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Lung cancer is distressingly common. Worldwide, over 2 million people per year are diagnosed with lung cancer, including over 200,000 in the USA. It is more common in men than women. Lung cancer has many debilitating symptoms, including chest pain, voice changes, weight loss, discomfort, coughing blood, and death. Lung cancer is the highest cause of cancer death in men and the second highest in women, and the outlook gets worse the later in the disease you are diagnosed. So what causes lung cancer, how does it work, and is there anything we can do about it?

Lung cancer has several different risk factors, including low socioeconomic status, HIV, and some lung diseases. According to the National Institute of Health, radiation from atomic bombs can also increase your risk, so avoid atomic bombs. None of these come even close to the explosive risk from smoking, however. Smoking causes lung cancer and increases your risk of developing lung cancer by 20 times versus people who have never smoked. Smoke contains a lot of chemicals. Some of these enter the cells that line the throat and lungs and damage the DNA. Unfortunately, the advent of filtered cigarettes encouraged people to inhale smoke more deeply and increased cancer rates. There are at least 15 genes implicated in the conversion of cells from normal to cancerous. Cigarette smoke, along with air pollution, other carcinogens, and random mutation, can change some of the DNA in these genes and make cells cancerous.

Let’s take a quick second to review what cancer is. Cancer cells are cells that have mutated and act more like independent, single-celled organisms than part of your body. They grow and divide even when they aren’t supposed to, they don’t kill themselves when they outlive their usefulness, and they move around invading other parts of the body. Unlike most single-celled organisms, they are extremely difficult to kill. They are made out of our cells, so most medicines can’t distinguish them, they hide from the immune system, and they convince parts of the body to aid their unrestricted growth. Each of these is an individually unlikely mutation. Still, the damaging effects of carcinogens like cigarette smoke cause many rapid changes in the genes of the cell, increasing the possibility that cells will acquire the necessary mutations. As cells reproduce out of control, they are more likely to mutate and acquire the other necessary mutations to become cancerous. They act independently and take resources, space, and blood from healthy cells, crowding them out and destroying large body systems.

Lung cancer is differentiated from other cancers in an obvious way; the cancerous cells originate in the lungs. Epithelial cells line the lungs and create a protective barrier against environmental hazards. When they are exposed to smoke and other carcinogens this can cause mutations. Medical professionals and researchers have long-differentiated subtypes of lung cancer based on the type of cell that has become cancerous. These are broadly defined as small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC). SCLC is very aggressive. It makes up 15% of all cases and has a 5-year survival rate under 10%. This type of lung cancer responds well to chemotherapy but spreads rapidly and is difficult to treat when it has moved extensively. NSCLC makes up the rest of the cases, 85%. There are several subtypes, including squamous cell and large cell carcinoma and adenocarcinoma, the most common type. NSCLC has a multi-step process and can be caught early when cells are replicating or grouping together but are not yet cancerous. This type of lung cancer does not respond as well to chemotherapy. Surgery or surgery combined with chemotherapy is usually recommended.

So what can we do about lung cancer? First and foremost, if you don’t already have lung cancer, make sure you STOP SMOKING. There are programs, medications, and support groups that may help. Non-smokers should also be aware of the risks and symptoms. Beyond that, early detection is critical. Cancer can be localized in only one organ, spread to the lymph nodes, and eventually spread throughout the body. When lung cancer is localized, 5-year survival rates are over 50%. When it has metastasized and spread to other locations, that survival rate drops below 5%. If you are at risk, inquire with your doctor about lung cancer screenings and be vigilant. If you currently have lung cancer, your doctor has the best information available for your specific case. Treatments include surgery and chemotherapy, along with radiation therapy, immunotherapy, laser therapy, stents, and experimental treatments. Though ENCORE Research Group sites do not currently have any lung cancer trials enrolling, we know this is a critical matter for many people. Follow this link for lung cancer clinical trials that may be in your area:  clinicaltrials.gov/ct2/results?cond=lung+cancer.

Staff Writer / Editor Benton Lowey-Ball, BS, BFA

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References:

Schabath, M. B., & Cote, M. L. (2019). Cancer progress and priorities: lung cancer. Cancer epidemiology, biomarkers & prevention, 28(10), 1563-1579. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6777859/ 

NIH National Cancer Institute Non-Small Cell Lung Cancer Treatment (February 17, 2023) https://www.cancer.gov/types/lung/hp/non-small-cell-lung-treatment-pdq

NIH National Cancer Institute Small Cell Lung Cancer Treatment (March 2, 2023) https://www.cancer.gov/types/lung/hp/small-cell-lung-treatment-pdq

NIH National Cancer Institute What is Cancer? (October 11, 2021) https://www.cancer.gov/about-cancer/understanding/what-is-cancer