Diseases & Conditions

 

Lung Cancer

Diseases & Conditions

What is lung cancer?

Lung cancer is a cancer that starts in the lungs. It happens when the cells in the lungs start to multiply in an uncontrolled way and form tumors. The cells do not function normally and they keep growing. There are two main types of lung cancer.1

  • Small cell lung cancer, which is a type of cancer made up of small round cells in the lungs and accounts for 10% to 15% of all lung cancers.2
  • Non-small lung cancer, which grows in cells other than small cells inside the lungs and accounts for 85% to 90% of all lung cancers. 2 There are 3 main subtypes of non-small lung cancer which look different under a microscope differing in size, shape and chemical composition:
    • Squamous cell carcinoma is often linked to a history of smoking and accounts for 25% to 30% of all lung cancers.2
    • Adenocarcinoma occurs mainly in current or former smokers and accounts for 40% of all lung cancers.2
    • Large cell carcinoma is a type of lung cancer that grows very fast which makes it harder to treat and accounts for 10% to 15% of all lung cancers.2

Lung cancer is one of the most common malignant diseases and leading cause of cancer death worldwide with estimated more than 1.3 million new cases each year.1 In 2007, lung cancer was the fourth leading cause of death in men in Saudi Arabia.3

What are the stages of lung cancer?

Lung cancer is assigned a stage from I to IV in order of severity.4

Stage I

The cancer is limited to the lungs

Stage II

The cancer is small but cancer cells have spread to the lymph glands nearest to the affected lungs (lymph glands are a part of the immune system which help the body fight infection)

Stage III

The cancer cells have spread to the lymph glands in the other side

Stage IV

The cancer has spread to another part of the body such as the liver or bones

 

What causes lung cancer?

  • Smoking: Smoking is the largest single cause of lung cancer, responsible for the majority of lung cancer cases, and continues to rise.5 Since 1970 the prevalence of smoking has increased in Saudi Arabia, as in the rest of the world, and this will likely lead to a lung cancer epidemic in the coming decades.6
    • Secondhand smoking: Breathing in the smoke of others can increase the risk of developing lung cancer.
  • Radon: Radon is a naturally occurring radioactive gas that is formed during the decay from uranium found in certain houses, workplaces and in water. Radon is one likely causative factor for the 10–15% of lung cancers that occur among non-smokers. 6
  • Personal or family history of lung cancer: The risk of lung cancer is higher in people who have pre-existing lung cancer history. Moreover, people with a parent, sibling or other first-degree relative with lung cancer have an increased risk of the disease.
  • Asbestos: Asbestos refers to a set of six naturally occurring fibrous minerals. It has been shown that exposure to asbestos can lead to lung cancer (especially causing cancer in the mesothelioma, which is the lining surrounding the lungs).
  • Exposure to certain chemicals: There are chemicals found in some workplaces that can increase lung cancer risk, especially for smokers. These chemicals include radioactive such as uranium, arsenic beryllium, cadmium, silica, vinyl chloride, nickel compounds, coal products, mustard gas and diesel exhaust.
  • Air pollution: In cities, air pollution appears to increase the risk of lung cancer.

What are the signs and symptoms for lung cancer?

The symptoms of lung cancer can include:7

  • Coughing up blood and phlegm
  • A persistent cough that does not go away or worsen
  • Shortness of breath
  • Wheezing
  • Hoarseness
  • Chest or shoulder pain
  • Feeling tired or weak
  • Weight loss and loss of appetite
  • Recurrent infections such as bronchitis and pneumonia

It is important to note that most lung cancer patients do not show any symptoms at early stages. Symptoms start to appear when the lung cancer had spread too far. The lung cancer patient may only experience one or two of these symptoms. Since many healthy people may experience these symptoms from time to time, it can sometimes be difficult for the doctor to diagnose lung cancer. However, it is important that lung cancer be diagnosed at early stages when treatment is more likely to be effective.

Can lung cancer be prevented?

Not all lung cancers can be prevented, but there are some ways to reduce the risk of getting lung cancer.8

  • The most straightforward method of preventing lung cancer is to stop smoking and to avoid secondhand smoking.
  • Reduce the exposure to radon by having homes tested and treated, if needed
  • Avoid exposure to chemicals known to possibly cause lung cancer
  • Eat a healthy diet with lots of fruits and vegetables. It has been shown that a healthy diet may also help reduce the risk of developing lung cancer.9
  • Exercise most days of the week

How is lung cancer diagnosed?

Doctors use many tests to diagnose lung cancer:10

  • Biopsy: A biopsy is the removal of a small amount of tissue from the lungs to examine if abnormal cells appear under a microscope.
  • Molecular testing for the tumor: This test identifies if specific genes, proteins and other factors unique to lung cancer are present.
  • Sputum cytology: This test examines coughing-induced phlegm for abnormal cells.
  • Bronchoscopy: The bronchi, or tubes leading into the lungs, can be viewed through an instrument called a bronchoscope, allowing doctors to see abnormal areas.
  • Mediastinoscopy: It examines the lymph nodes of the lungs in the center of the chest underneath the breastbone using a lighted tube.
  • Imaging tests:
    • X-ray image
    • Computed tomography (CT) scan
    • Positron emission tomography (PET) scan
    • Magnetic resonance imaging (MRI)

How is lung cancer treated?

Lung cancer treatment will depend on the type of lung cancer a patient has. Overall, there are five basic ways to treat small cell lung cancer and non-small cell lung cancer:10

  1. Surgery: The aim of a surgery is to remove lung cancer tissues. The surgery procedures include:
  • Lobectomy: The lungs have five lobes, three in the right lung and two in the left lung. The removal of an entire lobe of the lung is called a lobectomy. It is currently thought to be the most effective type of surgery, even when the lung tumor is very small.
  • A wedge resection: It consists of removing a small section of the lung that contains the tumor.
  • Segmentectomy: It consists of removing a large section of the lung that contains the tumor but not an entire lobe.
  • Pneumonectomy: It consists of removing a whole lung.

 

  1. Radiation therapy: Radiation therapy is the use of high energy X-rays or other particles to destroy cancer cells.

 

  1. Chemotherapy: Chemotherapy uses drugs to kill cancer cells. This is done by stopping the multiplication of cancer cells. The drug is given intravenously or orally for a specific number of cycles given over a set period of time according to international guidelines. There are different kind drugs for the different types of lung cancers. The side effects of chemotherapy depend on the individual and the dose used, but they can include fatigue, risk of infection, nausea and vomiting, hair loss, loss of appetite, and diarrhea. These side effects usually disappear once treatment is finished.

 

  1. Targeted therapy: Targeted therapy is a new cancer treatment that works by targeting specific abnormalities in cancer cells. It targets specific genes, proteins and tissues of the cancer. This type of treatment blocks the growth and spread of cancer cells while limiting damage to healthy cells. Targeted therapy drugs are often used in combination with chemotherapy drugs.

 

  1. Immunotherapy: Immunotherapy, also called biologic therapy, is designed to stimulate a patient’s own immune system to recognize and fight the cancer more effectively.

 

 References

 

  1. Panov, Sasho Z. "Molecular biology of the lung cancer." Radiology and Oncology 39.3 (2005).
  2. "Lung Cancer Prevention and Early Detection." American Cancer Society. Web. 17 Nov. 2015. <http://www.cancer.org/acs/groups/cid/documents/webcontent/acspc-039558-pdf.pdf>.
  3. Cancer incidence and survival report Saudi Arabia 2007, special edition. Ministry of Health Saudi Cancer Registry, 2007. Available at: http://www.scr.org.sa/reports/SCR2007.pdf
  4. Lung Cancer - Non-Small Cell - Treatment Options (Cancer.Net). http://www.cancer.net/cancer-types/lung-cancer-non-small-cell/treatment-options
  5. The Cancer Council Australia. Clinical Practice Guidelines for the Prevention, Diagnosis and Management of Lung Cancer. Sydney: NH&MRC. 2004.
  6. Howington, John. "The first Saudi lung cancer guidelines." Annals of thoracic medicine4 (2008): 127.
  7. Lung cancer symptoms (Lung cancer symptoms). http://www.cancerresearchuk.org/about-cancer/type/lung-cancer/about/lung-cancer-symptoms
  8. Lung cancer (Prevention). http://www.mayoclinic.org/diseases-conditions/lung-cancer/basics/prevention/con-20025531
  9. Khan, Naghma, and Hasan Mukhtar. "Dietary agents for prevention and treatment of lung cancer." Cancer letters 359.2 (2015): 155-164.
  10. Lung Cancer - Non-Small Cell - Diagnosis (Cancer.Net). http://www.cancer.net/cancer-types/lung-cancer-non-small-cell/diagnosis