Lung Cancer


Cancer is the uncontrolled and undifferentiated mass of cells. When our body cells divide out of control and lose the property of contact inhibition, they keep on dividing and form a lump of tissue that doesn’t have an organized structure and is termed "cancer cells." Normal cells grow and divide by the process of cell division, and when they grow old and lose their property of continuous division, they die eventually, but cancer cells undergo continuous division, escaping the process of death.

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Lung cancer is a cancer of the lungs. When cells present in the lungs show abnormal cell growth and division, it is called lung cancer. It is the most common type of cancer and the leading cause of death in the world. Lung cancer generally starts from the cells that line the bronchi or alveoli. It can also spread to other parts of the body, such as the liver, blood, or lymph nodes, and can cause new cancer there. Lung cancer is more common in men as compared to women.

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There are generally two main types of lung cancers −

  • Non-small Cell Lung Cancer (NSCLC) - It is the most common type of lung cancer and is involved in 80-85% of total lung cancer cases. It grows and spreads to other parts more slowly as compared to the other types.

  • Small cell lung cancer (SCLC) - It comprises about 10-15% of all cases, but it has the capacity to grow and divide at a faster pace. Most of the time, cancer by the time it was diagnosed, it had already grown and spread to other body parts. 90% of cases were found in people who were active smokers.

Stages of Cancer

The stage of cancer is determined by two main factors −

  • Location and size of the tumor.

  • Whether it has undergone metastases or not.

Stages of NSCLC

Stage 0 - It is called the occult stage. Here the tumor is established, but it is not detected in imaging scans.

Stage 1 - Tumor size is very small and it is not spread to other parts or lymph nodes.

Stage 2 - Cancer size increases inside the lungs but it is not spread to the outer parts of the lungs. It can be removed surgically with additional treatments.

Stage 3 - Cancer may have spread to other parts or nearby lymph nodes. Stage 3 is often impossible to treat or can be followed with cancer removal by surgery, chemotherapy, or radiation therapy, followed by immunotherapy.

Stage 4 - It means that cancer has spread to other organs or body fluids. Once it enters the bloodstream, the chances of metastasis to other organs anywhere in the body increase. Lung cancer generally spreads to the brain, heart, or chest region.

Stages of SCLC

  • Limiting Stage - In this stage, the cancer hasn’t spread to the other lung or nearby lymph nodes; it is present in only one lung.

  • Extensive Stage - It means that the cancer has spread to both of the lungs, the fluid surrounding the lungs, and to other areas of the body as well.

Causes of Lung Cancer

  • Smoking - It is the leading cause of lung cancer around the globe. People who smoke are at a greater risk of developing cancer than non-smokers. Tobacco smoke contains many active carcinogens that can cause cancer. Smoking cigarettes is not the only cause. Having cannabis, or joints, is also known to cause more harm than cigarettes alone. As they need to be inhaled, they can hold the smoke for a longer duration in the lungs leading to cancer.

  • Passive smoking - Exposure to cigarette smoke or second-hand smoke can also increase the possibility of having cancer.

  • Radon - It is an inert, colorless and odorless radioactive gas found naturally in soil. It can come up through the soil and can seep or leak into the home and increases the chances of exposure and lung cancer risk.

  • Chemicals and Pollution - There are certain chemicals that are used in various occupations but are carcinogenic in nature. Exposure to this chemical or certain pollutants in the air or soil may increase the possibility of developing cancer at later stages of life. Examples

    • Arsenic

    • Asbestos

    • Uranium

    • Nickel

    • Coal and coal fumes

    • Silica

  • Genes - There is a small chance that cancer can be hereditary. If you have a family history of cancer that means that you are also at high risk of developing cancer.

Symptoms of Lung Cancer

Symptoms vary from person to person. In some, it can be related to the lungs only, but if it has metastasized to other body parts, the person can show symptoms related to that organ also. Common symptoms for lung cancer are −

  • Constant cough that gets worse with time

  • Chest pain or chest infection

  • Blood in cough

  • Shortness of breath

  • Loss of appetite

  • Constant tiredness

  • Lung infection

  • Difficulty or pain in swallowing (Dysphagia)

  • Swelling of the face, arm or neck

  • Jaundice

  • Hoarseness of voice

Diagnosis and Treatment of Lung Cancer

There are certain tests which doctors perform to confirm lung cancer, such as −

  • CT Scan - A detailed image of the lungs is taken using X-ray and before the test, a dye is injected into the patient to get more clear and more precise picture. It can detect small lesions or abnormal masses of cells that cannot be detected by X-ray.

  • PET-CT Scan - It is done if a CT scan shows a positive result for cancer and is done to detect the active cancer cells’ position in the body.

  • Sputum Cytology - In case a person is coughing with a lot of mucus, a sample of sputum can also be used to detect the presence of cancer cells.

  • Bronchoscopy - It is a type of biopsy, a tube with a camera at the end is inserted into your airways, either through your mouth or nose, and a sample of cells is taken to study under laboratory

The treatment for lung cancer will depend on several factors, such as the type of lung cancer, the size and position of the cancer cells, and how advanced the stage is.

  • Surgery - This is considered as the primary treatment for cancer, abnormal mass of the cell is detected by checking the health state of the individual and the mass of the cell is retracted out.

  • Chemotherapy - It is better for patients who have lung cancer over the age of 50 as there will be complications in surgery, so chemotherapy is conducted. Some Chemicals are injected into the body through veins to kill cancer cells. It is proven to be effective in curing all stages of lung cancer.

  • Radiation Therapy - In this high energy rays are used to kill the cancer cells and to reduce the symptoms. It can be used either as a primary treatment or after surgery or chemotherapy to kill any remaining cancer cells.

  • Targeted Therapy - In this specific molecules or proteins on the cancer cells are targeted and specific antibodies or monoclonal antibodies are designed and used on target cancer cells.


Lung cancer is the most common cause of death, and the primary reason is tobacco smoking. Most of the effected people are direct cigarette smokers and the rest are exposed to second-hand smoke which is the leading cause of lung cancer. Certain surgical procedures and therapies are used nowadays to reduce the cancer cell size, and treatment plans are also being used to minimize the chances of recurrence of cancer.


Q1. What are carcinogens?

Ans. Carcinogens are any chemical or any agent that is capable of causing some mutation in genes that can lead to cancer. It can be natural, such as UV rays, or can be man-made such as cigarette smoke.

Q2. What is “metastasis''?

Ans. "Metastasis” is the spread of cancer cells from the organ where they have started to some other organ or bloodstream. Some cells lose from the cell lump and reach the bloodstream, from there they have the capability to reach any part of the body and start a new tumor there.

Q3. Explain PET Scan?

Ans. PET stands for Positron Emission Tomography. It is an imaging test that uses radioactive substances to look for cancer in the lung. It is used along with the CT scan, CT scan detects the presence of abnormal cell mass, and the PET scan detects the activity of these cells.

Q4. What is advanced stage lung cancer?

Ans. Advanced stage lung cancer is a stage 4 cancer. It is also called "metastasized cancer," because in the last stage, cancer spreads to other body parts such as lymph nodes or fluids surrounding the tissue and is unable to remove completely.

Q5. What is immunotherapy?

Ans. Immunotherapy aims to boost our immune systems to fight cancer cells. It helps the immune system to find and attack the cancer cells present in the body using living cells or living substances made from living cells. So it is also called biological therapy.

Updated on: 29-Dec-2022


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