Lung Cancer

Lung cancer at a glance

  • Lung cancer occurs when abnormal cells cause the growth of a cancerous tumor in the lungs, most commonly in the bronchi.
  • It is the leading cause of cancer-related death and the 2nd most common cancer in men and women.
  • Lung cancer is the most preventable cancer in the world; 85 percent of lung cancers are due to smoking, which increases a person’s chances of developing lung cancer by 200 percent.
  • Many people do not experience symptoms of lung cancer until it has spread to other parts of the body.
  • Treatment for lung cancer is dependent on the health of the patient and the stage of the cancer.
  • Common treatments include surgery, chemotherapy, radiation therapy and CyberKnife radiotherapy, an advanced form of radiation treatment. 

What is lung cancer?

Lung cancer is the growth of abnormal cells that causes a lung tumor. It can occur anywhere in the lungs, however the most common form originates in the bronchi. The major types of lung cancer are small-cell lung cancer and non-small cell lung cancer.

This is the second most common cancer in both men and women, shortly behind prostate and breast cancer. Although lung cancer is the second most common cancer, it is the first most preventable cancer and the leading cause of cancer related death in the world.

Humans have a set of two lungs. Lungs are large, spongy organs that facilitate the gas exchange of oxygen and carbon dioxide throughout the body. The anatomy of the lungs resembles an upside-down tree.

Air is inhaled through the mouth and nose and into the trachea or windpipe, which is like the trunk of the tree. The trachea transports the air throughout the lungs through branches called bronchi (large branches) and bronchioles (small branches). The bronchioles have little air sacks, called alveoli. This is where the exchange of oxygen and carbon dioxide takes place.

Lung cancers most often begin in cells that line the bronchi, and to a lesser degree in other areas of the lung, such as the bronchioles and alveoli. It’s thought that pre-cancerous changes in the lung start lung cancers.

Two types of lung cancer


Small-cell lung cancer is the most aggressive form of lung cancer because of its tendency to spread before symptoms even appear. Small-cell lung cancer can spread to other parts of the body (metastasize) in as little as 90 days. Small-cell lung cancer usually originates in the central bronchi and can spread to the liver, bones and brain.

Non small-cell

Non small-cell lung cancers include:

  • Squamous cell carcinoma is most common in men and smokers and accounts for about 30 percent of all lung cancer diagnoses. Squamous cell carcinoma typically originates in the central bronchi, which are the largest branches of the bronchi. This type of small-cell lung cancer is the most curable due to its slow spreading nature and containment within the lungs.
  • Adenocarcinoma is most commonly found in women and smokers and accounts for about 40 percent of lung cancer diagnoses. Adenocarcinoma usually develops in the peripheral (outer) portion of the lungs. Adenocarcinoma can spread to the lymph nodes and other parts of the body.
  • Large cell carcinoma is the least common non small-cell lung cancer, only accounting for 10-15 percent of all lung cancer cases. Large cell carcinoma is groups of large, abnormal looking cancerous cells that originate in the outer edges of the lungs.


Often, early symptoms of lung cancer mimic asthma or cold symptoms. If any of the following symptoms persist for longer than a common cold (2­–3 weeks), a person should see his or her doctor.

  • Persistent cough
  • Shortness of breath
  • Wheezing
  • Coughing up mucus or phlegm
  • Coughing up blood
  • Changes in voice or hoarseness
  • Recurring lung problems such as pneumonia and bronchitis

Lung cancer that has spread to other parts of the body may have additional symptoms including:

  • Headache
  • Weight loss
  • Muscle loss
  • Fatigue and general weakness
  • Loss of bone density and increased instances of bone fractures
  • Neck or facial swelling.

Who is at risk for lung cancer?

Smoking causes 85 percent of lung cancer. People who smoke a pack of cigarettes a day are 20 times more likely to develop lung cancer than non-smokers. Second hand smoke inhalation can also put a person at risk for lung cancer, especially if they are genetically predisposed.

Studies have shown that since lung cancer, like many other cancers, runs in families, there may be a genetic component to the disease.

Other causes include:

  • Exposure to asbestos
  • Exposure to uranium dust
  • Exposure to radon, a radioactive gas
  • Air pollution
  • Genetics
  • People with scleroderma, a skin disease which commonly affects the lungs that causes skin to become hard and tight
  • People with tuberculosis, a bacterial infection commonly found in the lungs.

Treating Lung Cancer