Oxidative Stress: How Asthma, COPD, Oxygen May Increase Lung Cancer Risk

There is some evidence linking supplemental oxygen with certain cancers. So, is it true that supplemental oxygen may cause cancer? Why might this happen? Let's investigate the evidence.

In 2002, we wrote how high concentrations of oxygen were linked with cancer. That article noted that inhalation of an FiO2 of 100% for three hours increased the risk for developing cancer later in life. The reason was due to oxidative stress.

In a future post I want to investigate oxidative stress. What exactly does this do to the body? What causes it? What does it actually involve? How might it lead to cancer? So, that's a future investigation we will undertake.

For now, all you need to know is that oxygen, once it gets inside your body, splits into unpaired electrons. When a molecule has an unpaired electrons it is said to be unstable. It is referred to as a free radical. Free radicals will steal an electron from other molecules.

Under ideal circumstances, it steals an electron from an antioxidant. These are substances inside our body's meant to neutralize free radicals by donating an electron. Antioxidants can be ingested by eating certain foods, such as those containing vitamin C and E.

Sometimes, however, your body becomes overwhelmed with free radicals. There are certain disease processes that can cause this. Certain drugs can cause this, and one example is supplemental oxygen. In this case, your body becomes so overwhelmed with free radicals that they overwhelm antioxidants.

In excess, free radicals steal electrons from cells. So the cell now becomes unstable. It then it in turn steals an electron from a nearby cell. This creates a chain reaction of sorts. And this is what is referred to as oxidative stress. Cells become stressed. When this happens they release a substance called Reactive Oxygen Species (ROS). This triggers an immune response.

And, when this happens, they release chemicals such as cytokines and chemokines. These are your proinflammatory chemicals. They warn your immune system that something is wrong. And your immune cells release more cytokines and chemokines. These chemicals are helpful when you are exposed to bacteria and viruses. But, in excess, they can also be damaging to cells.

Other things that can cauuse oxidative stress like this are exposure to allergens and exposure to toxic chemicals in cigarette and wood smoke. This may explain how airways of asthmatics and COPD patients become chronically inflamed. So, it can explain many disease processes. And this includes cancers.

Oxidative stress may cause chronic inflammation. This may be what causes inflammatory diseases, such as asthma, COPD, diabetes, cardiovascular disease, and neurological diseases. And, as noted, it may also explain the links between some of these diseases and various cancers.

Under prolonged stress like this, oxidative stress is prolonged. So you end up with lots of ROS and similar substances roaming around. They can also cause gene mutations. Some of these mutations may cause the gene to produce harmful substances that may begin the cancer process.

This may explain the link between COPD and lung cancer. It actually might explain links between asthma and lung cancer. Studies show asthmatics are 2-6 times more likely to develop lung cancer than non-asthmatics. So, this may explain this link.

This is all very complex. There are very long and almost inexplicable articles on this stuff. But, my goal is to make it easy to understand. So, just keep in mind there is a lot more involved here than what I explain.

So, this may explain how long-term oxygen therapy, while relatively safe, is not without potential long-term side effects. It may also explain how those high doses of oxygen, even for short terms, may cause cancers later in life.
References.

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8. Nele, Cielen, Karen Maes, Ghislaine Gayen-Ramirez, "Musculoskeletal Disorders in Chronic Obstructive Pulmonary Disease," Biomed Research International, 2014, https://www.hindawi.com/journals/bmri/2014/965764/, 5/31/17
9. Eldridge, Lynne, "Does Asthma Increase The Risk Of Lung Cancer?" verywell health, 2017, June 19, https://www.verywellhealth.com/does-asthma-raise-the-risk-of-lung-cancer-2248983, accessed 8/19/19
10. Reuter, et al., "Oxidative stress, inflammation, cancer: How are they linked?" Free Radical Biology & Medicine, 2011, December 1, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2990475/, accessed 8/19/19