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Lung Cancer: Risk Factors, Diagnosis, Treatment

Lung cancer

Lung cancer is one of the most common causes of cancer-related disability and death in the world. It begins in the lungs and can spread to other organs in the body if left untreated. Humans have a pair of lungs that are located in the chest, through inhalation, the lungs take in oxygen, and release carbon dioxide on exhalation.


In 2020, the incidence of lung cancer in the world was 2,206,771 (11.4% of all cancers) and the total number of deaths was 1,796,144 (18%). The incidence of lung cancer is even higher in Asia as it is home to 59.6℅ of total lung cancer patients in the world with a mortality rate of 61.9%. This cancer is the major cause of cancer death in men and the second leading cause of cancer death in women worldwide. It is the most deadly cancer in the world with a 5-year prevalence of 58.2℅ in Asia.

Signs & symptoms of lung cancer

Signs and symptoms usually present when it has progressed to an advanced stage and may include:

  • Blood in sputum
  • Shortness of breath
  • Chest pain
  • Hoarseness
  • Weight loss
  • Bone pain
  • Headache

Risk factors of lung cancer

Active smoking

The risk of lung cancer is closely associated with the number of cigarettes smoked per day and the number of years smoked. 

Passive smoking

Individuals that are exposed to secondhand smoke are also at risk of being diagnosed with lung cancer.

Previous radiation therapy

Radiation therapy as treatment for another type of cancer may cause an increased risk of developing lung cancer.

Exposure to radon gas

The natural breakdown of uranium in soil, rock, and water produces radon, when radon particles mix in the air that is inhaled, they can accumulate in the lungs and cause cancer.

Exposure to asbestos and other carcinogens

Exposure to arsenic, chromium, or nickel can increase the risk of developing lung cancer, especially if the individual also smokes.

Family history

A positive family history of lung cancer in a parent or sibling can cause an increased risk of the disease.

Diagnosis of lung cancer


In populations with increased risk of lung cancer, annual screening is done using low-dose computed tomography (CT) scans. Such screening is offered to people over the age of 55 who have also smoked heavily for many years or who have quit in the past 15 years.

Tests to diagnose

  • Imaging tests such as chest X-rays and CT-scans
  • Sputum cytology
  • Tissue sample (biopsy): A biopsy is a technique in which a sample of abnormal cells may be removed for tissue diagnosis. Lung biopsies are done through:
    • Bronchoscopy – inserting a needle through a tube to obtain a tissue sample
    • Mediastinoscopy – making an incision at the base of the neck and inserting surgical tools behind the breastbone to take tissue samples from lymph nodes
    • Needle biopsy – using X-rays or CT scan images to guide a needle through the chest wall and into the lung tissue to retrieve suspicious cells

Staging tests

Imaging procedures include CT scans, magnetic resonance imaging (MRI), positron emission tomography (PET), and bone scans. 



Surgery is done to remove cancerous lung tissues and a margin of healthy tissue. Procedures to remove lung cancer include:

  • Wedge resection: A small section of the lung is removed that contains the tumour along with a margin of healthy tissue
  • Segmental resection: A larger portion of the lung is removed, but not an entire lobe
  • Lobectomy: An entire lobe of one lung is removed
  • Pneumonectomy: An entire lung is removed

In the event that the physician suspects the spread of cancer to the lymph nodes of the chest, lymph nodes are also removed and examined for signs of cancer.

Radiation therapy

High-powered energy beams from sources such as x-rays and protons are used to kill cancer cells in patients with locally advanced lung cancer. Radiotherapy can be given before or after surgery and can often be combined with chemotherapy. For advanced cancer, radiation therapy may also help relieve symptoms, such as pain.


Chemotherapy drugs can either be administered intravenously or orally. During chemotherapy, a combination of drugs is given in a series of treatments over weeks or months, this is often used post-surgery to eliminate remaining cancer cells. Chemotherapeutic drugs can be used alone or in combination with radiation therapy.


Immunotherapy is a treatment modality where the body’s immune system is instructed to fight cancer. It is generally reserved for people with locally advanced lung cancer and cancers that have metastasised.

Palliative care

Palliative care is usually provided to patients with end stage cancers where treatment is no longer possible and instead supportive care is provided to improve the patient’s quality of life. Studies have shown that people receiving palliative care survive almost three months longer than those receiving standard care.


 Lung cancer can cause complications, such as:

  • Blood in sputum
  • Chest pain
  • Fluid in the chest, pleural effusion
  • Metastasis to other parts of the body such as the brain or bones
  • Based on the site of metastasis, additional pain, nausea, headaches, or other signs and symptoms can occur 


 Lung cancer is a life-threatening condition in both males and females. The key to control cancer is to quit smoking as it is an important preventative measure in protecting ourselves and the people around us. It is important to maintain a healthy diet and active lifestyle while also undergoing cancer screening regularly. Presently there are no cures for the advanced stages of lung cancer or in instances where metastasis has occurred.

Article is written in conjunction with World Lung Cancer Day 2021, held on 1 Aug.

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