Lung Cancer

What is lung cancer?

Lung cancer begins when cells in the lungs begin to divide and grow uncontrollably. This abnormal uncontrolled cell division leads to the formation of abnormal masses, called tumours, which impair the normal functioning of the lungs.

Lung cancer holds the highest incidence among all cancer types and remains the primary cause of cancer-related fatalities globally. In the context of India, lung cancer represents 5.9% of all cancer cases and accounts for 8.1% of all cancer-related deaths.  (reference: Singh N, et al. Lung Cancer in India.  JournalofThoracicOncologyVol.16No.8:1250-1266)

Smoking is often the primary cause of lung cancer, both in smokers and in non-smokers who are exposed to second-hand smoke, which means they remain in close contact with smokers for a long time. However, lung cancer can also be seen in people who have never smoked. Roughly 20% of people diagnosed with lung cancer have never smoked.

There are 2 main types of lung cancer:

Non-small cell lung cancer (NSCLC)

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer.  About 80% to 85% of lung cancers are NSCLC.  Adenocarcinoma and squamous cell carcinoma are the most common types. Adenosquamous carcinoma and sarcomatoid carcinoma are two less prevalent types of NSCLC.

Small cell lung cancer (SCLC)

Small cell lung cancer (SCLC) grows more quickly and is more difficult to treat than NSCLC. About 10% to 15% of all lung cancers are SCLC.  It is often found as relatively small in size and is already spread to other parts of the body when it is diagnosed.  Other specific types of SCLC include small cell carcinoma and combined small cell carcinoma.

What are the Risk Factors?

  • Smoking is a leading risk factor for lung cancer. Smokers are at a significantly greater risk of developing or succumbing to lung cancer than non-smokers. In fact, smokers are 15 to 30 times more likely to get lung cancer. Even smoking a small number of cigarettes each day or intermittently can heighten the risk of lung cancer. The risk of lung cancer is directly proportional to the duration of smoking. While quitting smoking can reduce the risk of lung cancer, it remains higher than the risk for individuals who never smoked. Nonetheless, quitting smoking at any age can significantly lower the risk of lung cancer.
  • Exposure to second-hand smoke: Second-hand smoke, which includes smoke from cigars, pipes, and cigarettes, also increases the risk of lung cancer. 
  • Exposure to carcinogens – A number of metals like arsenic, chromium, and nickel are known to be carcinogenic.  Similarly, exposure to asbestos is also linked to lung cancer.
  • Family history of lung cancer: The risk of lung cancer is higher if your parents, brothers, or sisters have had lung cancer.

What are the signs and symptoms?

Most of the time lung cancer does not lead to signs and symptoms in its earliest stage. Signs and symptoms typically occur only in the advanced stage of the disease which may include;

  • Persistent coughing with or without blood
  • Shortness of breath
  • Chest pain
  • Wheezing
  • Tiredness
  • Weight loss with no known reason

A cough or pneumonia that keeps returning after treatment could be an early sign of lung cancer, but it could also be a sign of less serious conditions.

So, if you are at higher risk for lung cancer, it’s important to get screened.

How is lung cancer diagnosed?

Lung cancer is diagnosed with the help of:

  • Medical history and physical examination.
  • X-ray images:  X-rays may be the first test to look for any abnormality in the lung. If anything is suspicious, further specialized imaging studies such as CT scans and MRI scans can be ordered to look size, shape, and location of the lung lesion (abnormality). PET scans are performed mainly to find out if cancer has spread.   
  • Sputum cytology involves examining mucus coughed up from the lungs under a microscope to check for cancer cells.
  • Thoracentesis: A procedure where a needle is used to remove fluid from the space between the lining of the chest and the lung. A pathologist examines the fluid under a microscope to check for cancer cells.
  • Biopsy, where a small sample of lung tissue is taken and examined under a microscope to determine if cancer cells are present. This can be done through a needle biopsy or a surgical biopsy.

What medications/treatments are used in lung cancer?

Lung cancer treatment depends on the type of lung cancer, its location, how far it is spread, and many other factors.

Treatments for lung cancer are designed to eliminate cancer from the body or slow down its growth. Treatments can remove cancerous cells, help to destroy them or stop them from multiplying or train your immune system to fight them. Symptomatic treatment is offered to relieve pain.

It includes,

  • Surgery:  Surgery is performed to remove the tumour and a small amount of healthy tissue around so that they do not leave any cancer cells behind. Sometimes it is performed to remove a whole lobe (section) of the lung or to remove part of the bronchus (sleeve resection). 
  • Chemotherapy:  Chemotherapy is a treatment where medications are used to stop the growth of cancer cells. This treatment either kills the cells or prevents them from dividing. Chemotherapy can be administered orally, through injections into a vein or muscle. When the drugs enter the bloodstream, they can travel throughout the body and target cancer cells wherever they may be (systemic chemotherapy).
  • Radiation therapy: Radiation therapy is a type of cancer treatment that involves using high-energy X-rays or other forms of radiation to destroy cancer cells or prevent them from growing.
  • Immunotherapy – Human bodies usually recognize cells that are damaged or harmful and destroy them. Cancer cells hide from the immune system to keep from being destroyed. Immunotherapy reveals cancer cells to our immune system so our own body can fight cancer.
  • Targeted Drug therapy:  It is a treatment where medications are used which identify and attack specific cancer cells. 

The healthcare provider will choose which course of therapy is best for you.

Can lung cancer be prevented?

There are many ways to lower the chances of getting lung cancer.

  • Do not smoke or use tobacco
  • Avoid second-hand smoke
  • Avoid carcinogens
  • Maintain a healthy diet
  • Do regular exercise
  • If you are at high risk, get a screening for lung cancer

Can lung cancer be cured?

Early diagnosis and early treatment can cure many cases of lung cancer. If the disease is caught early, the cure rate is high; around 90%. The rate drops greatly if cancer has spread to other parts of the body.

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