Prathima Cancer Institute

Lung Cancer Causes

Lung Cancer Causes


For centuries, smoking has been a widespread habit that continues to be a major public health concern despite extensive public health campaigns and warnings about its hazards. It stands as a primary cause of preventable diseases on a global scale. According to the Best Oncologist in Warangal, among the various health risks linked to smoking, its association with lung cancer is particularly notorious. Here we aim to explore the detrimental effects of smoking on the respiratory system, how lung cancer develops, and the crucial importance of quitting this deadly habit on World Lung Cancer Day.

The Anatomy of the Respiratory System:

Before delving into the connection between smoking and lung cancer, it is essential to understand the anatomy of the respiratory system. The lungs, two spongy organs located in the chest, are crucial for the exchange of oxygen and carbon dioxide during the breathing process. Oxygen is taken in through the airways, which consist of the trachea, bronchi, and bronchioles, and reaches the air sacs known as alveoli. Here, the oxygen is absorbed into the bloodstream, while carbon dioxide is expelled during exhalation.

How Smoking Affects the Respiratory System:

Tobacco smoke comprises a myriad of detrimental components, consisting of carcinogens and toxic substances, totalling thousands in number. When inhaled, these harmful components enter the lungs and wreak havoc on the respiratory system. Smoking has several detrimental effects on the lungs:

1. Irritation and Inflammation: The chemicals in tobacco smoke irritate the lining of the airways, causing inflammation and excessive mucus production. This reaction can lead to chronic bronchitis, characterized by persistent coughing and difficulty breathing.

2. Damage to Cilia: The respiratory system relies on tiny hair-like structures called cilia to sweep away mucus and debris. Smoking damages these cilia, impairing their ability to clear the airways, which increases the risk of infections.

3. Destruction of Lung Tissue: As per the Best Cancer Hospital in Warangal, smoking causes damage to the alveoli, leading to a condition called emphysema. Emphysema results in the loss of lung elasticity, making it increasingly difficult for the lungs to expand and contract during breathing.

4. Reduced Lung Function: Over time, smoking can decrease lung function, leading to a condition known as chronic obstructive pulmonary disease (COPD). Characterized by progressive and debilitating effects, COPD is a lung disease that severely hampers breathing.

The Link Between Smoking and Lung Cancer:

Lung cancer is a malignant tumour that originates in the lungs and can quickly spread to other parts of the body. The vast majority of lung cancer cases are directly linked to smoking, making it one of the most preventable forms of cancer. Several mechanisms explain the connection between smoking and lung cancer:

Carcinogens in Tobacco Smoke:

Tobacco smoke contains more than 7,000 chemicals, and at least 69 of them are known to be carcinogenic (cancer-causing) to humans. These carcinogens include polycyclic aromatic hydrocarbons (PAHs), benzene, formaldehyde, nitrosamines, and heavy metals like arsenic and cadmium. When smokers inhale tobacco smoke, these carcinogens enter their lungs, where they can directly damage the DNA in lung cells.

DNA Damage:

The genetic material within our cells, DNA, controls cell growth and division. Carcinogens in tobacco smoke can cause mutations in the DNA of lung cells, disrupting the normal cellular processes that regulate growth and repair. In some cases, these mutations may lead to the uncontrolled growth of cells, forming tumours in the lungs. This uncontrolled cell growth is the hallmark of cancer.

Activation of Oncogenes:

Oncogenes are genes that, when mutated or activated, can promote cell growth and division. Carcinogens in tobacco smoke can activate these oncogenes, leading to the abnormal proliferation of lung cells. For example, mutations in the KRAS oncogene are commonly found in lung cancer, and smoking has been linked to an increased frequency of KRAS mutations.

Inhibition of Tumor Suppressor Genes:

Tumour suppressor genes are responsible for regulating cell division and preventing the development of cancer. When these genes are functioning correctly, they can repair damaged DNA or trigger cell death (apoptosis) in abnormal cells. However, tobacco smoke can interfere with the normal function of tumour suppressor genes, reducing their ability to suppress cancer development.

Oxidative Stress:

Tobacco smoke contains free radicals, which are highly reactive molecules that can cause damage to cells, including lung cells. When the body’s antioxidant defense’s are overwhelmed by the free radicals present in tobacco smoke, it leads to oxidative stress. Chronic oxidative stress in the lungs can contribute to the development of cancer by promoting DNA damage and cellular dysfunction.

Chronic Inflammation:

Smoking triggers chronic inflammation in the lungs, as the body attempts to repair the damage caused by tobacco smoke. Prolonged inflammation can create an environment that promotes tumour growth and progression. It also hampers the immune system’s ability to recognize and eliminate cancerous cells, further increasing the risk of cancer development.

Synergistic Effects:

The risk of developing lung cancer is not only related to the number of cigarettes smoked but also the duration of smoking as said by the Best Oncologist in Warangal. Furthermore, there are synergistic effects between smoking and other risk factors, such as exposure to secondhand smoke or occupational hazards like asbestos. These factors can amplify the carcinogenic effects of smoking, significantly increasing the risk of lung cancer.

Role of Smoking Cessation:

The good news is that quitting smoking can substantially reduce the risk of lung cancer over time. Even if someone has smoked for many years, quitting at any age can lead to significant health benefits. Research indicates that the risk of lung cancer decreases with each year of smoking cessation, although it may never return to the baseline risk of a non-smoker.

Statistical Evidence:

The statistics surrounding smoking and lung cancer are staggering and illustrate the severity of the issue:

1. World wide tobacco use is responsible for approximately 90% of lung cancer cases worldwide.

2. Worldwide over 1 million people die due to lung cancer each year.

3. Lung cancer is the leading cause of cancer-related deaths globally, with a five-year survival rate of only about 15%.

4. Each year, more people die from lung cancer than from breast, colon, and prostate cancers combined.

5. The risk of developing lung cancer is closely linked to both daily cigarette consumption and the duration of smoking. However, the risk diminishes significantly over time after quitting smoking.

The Importance of Quitting Smoking:

Despite the dire statistics, there is hope for smokers and those exposed to secondhand smoke. Quitting smoking, even after years of tobacco use, can significantly reduce the risk of developing lung cancer and other smoking-related diseases. Here are some considerable facts to believe:

1. Immediate Benefits: The human body is remarkably resilient, and quitting smoking leads to immediate health benefits. Within hours, carbon monoxide levels in the blood decrease, allowing more oxygen to reach vital organs. Within days, the sense of taste and smell improves, and within weeks, lung function starts to improve.

the greater the reduction in the risk of developing lung cancer and other smoking-related diseases. Even those with a history of heavy smoking can significantly reduce their risk over time.

3. Support and Resources: Quitting smoking can be challenging, and many individuals benefit from support systems such as counselling, nicotine replacement therapies, and support groups. Governments and healthcare organizations often provide resources to assist individuals in their journey towards becoming smoke-free.

4. Impact on Others: Quitting smoking not only improves the health of the individual but also protects those around them from the harmful effects of secondhand smoke. Creating a smoke-free environment benefits everyone’s health.


The link between smoking and lung cancer is undeniable and well-established. The harmful chemicals in tobacco smoke directly damage the respiratory system, leading to chronic diseases like COPD and, ultimately, lung cancer. However, quitting smoking can significantly reduce the risk of developing lung cancer and offers a chance for improved health and well-being. Let’s make World Lung Cancer Day a day for raising awareness about the dangers of smoking, promoting smoking cessation programs, and implementing effective public health policies. By working together to combat smoking, we can make significant progress in preventing lung cancer and improving public health globally.







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