Why Cancer of the Heart is So Rare

To understand why cancer in the heart is extremely rare, we must first understand what cancer is. Cancer is a metabolic disease, which means that it occurs when there is a breakdown in normal metabolism that in turn causes shifts in the cell that result in it becoming cancerous. Way back in the 1920’s Otto Warburg and his team discovered that cancer cells stopped relying on what is called oxidative phosphorylation, the main way our cells make energy, and instead relied on what is called glycolysis and lactate fermentation.(r) This is called the Warburg Effect. It basically means that instead of using oxygen to make energy the cells found a way, or were forced to find a way, to make energy without having to use oxygen.

More recently, metabolic researcher Dominic D’Agostino and cancer researcher Dr. Thomas Seyfried have solidified the metabolic theory of cancer. (r,r) Let’s get a better understanding before we move on to the heart. If we look at cancer cells, they have some interesting characteristics. They are anaerobic, meaning they don’t use oxygen, they are acidic, they are rapidly dividing, and they are undifferentiated, meaning they are no particular type of cell but just a general cell. (r) So, we have cancer cells that display this Warburg Effect and have these unique characteristics. But why would the cell decide to have these characteristics and become cancerous? Let’s illustrate this another way.

When a human in conceived the egg and sperm come together to form a zygote cell. That cell implants itself on the side of the uterus. At this point, the cell has no blood supply and therefore no oxygen. Initially this cell grows into what is called a Morula, and then a blastocyst, by rapidly dividing to start the process of growing a fetus. Interestingly, these early dividing cells are anaerobic, (r) undifferentiated, and rapidly dividing. Sounds like cancer. Once the blood supply from the placenta develops at around the 2-week mark, the cells of the fetus start to use oxygen and become aerobic, they start to differentiate into different types of cells, and they have more controlled cell division. The key here is the presence of oxygen.

The question when it comes to cancer is why a cell stops using oxygen and become cancerous. Well, the structures in our cells that allow our cells to use oxygen to break the chemical bonds in our food to make energy for our bodies are called our mitochondria. These structures are very good at oxidative phosphorylation, provided they do not become damaged. Every time our mitochondria make energy we also make a waste product called a free radical, kind of like a car makes and exhaust when burning fuel. These free radicals can be damaging to our bodies if not taken care of. Normally, our bodies make what are called antioxidants that immediately take care of these free radicals.

However, if we are not careful how we live our lives then we can end up creating an abundance of these free radicals that can overwhelm the cells. Excess free radicals can be caused by toxin exposure, (r) relying on carbs for fuel, (r) inflammation, and high blood sugar. (r) When this happens, it can cause damage to the mitochondria. (r) Since the mitochondria are what allow us to us oxygen to make fuel now the cell cannot use oxygen anymore. If it can’t do this, it can’t survive. This triggers the cell to turn on oncogenes in the DNA of the cell that instruct the cell to become anaerobic, undifferentiated, and rapidly dividing cancer cells, the only thing it knows how to do to survive. When faced with the situation of not being able to use oxygen the cells must either die or become cancerous. It’s sort of a survival mechanism. The cancer solution keeps the tissue alive short-term, but it is obviously not a good long-term solution.

So, as I mentioned there are many thing that can cause excess free radicals in our bodies that damage our mitochondria. One is the large amount of toxins our bodies are exposed to on a daily basis. Everything from heavy metals, to plastics, to artificial fragrances. According to Herbert Needleman, who spent his life studying the effect of chemicals on children, at least 70,000 new chemical compounds have been invented and dispersed into our environment since 1950, and many of them can act as free radicals directly. But even worse than toxins, free radicals can increase dramatically when our cells become too reliant on burning carbohydrates for fuel instead of fatty acids and ketones. (r,r) This is where everything starts to relate to the heart.

The cardiac myocytes are the most mitochondrial dense cells in the body, (r) this is because of the massive amount on energy the heart needs and the large amount of oxygen it uses. Most of our organs prefer to burn fat for fuel, but especially the heart. (r) When other organs are forced to burn predominantly glucose for long periods of time then the sequence of events described above can start to happen and result in cancer. However, as I discussed in another blog post, if the heart is forced to burn predominantly glucose then something far worse and potentially fatal can happen, a heart attack.

Because of this, the body has built in mechanisms that make sure the heart is never forced to burn predominantly glucose for fuel. One is the direct delivery of the fatty acid carrying chylomicrons from digestion through the lymphatic system to the veins that drain into the heart. (r) Secondly, the heart has a direct signaling pathway to fat cells (r) that I believe allows it to mobilize fats when glucose burning becomes to prevalent. Unfortunately, there is a situation where the heart could still be forced to burn predominantly glucose. It has to do with an imbalanced stress response signal to the heart cells.

The control of the balance of the autonomic nervous system in cardiac cells, and many other cells, relies on two messenger molecules called cAMP and cGMP. cAMP levels rise in the heart cells when we have a stress response and cGMP levels rise when we are in a relaxation state. The only difference is that when it comes to cGMP, the relax molecule, something else is also needed to increase its levels. That something else is nitric oxide, NO, which is produced in the walls of arteries. These two molecules—cAMP and cGMP—keep each other in check within heart cells, they should always balance each other out. When we experience a stressful response and the nervous system causes spikes in cAMP within the heart then cGMP, provided there is enough NO, also has an increase just to keep the system more in balance.(r) This is depicted in the image below.

Sroka, K. (2013). What is the connection between oxidative stress and heart attacks? Retrieved from heartattacknew.com/faq/what-is-the-connection-between-oxidative-stress-and-heart-attacks/