Lung cancer occurs when cells in the lung grow out of control and form a tumor. A tumor can be noncancerous or cancerous. A cancerous tumor is a collection of a large number of cancer cells that have the ability to spread to other parts of the body. The mortality rate of lung cancer depends on the type of the cancer.
 
There are two main types of lung cancer, defined by how the cells look under the microscope. These two types of lung cancer develop and are treated differently.

• Small cell lung cancer (SCLC) – About 10-15% of lung cancer are small cell lung cancer. This type of cancer tends to spread faster than the non-small cell lung cancer, causing death more quickly. Treatment by medication or radiation is preferred to surgery.
• Non-small cell lung cancer (NSCLC) – This type of lung cancer accounts for 85 to 90% of lung cancer. It spreads more slowly than small cell lung cancer and can be cured by surgery if detected at the early stage.

The specific cause of lung cancer remains unknown. However, certain factors increase the chances of developing lung cancer.

• Cigarette smoking – It can be the main cause of lung cancer. Cigarette smokers are 10 to 30 times more likely to develop lung cancer than nonsmokers. Nicotine in cigarettes destroys lung cells, causing abnormalities of the cells. The likelihood of developing cancer depends on the number of the cigarettes usually smoked and number of the years a person has been smoking.
• Toxic substances and environmental pollution – Cigarette smoke, asbestos, radon, arsenic, radiation and other chemicals, including dust and vapors from nickel, chromium and other metals, can be risk factors for lung cancer.
• Age – The older a person is, the higher the risk of lung cancer. In general the risk increases after the age of 40, but even those younger may develop lung cancer.
• Family history – Those with the history of lung cancer in parents and siblings are at a higher risk for lung cancer when compared with those without this family history, even if they are nonsmokers.

 
People at risk for lung cancer should see their doctor to learn ways to reduce their chances of developing lung cancer and for regular health check-ups. For those have had lung cancer and undergone treatment, regular follow-up visits are required in case of a relapse.

Lung cancer screening is essential for early detection of lung cancer, so it can be treated successfully in its early stage. At present there is no simple test or method for self-examination, as there is for breast cancer. However, a new test called a low-dose helical computerized tomography can be used to screen for and diagnose lung cancer.
 

Normally, people with early lung cancer do not show any of the symptoms. However, when the disease spreads, the following symptoms may be experienced. 

• Chronic cough (dry or productive cough)
• Breathing problems, such as the shortness of breath
• Wheezing
• Chest pain
• Hemoptysis
• Hoarseness
• Frequent lung infections, such as pneumonia
• Weakness or fatigue
• Unexplained weight loss

 
All of these symptoms are not always related to lung cancer as there are many diseases that present in the same way. If you do experience these symptoms, you should see your doctor as soon as possible.

If lung cancer is suspected, the doctor will carry out a physical examination, phlegm check, and chest x-ray. More examinations may be required to confirm the diagnosis, such as:

• Biopsy
  • Fine-needle aspiration – The doctor inserts a small needle through the chest and directly into the lung tumor to remove a small sample of tissue for testing. Often a chest CT scan or special x-ray machine called a fluoroscope is used to guide the needle.
  • Bronchoscopy – The doctor passes a thin, flexible tube with a light on the end into the mouth or nose, down through the main windpipe, and into the breathing passages of the lungs. Tiny tools inside the tube will take samples of fluid or tissue, which will then be examined by the pathologist.   
  • Thoracentesis – A needle is inserted through the chest wall and into the space between the lung and the wall of the chest where fluid is collected for analysis for cancer cells.
  • Mediastinoscopy – The surgeon examines and takes a sample of the lymph nodes in the center of the chest (underneath the breastbone) by making a small incision at the top of the breastbone.
  • Thoracoscopy – The doctor will insert a camera inside a thin tube to look inside the chest to see where the cancer is and incise a tissue sample from the lung for examination.
• Imaging tests of lung cancer
  • CT scan and MRI – These tests enable the doctor to determine the location and size of the abnormal cells in the lung.
  • Positron emission tomography (PET) scan – A mixture of sugar and radioactive substance will be injected intravenously. The lung cancer cells absorb this sugar mixture faster and in larger amount than normal cells. They will appear brighter. This enables the differentiation between normal cells and cancer cells.
  • Photon-Counting Detector CT (PCD-CT), combined with artificial intelligence (AI), is a breakthrough in medical imaging technology

The staging of lung cancer is determined by the location of cancer cells, the size of the cancer cells and whether they have spread from where they initially began. The stage of the cancer plays a significant role in the treatment as it enables the doctor to decide the appropriate treatment to cure the disease, prolong the patient’s life or improve the quality of life.

• Stages of small cell lung cancer
  • Limited stage – Cancer cells are located only in the lung area.
  • Extensive stage – Cancer cells have spread to other parts of the body. 
• Stages of non-small cell lung cancer
  • Stage 1: Cancer cells are found only in the lung. They are not found in lymph nodes and have not spread to other organs.
  • Stage 2:
    • Stage 2A: The cancer cells are small and are found in nearby lymph nodes.
    • Stage 2B: The cancer cells are slightly larger and have spread to the lymph nodes near the affected lung or cancer cells have spread to another area such as the chest wall.
  • Stage 3:
    • Stage 3A: Cancer cells have spread to the lymph nodes far away from the affected lung or the cancer cells are found in the lymph nodes near the affected lung and have spread to other areas such as chest wall or the middle of the chest.
    • Stage 3B: Cancer cells have spread to the lymph nodes at the other side of the chest or to the lymph node above the collarbone or there is more than one tumor in the lung orthe cancer has grown into another area in the chest, such as the heart or esophagus or there is fluid containing cancer cells surrounding the lung.
  • Stage 4: Cancer cells have spread to other parts of the body such as the liver, bone, and brain.  

 

Treatment options depend mainly on the location, size, and stage of lung cancer. The patient’s health and mental conditions should also be taken under consideration.

1. Surgery

• The objective of the surgery is to remove cancer cells and lymph nodes of your chest.
• Not used for treatment of small-cell lung cancer that can rapidly spread to other organs.
• Used to treat non-small cell lung cancer stage 1, 2, and 3A.

2. Radiotherapy

• Uses high energy x-rays to kill cancer cells.
• Cannot be used to treat metastatic lung cancer.
• Takes a short period of time and causes no pain. However, possible side effects include difficulty swallowing, fatigue, loss of appetite, and skin irritation at the treatment site.

3. Chemotherapy – Use of drugs to kill cancer and delay the growth of cancer cells. Most chemotherapy used for lung cancer is injected into a vein.
4. Targeted therapy

• Targets only at cancer cells and does not affect the normal cells.
• Effective treatment and there are no side effects like chemotherapy.

5. Combination therapy – To be most effective cancer treatment is done using a combination of therapies, as deemed appropriate by your oncologist.

• Stop smoking if you are a regular smoker.
• When you have recovered physically, exercise regularly by walking at least 15-30 minutes a day to improve lung and heart function.
• See your doctor as scheduled to prevent relapse and the spread of cancer to other parts of the body (metastatic cancer).