Lung Cancer

How is lung cancer diagnosed?

Tests and procedures used to diagnose lung cancer include a combination of imaging tests and biopsy of an area of abnormal growth detected on a scan, or on clinical examination. 

Initial imaging tests 

• Chest X-ray: A chest X-ray is used to identify abnormalities in the lungs that can then be investigated further with a CT scan. 
• Computerised Tomography Scan (CT) Scan: CT scans use x-ray beams rotated around the body to produce a series of images that produces a complete picture of the part of the body that is being scanned. A CT scan can show details such as the size, shape and position of any lung tumours. It can also help detect areas where the cancer may have spread to, such as the lymph nodes between the lungs or in the neck, or other organs such as the adrenal glands, liver and brain.

Tests to determine the stage of lung cancer 

After a lung cancer diagnosis is confirmed, further tests may be performed to determine if the cancer has spread to other parts of the body. This information is used to decide the stage of lung cancer. Different stages of lung cancer require different types of treatment.

Examples of these tests:

• Bone Scan: A bone scan can detect if cancer has spread from the lung to the bones. In this procedure, a small amount of radioactive material called a tracer is injected and a scan is done to see how the tracer is absorbed, as this can indicate the presence of cancer spread in the bones. 
• Positron Emission Tomography (PET) Scan: During a PET scan, a radioactive glucose solution is injected into the body. This is absorbed by cells in the body that are active and growing quickly, indicating the possible presence of cancer in these areas. The areas of glucose uptake can be identified with a special camera, which indicates active areas of growth. 
• Magnetic Resonance Imaging (MRI) Scan: Like CT scans, MRI scans provide detailed images of the body and are most often used to look for possible spread of lung cancer to the brain or spinal cord. MRI scans use radio waves and strong magnets to produce images instead of x-rays. 
• Mediastinal staging: In patients suspected to have stage 3 lung cancer, additional biopsy procedures may be recommended to determine if the mediastinal lymph nodes (located between both lungs) are affected by lung cancer. This will help doctors to decide between surgery or radiotherapy for the patient. Examples of these biopsy procedures are: 
• Endobronchial Ultrasound: In this test, a bronchoscope, which is a device used to see the inside of the airways and lungs, is fitted with an ultrasound transducer. If suspicious lymph nodes are identified, a needle is passed through the device to obtain a biopsy. 
• Mediastinoscopy: This is a minor surgical procedure done under general anaesthesia to get samples from lymph nodes in the chest. A small cut is made in the front of the neck and a small lighted device is inserted in the area behind the sternum (breast bone) to identify lymph nodes in the chest to be removed for biopsy. 
• Video-Assisted Thoracoscopic Surgery (VATS): This is a surgical procedure done under general anaesthesia to get samples from lymph nodes in the chest. One or more small incisions are made on the side of the chest to allow the surgeon to use a camera to identify lymph nodes inside the chest to be removed for biopsy. 

Stages of lung cancer 

Small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) are staged differently. 

SCLC 

• Limited stage: Cancer cells are only on one side of the chest and can be encompassed and treated with radiotherapy. 
• Extensive stage: Cancer cells have spread to the other side of the lungs and/or other parts of the body. 

NSCLC 

• Stage 1-3: Cancer cells have grown into lungs at the area they originated and may have spread to nearby lymph nodes but not to the other lung or other parts of the body. 
• Stage 4 (metastatic): Cancer cells have spread to other parts of the body away from the original lung tumour. Common sites of spread include the other lung, brain, liver, bone and adrenal gland. 

Molecular/ Biomarker testing (for NSCLC) 

NSCLC may be further divided into different subtypes based on molecular testing of the lung biopsy specimen for certain genes or proteins. These results are used to determine the type of treatment recommendation. 

Molecular testing is usually done on biopsy samples. However, in some situations when the biopsy specimen is not available, the quantity is not enough for further tests, or where the biopsy cannot be performed, a blood test can be done to determine the molecular profile of the cancer. This is referred to as a “liquid biopsy”.