Lung cancer

There are two major types of lung cancer and are categorized as small cell lung cancer and non-small cell cancer.

Non-small cell lung cancer: This is most common and accounts for about 80 to 90 percent of all lung cancer. The most common types are;

• Adenocarcinoma which is the most common type and originates from the mucous producing cells of the lungs. It occurs in about 40 to 45 percent of all lung cancer. They tend to develop quickly and spread to other parts of the body especially the brain. Other areas are the lymph nodes, liver, adrenal, bone and other parts of the lung.
• Squamous cell carcinoma originates from the epithelial cell lining the air passages. They tend to be slower growing but it also can spread to other parts of the body like the adenocarcinoma and is most associated with a smoking history. It occurs in about 20 to 25 percentof all lung cancer.
• Large carcinoma is less common about 10% to 15% of all lung cancer and also has a tendency to spread to all parts of the body.

Small cell lung cancer

This is less common and occurs about 10 to 15 percent of cell lung cancer. They have a tendency to spread early to other parts of the body. Usually by the time they are discovered they are rather extensive. Because they are rapidly dividing they do respond to chemotherapy and they are generally treated by chemotherapy and radiation. Surgery is limited to localised disease which is uncommon.

Symptoms of lung cancer

Most lung cancers are asymptomatic until they are already well established or spread to other parts of the body. Surgery for localised disease is only possible in about 10 to 15 percent of cases by the time they are discovered.

However, if symptoms do appear, it includes

1) Persistent coughing

2) Coughing out blood (Hemoptysis)

3) Unexplained weight loss or appetite

4) Hoarseness of voice

5) Shortness of breath

6) Swelling in the face or upper extremities

7) Unexplained pain in the back, chest, shoulder or leg.

Diagnosis of lung cancer

Difficult to diagnose in its early stage as there are no symptoms. Diagnostic test include:-

• Sputum test - Cancer cells may be present in the phlegm.
• Chest X-ray (CXR) - Small or large lesion can be seen.

Computer tomography  (CT or CAT) scan - Special X-ray creating series of sliced images of the inside of the lung and more sensitive than CXR.

Position emission tomography (PET) scan - This technique uses radioactive glucose substances which can detect a cancerous tumour because more of the radioactive glucose material is absorbed by the rapidly dividing cancer cells compared to the surrounding cells causing it to light up on the scan.

Bronchoscopy - This is an instrument that looks into the airways (bronchus) and allows the doctor to see any tumour and also to remove small pieces of tissue (biopsy) for study under the microscope.

• Needle aspiration biopsy – A needle is used to remove some tissue from the lung for microscopic study and is done through the skin under CT- image guidance.
• Mediastinoscopy- A small incision is made above the breast bone in the neck and allow a lighted scope to pass into the mediastinum. (the space between the lung) to remove some tissue or piece of lymph node for microscope study.
• Open lung biopsy- Usually this is done through a scope inside the chest, (videothorascope with a camera inbuilt in the scope) inserted through a small incision and allow visualization of the lung and tissue sample can be taken from the tumour in the lung.

All or some of the tests may be used to determine if the lung tumour is cancerous and to evaluate whether it is localised or spread to other parts of the body- a process known as staging.

How is lung cancer treated

Treatment depends on the type of the cancer, the stage of the disease and the patient overall-condition.

• Surgery- if the disease is localised in a fit individual.
  • This can include :
    •  Limited wedge resection( taking out small area containing the cancer)
    •  Lobectomy (removing a lobe of the lung)
    • Pneumonectomy  (removal of the entire lung on one side)
    • Chemotherapy: use of drugs to kill the cancer cells in the lung and those that have spread beyond the lung to other parts of the body. This can be in the form of a pill or drugs injected into the blood. They can be combined with radiation or surgery.
    • Radiation Therapy: Use of high energy x-rays to kill the cancer cells which can be administered from outside the body (external high beam radiation) or putting it by scope inside the tumour where the cancer cells are found (internal radiation therapy).
    • They can be combined with chemotherapy or surgery.

Prognosis of people with lung cancer

This depend on the type and stage of the lung and the patient general health. As a rule early lung cancer if detected and treated have a better prognosis then if detected in the

advanced stage of the disease. Hence, early detection is the key to improve prognosis but unfortunately, there is no proven screening test for lung cancer although recent date suggest some of low dose CT screening for lung cancer in high risk individual may be useful.

Prevention of lung cancer

Avoid smoking yourself and be in smoking environment (passive smoking) and taking precaution when working in asbestos, fumes and chemical environment.