website: https://www.osha.gov/SLTC/emergencypreparedness/guides/chemical.html.
  • Ionizing radiation—This comes from such tests as X-rays and CT scans. Radiation can increase an individual’s cancer risk.
  • Irradiated food—Some of our food supply, especially spices, fruits, and meat, is irradiated to eliminate organisms that cause foodborne illness and to preserve the shelf life of food. This radiation damages the body. Although irradiated foods are common and found almost everywhere, there are clear ways to avoid them, such as buying produce from farmers’ markets, asking whether your produce contain GMOs, and growing your own fruits and vegetables.
  • Nuclear radiation—This comes from power plant accidents, such as what happened at the Fukushima power plant in 2011 in Japan.
  • Pesticides—These are sprayed on fruits and vegetables to keep pathogens from destroying them.
  • Polluted water—Tap water may contain such things as chlorine, fluorine, pharmaceutical drugs, parasites and other microbes, and other chemicals linked to cancer.
  • “Sick building” syndrome—This is caused by buildings that are contaminated by mold and other biotoxins.
  • Xenoestrogens—These come from plastics and other chemical compounds that mimic the effects of human estrogen upon the body.

As you can see, there are many more environmental toxins and factors that are linked to cancer than what you may have been aware of!

Infections: Viruses, Bacteria, Parasites, and Fungi

Viruses, bacteria, parasites, and fungi, such as molds, mildews, and Candida, cause inflammation in the body and can increase cancer risk.

Certain infections have also been directly linked to specific types of cancer. For instance, the human papilloma virus (HPV) has been associated with head and neck cancers, as well as cervical cancer. Epstein-Barr virus (EBV) is associated with leukemia. Hepatitis C has been linked to liver cancer, and colitis is related to colon cancer. Herpes II increases cancer risk in general.

You may not always know whether you have an infection in your body that’s creating an environment that is favorable to the development of cancer. A good integrative doctor can help you identify and eliminate any low-grade or underlying acute and chronic infections. Treating infections can help lower your risk of any cancers that may be directly caused by those infections. 

Biological Factors

Other factors that may cause cancer include:

  • A poor diet and nutritional deficiencies—Much of our soil is nutrient-depleted and loaded with pesticides and other toxins, as are some of the foods that line our supermarket shelves. Also, many people don’t consume whole foods and instead opt for processed, unhealthy, nutrient-depleted food.
  • Toxic emotions and chronic stress—We describe stress and emotions in greater detail later in this book. Experimental studies have shown that stress can affect a tumor’s ability to grow and spread.
  • Depressed thyroid function—This can result from gluten allergies, heavy metal toxins, radiation exposure, fluoride consumption, iodine deficiencies, and autoimmune disease, among other factors.
  • Intestinal toxicity—Many of us have an unhealthy gastrointestinal tract due to infections or because we eat harmful foods. Antibiotics, pesticides, and other environmental contaminants, as well as pathogenic infections and other factors, damage beneficial bacteria and the mucosa of the stomach and intestines.
  • Unbalanced “cellular terrain”—The internal terrain of your body determines how well every cell is oxygenated and nourished. Pathogens grow in the body when its internal terrain is out of balance. Nutritional imbalances, toxins, and acidic waste also contribute to an unhealthy terrain.
  • Hormone therapies—Birth control pills, synthetic estrogen hormone replacement therapy, and hormone blockers disrupt the body’s hormones and cause biochemical imbalances that may lead to cancer. RBSt, a synthetic hormone given to cows to accelerate their growth and that is found in conventionally processed meat and dairy products, can also cause imbalances.
  • Compromised detoxification—Your body’s ability to remove toxins can be compromised by bad circulation, scars, and other factors.
  • Cellular oxygen deficiency—This is caused by excessive acidity in the body, as well as by a lack of exercise, pollution, and/or a lack of carbon dioxide in the cells.

According to American Medical Research LLC (AMR), a medical research company, toxins are responsible for 70 to 75 percent of all cancers. Viruses and other infections cause 20 to 25 percent of all cancers, and electromagnetic pollution and genetics are thought to cause less than 5 percent each of all cancers.

Otto Warburg, a Nobel Prize winner, German physician, and physiologist, discovered that cancer occurs when any cell is denied 60 percent of its oxygen. Poor oxygenation results from a buildup of carcinogens and other toxins inside of and around the cells, which then damages the cell’s ability to utilize oxygen. Additionally, psychological and emotional stress and nutritional imbalances are important contributing factors to cancer, although researchers aren’t sure to what degree they play a role in its development. In The Cancer Revolution, I will show you how you can remove the effects of all of these factors from your body, so that you can either continue to live a cancer-free life, or help fight a cancer you may already have.

Finally, the following are some additional facts about cancer that you may not know:

  • Some studies link sugar to the growth of cancer cells. Sugar may increase the risk of certain types of cancer.
  • A sedentary lifestyle creates a lack of oxygen in the body and can contribute to cancer growth.
  • Bacteria, viruses, toxins, parasites, and heavy metals may indirectly increase cancer growth by suppressing the immune system.

You are more likely to get cancer if your immune system is already compromised. According to the Canadian Cancer Society, a compromised immune system increases an individual’s chances of contracting different viruses and bacteria that can increase the risk of cancer. 

How Tumors Are Formed

Every cell has the capacity to become a cancer cell under the right conditions. When a normal cell becomes damaged and mutates, it ceases to work as part of the team and community of other cells that it is a part of, and instead starts to work for itself, for its own survival. As part of this process, it grows rapidly and doesn’t respond to the body’s natural cellular control mechanisms.

So, tumors start with a normal cell mutating into an “immortal,” uncooperative cancer cell. This cell then multiplies and proliferates until it becomes a mass of cells. Once this mass reaches a certain level, it seeks to form a “nest” somewhere in the body, and by this means it begins to establish itself in a specific organ or set of tissues to become what we know as a tumor.

As the tumor grows larger, it begins to require greater and greater amounts of nutrients from the blood, until it finally creates its own set of blood vessels and blood supply in a process called angiogenesis. Finally, if left unchecked, some of the cancer cells will break off from the tumor and establish new tumors, or “nests,” in other parts of the body (metastasis).

Normally, your immune system will detect and destroy any cancer cells before they are able to form a colony of cells or a tumor. But if your immune system is compromised by toxins or infections, and is “blinded” by inflammation, cancer cells can more easily reproduce. As the cancer cells reproduce, they coat themselves with a substance called fibrin, which helps them hide from the immune system and stick together and form a colony. That colony will then attach to a wall in your smooth muscle and begin developing blood vessels so that it can get more nutrients from your blood to feed itself.

To further enable its survival, the newly developed tumor will send out a lot of other information, in signals known as growth factors, to the rest of the body that will aid in its growth and development. There are many different signals that tumors put out, so it’s important to prevent or halt these transmissions. Cancer has multiple survival strategies, all of which need to be addressed with different treatments, at the same time that your body must be repaired and restored from the “earthquake.”

Can We Prevent Cancer?

Although many factors in our environment cause cancer, and cancer has multiple survival mechanisms to help it grow in the body, most of the time we can prevent it! According to a recent Japanese study, we all have 75 million cancer cells in our body at any given time. Normally, our immune system keeps these cells in check, but when the immune system becomes compromised over a long period of time, these cells can begin to proliferate, or multiply. But we can help stop this process by consuming a nutritious diet.

It takes ten to twelve years on average for a single cancer cell to eventually multiply to where it becomes a full-grown tumor in the body. This means you often have a lot of time to eliminate the things that are causing cancer, if you catch it in the early stages. There are early-detection tests that you can do, such as the Cancer Profile, which I describe in greater detail in Chapter 2. This test, among others, aims to help determine whether the environment in your body is favorable to the development of cancer, or whether cancer is already “brewing or fermenting” somewhere in it, many years before it actually becomes a disease.

Currently, not many doctors in the United States know how to prevent cancer because most are trained to be reactive with their patients instead of proactive. The good news is that increasingly, doctors are being trained in functional and integrative medicine and are helping their patients help prevent cancer, just as we do at our clinic. Cancer is a global illness, affecting the entire body; it’s not just a disease of a single body part, so it’s essential that you work with a doctor who can look at your entire body and tell you whether you have an internal environment that is favorable to its development. In Chapter 10 and the Resources section at the end of this book, I provide a list of referral organizations and tips that will help you find such a doctor.

To prevent or fight cancer, you must also resolve the stress and emotional conflicts in your life. I describe both of these factors in greater detail in Chapter 8. I often ask my patients whether they want to be well, and tell them, “I can’t help you until you get your mind in order.” You must want to be well and discipline yourself to do all the right things if you want to heal.

It’s like weight loss. Unfortunately, according to the United Institute of Health and Human Services, about two thirds (68.8%) of the population is characterized as being overweight. Some are overweight because they don’t “pay attention to their intention” (their mind and thoughts). Everyone wants to pop a pill for every ill, but we have known for a long time that this doesn’t work. So, why are we still looking to “pop a pill,” when we know that doesn’t work?

I sometimes tell our patients, “Do you know that very talented artists, musicians, and performers such as the most famous pianists in the world, even though they were born gifted, still have to practice the piano for five hours a day? Or, take famous basketball players, such as Kobe Bryant: Although he was born with the necessary height and talent to succeed in basketball, he still has to practice playing the sport daily. So it is with your health. You have to practice at being healthy because health is a process, not a one-time event. You don’t just become healthy one day.”

My daughter once said to me, “Mom, you are just so disciplined about the way you live.” And I told her, “I have worked at my health my entire life, because I’ve faced great adversity. If I don’t work at my health and if I’m not disciplined, then I pay for it. And I don’t want to pay. I’d rather be disciplined and have a good outcome.”

Another analogy I give my patients has to do with driving. I will say to them, “Do you drive? If you do, then you know that there is a rulebook for driving, and that you have to know the rules and laws of driving a car.” Then I will ask them, “How many stop signs did you run today? None, right? Because you know that you’d probably get a ticket, hurt somebody, or crash the car if you did.

“Similarly, you have to pay attention to the rules of your body. Because nobody wants to get into a car accident, and I don’t want you to have a body accident! If you follow the rules and laws of Mother Nature, then the right things will happen in your body.”

It’s not about perfection, though, because none of us are perfect drivers, and you aren’t going to be a perfect driver with your health. But you want to follow the rules of nature so that your body works for you, not against you. What percentage of the time do you think you can get away with running a stop sign? Once in a while, right? But that’s about it.

Preventing cancer doesn’t need to be complicated. You just need to learn a few key things about how to be well, which you can do without spending a fortune. Likewise, if you have already been diagnosed with cancer, there are many simple lifestyle and dietary changes that you can make that can help you battle the disease and live a longer, more vibrant life, which you will find throughout this book.


Adapted from The Cancer Revolution: A Groundbreaking Program to Reverse and Prevent Cancer by Leigh Erin Connealy, MD. Copyright ©2017. Available from Da Capo Lifelong Books, an imprint of Perseus Books, LLC, a subsidiary of Hachette Book Group, Inc. 

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