Pathophysiology of Lung Cancer

Lung cancer is a disease affected by many factors, including biological ones. It is currently the leading cause of cancer death across the world. It is often an illness with intense symptoms and poor long-term outlook.^1,2

Understanding lung cancer means looking into its pathophysiology. This is the study of changes in the body that occur along with lung cancer. The main pathophysiological factors linked to lung tumor development are:^2-7

• Pain
• Chronic obstructive pulmonary disease (COPD)
• Inflammation
• Aging

Many processes can lead to lung cancer. And there are many types of lung cancer, such as small-cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Depending on the pathophysiology, these processes and types of lung cancer can appear differently for each person.^1,2

Pain

Pain is a common cancer symptom. Overall, almost half of people with lung cancer have pain. It can deeply lower someone’s quality of life. Those with lung cancer who have moderate to severe pain tend to be younger. Interestingly, older patients are much less likely to report pain with cancer.²

Pain management in cancer treatment often involves palliative care. This is specialized care offered to relieve pain and symptoms related to a deadly disease. Pain killers (analgesics) are the go-to treatment for cancer pain. Those who do not get pain relief from analgesics may be able to receive nontraditional pain management treatments.²

COPD

COPD is a chronic, inflammatory disease of the lungs. It is strongly linked to both smoking and lung cancer. Cigarette smoke causes inflammation in the airways and lungs. This eventually leads to destruction of alveoli. Alveoli are tiny sacs in the lungs that allow oxygen and carbon dioxide to be exchanged. Alveolar damage plays a key role in COPD.^3-5

People with COPD are both more at risk for getting lung cancer and more prone to poor outcomes from it, even after treatment. COPD and lung cancer are closely related. They share a lot of the same risks and abnormal lung processes. This makes having lung cancer with COPD harder to treat.⁵

Inflammation

Chronic inflammation is known to play a big role in tumor development. Immune problems like inflammation can reduce the body’s ability to fight diseases or recognize abnormal cells like cancer. Cancer often develops at sites of chronic inflammation.^5,6

Many cancers occur during chronic activation of the immune system. In particular, lung cancer and inflammation happen in a vicious cycle. Inflammation of the lungs is a risk factor for both lung cancer and COPD.^5,6

Aging

The aging of cells as people get older causes many changes in the body. Some of these changes are visible. But many changes happen on a molecular level. These changes can lead to increased risk of disease and death. Aging cells can react more poorly to cellular stress, like disease or inflammation.⁷

Lung function in aging people can get worse over time. Most lungs undergo physical changes with age that make it harder to exchange oxygen for carbon dioxide. This leads to decreased lung function.⁷

Aging also causes changes in the immune system that can increase the risk of infections. This may hurt the body’s defenses against diseases like cancer.⁷

What is the difference between SCLC and NSCLC?

SCLC is a rarer, more aggressive form of NSCLC. NSCLC makes up almost 90 percent of lung cancer diagnoses. NSCLC often progresses slowly with little to no symptoms until it gets to the advanced stages. Nearly half of NSCLC presents as end-stage (stage 4) lung cancer.⁸

Types of NSCLC include:⁸

• Lung adenocarcinoma
• Large-cell undifferentiated carcinoma
• Squamous cell carcinoma

SCLC usually begins in the bronchi of the lungs. Bronchi are airways that go from the windpipe (trachea) to the lungs. SCLC is fast growing and spreads to sites like the lymph nodes. It is usually caused by tobacco smoking and changes in 2 genes that typically offer protection against cancer. Types of SCLC include small-cell carcinoma and combined small-cell carcinoma.^1,8

Each person has different pathophysiology that affects their risk for lung cancer. If you are concerned about your lung cancer risk, talk to your doctor to determine the best path for you.