Diagnosis & staging
These are tests that may be used to diagnose this type of cancer.
- A chest X-ray is one of the most useful examination tools.
- CT (computerized tomography) scans can show in 3D the relationship of the lung cancer to other structures of the chest, and can show the possible spread of cancer to the lymph nodes.
- MRI magnetic resonance imaging may be useful in some circumstances.
- PET (Positron Emission Tomography) scans can be used to look at lung cancers and assess the relationship to other structures in chest and show possible spread to other organs.
- To make a diagnosis of lung cancer, cells must be examined under a microscope.
- Cells may come from sputum samples, pleural fluid (fluid on the lungs), brushings or washings of the bronchi (sample gathered from a bronchoscopy) or from a biopsy (sample) of the lung cancer.
- A bronchoscopy is a procedure that can be used to diagnose lung cancer and determine the extent of the disease. This is usually performed with a fibre-optic bronchoscope, which is a flexible viewing tube with lighting. The bronchoscope is inserted down the throat into the trachea and bronchi. It can also grab bits of tissue, and a biopsy may be taken at this time. A local or general anesthetic may be used.
- A needle biopsy may also be used for diagnosis. The doctor is guided by a CT scan or x-rays and inserts a needle through the chest wall into a suspected tumour and draws out a tissue sample. Lung collapse may be a complication with this procedure.
- Thoracentesis is the removal of fluid from the chest. A needle is inserted through the chest to the space between the lung and the chest wall to draw out fluids. This can be used for diagnosis to look at the cause of fluid on the lungs. This can be used to analyze the fluid, or to relieve shortness of breath caused by large amounts of fluid in the pleural space. Occasionally this is combined with a procedure called a pleurodesis, to stick the lung to the chest wall. This usually involves the placing of a tube in the chest for one to three days during a hospital stay to ensure that all of the fluid has been removed.
- A mediastinoscopy and mediastinotomy can provide information on the spread to lymph nodes and is performed under general anesthetic.
- A mediastinoscope is inserted through a small v-shaped incision at the centre of the base of the neck and passed behind the sternum (breastbone) to lie directly in front of the trachea. Lymph nodes on either side can be seen and biopsied.
- A mediastinotomy involves a cut near the 2nd rib to gain access to the lymph nodes under the aorta. This is used in patients who have centrally located tumours in the left upper lobe.
- If there are lymph nodes that can be felt when a physician examines the patient, a needle biopsy may be performed.
- A diagnostic thoracotomy (surgically opening the chest to look at the lungs) may be necessary if other diagnostic procedures fail.
- Pleuroscopy is not used often, but can be valuable for patients who have undiagnosed fluid in the chest. A thoracoscope or fibre-optic bronchoscope is inserted into the pleural space. All of the space can be examined visually and fluid and tissue samples can be taken.
For more information on tests used to diagnose cancer, see our Recommended Websites, Diagnostic Tests
Types and Stages
There are two major kinds of lung cancer, small cell and non-small cell.
- Small cell lung cancers (SCLC) make up 10-15% of lung cancers.
- An older term for this kind of cancer is "oat cell" cancer, because of the shape of the cells. They are generally small and round, or oval, or shaped like oat grains.
- This is the most aggressive and fast-growing of all lung cancers.
- In many patients the cancer will have spread to other organs (distant metastases) at the time of diagnosis even if the primary tumour is small.
- Usually, small cell lung cancers are not treated surgically.
- Multidrug chemotherapy with radiation therapy is the usual treatment. Prophylactic (preventive) whole-brain radiotherapy may also be used.
- A long term cure is possible in about 20% of patients if the tumour is only in the chest (called 'limited stage').
- Small cell lung cancer is staged referring to limited (disease is isolated to an area that could be treated with a single field of radiation treatment) or extensive (disease is bulky or in multiple areas)
- Non-small cell lung cancers (NSCLC) – About 80% of all lung cancers are non-small cell. This category includes a number of different kinds of lung cancer. Some of them are squamous cell carcinoma, adenocarcinoma, and large cell (undifferentiated) carcinoma.
- Squamous cell carcinoma (epidermoid)
- About 30% of all NSCLC lung cancers are squamous cell.
- About 40-50% of NSCLC lung cancers are adenocarcinomas.
- This is the most commonly diagnosed lung tumour in women. [See note, Statistics]
- Non-smokers more frequently have this type of lung cancer.
- Large cell carcinoma
- This type of lung cancer occurs less frequently than other cell types (about 10%).
- Less common kinds of non-small cell lung cancer are adenosquamous carcinoma and carcinoid.
Staging describes the extent of a cancer. The
TNM classification system is used as the standard around the world for staging non-small cell lung cancers. In general a lower number in each category means a better prognosis. The stage of the cancer is used to plan the treatment.
T describes the site and size of the main tumour (primary)
N describes involvement of lymph nodes
M relates to whether the cancer has spread (presence or absence of distant metastases).
The tumour is contained, and has not spread.
The cancer has spread to lymph nodes within the lung.
Cancer is found in the lymph nodes outside the lung, in the centre of the chest and/or the primary tumour has invaded the chest wall or central structures within the chest.
The cancer has spread to other parts of the body.