Diagnosing lung cancer

Tests to confirm diagnosis

If a tumour is suspected after a chest x-ray or CT scan, you will need further tests to work out if it is lung cancer.

FDG PET–CT scan

This scan combines a PET (positron emission tomography) scan, with a CT scan in one machine. As well as helping with the diagnosis, a PET scan can provide detailed information about any cancer that is found.

First, a small amount of safe radioactive glucose solution called fluorodeoxyglucose (FDG) is injected into a vein, usually in your arm. You will be asked to sit or lie quietly for 30–90 minutes while the glucose solution travels around your body. Then you will lie on a table that moves through the scanning machine very slowly. The scan will take about 30 minutes.

Cancer cells take up more of the glucose solution than normal cells do, so they show up more brightly on the scan. Sometimes a PET scan is done to work out if a biopsy is needed or to help guide the biopsy procedure. You will need to fast (not eat or drink) before having this scan.

Biopsy

The most common way to confirm a lung cancer diagnosis is by biopsy. This is when small sample of tissue is taken from the lung, lymph nodes, or both. The tissue sample is sent to a laboratory, where a specialist doctor called a pathologist looks at the sample under a microscope. There are various ways to take a biopsy. 

CT-guided lung biopsy

First, you will be given a local anaesthetic. Then, using a CT scan for guidance, the doctor inserts a needle through the chest wall to remove a small sample of tumour from the outer part of the lungs. You will be monitored for a few hours afterwards. There is a small risk of damaging the lung, but this can be treated if it happens.

Bronchoscopy

The doctor will look inside the large airways (bronchi) using a bronchoscope, a flexible tube with a light and camera. A bronchoscopy is usually performed under light sedation, so you will be awake but feel relaxed and drowsy. You’ll also be given a local anaesthetic (a mouth spray or gargle) so you don’t feel any pain during  the procedure. The doctor will then pass the bronchoscope into your nose or mouth, down the trachea (windpipe) and into the bronchi. 

Samples of cells can be collected from the bronchi using either a “washing” or “brushing” method where fluid is injected into the lung and then removed, or a brush-like instrument is used to remove cells.

Endobronchial ultrasound (EBUS)
This is a type of bronchoscopy that allows the doctor to see deeper in the lung using an ultrasound probe. During this test, the doctor may also take cell samples from a tumour, from the outer parts of the lung, or from lymph nodes 
in the area between your lungs (mediastinum). Samples from the lymph nodes can help to confirm whether or not they are also affected by cancer.

You will have light sedation and local anaesthetic, or a general anaesthetic. The doctor will then put a bronchoscope (a thin tube with a small ultrasound probe on the end) into your mouth. The bronchoscope will be passed down your throat until it reaches the bronchus. The ultrasound probe uses soundwaves to create pictures that show the size and position of a tumour.

After a bronchoscopy, you may have a sore throat or cough up a small amount of blood. These side effects usually pass quickly but tell your medical team how you are feeling so they can monitor you.

Endoscopic ultrasound (EUS)

Sometimes, an endoscopic ultrasound is used to check whether the lung cancer has spread to the lymph nodes in the mediastinum. In an endoscopic ultrasound, a probe is put into your mouth and down your oesophagus, and a cell sample is taken from the lymph nodes. You do not need any sedation or anaesthetic for EUS.

Mediastinoscopy

This type of biopsy may be done if larger samples from the lymph nodes found in the area between the lungs (mediastinum) are needed. You will have a general anaesthetic, then the surgeon will make a small cut (incision) in the front of your neck and pass a thin tube down the outside of the trachea. You can usually go home on the same day as having a mediastinoscopy, but sometimes you may need to stay overnight in hospital.

Thoracoscopy

If other tests are unable to provide a diagnosis, you may have a thoracoscopy. This uses a thoracoscope – a tube with a light and camera – to look at and take a tissue sample from the lungs or around the outer pleura. 

It is usually done under general anaesthetic with a type of keyhole surgery called video-assisted thoracoscopic surgery. Sometimes a simpler procedure called a medical thoracoscopy can be done as a day procedure with light sedation.

Biopsy of neck lymph nodes

The doctor may take a sample of cells from the lymph nodes in the neck with a thin needle. This is often done by a radiologist using an ultrasound for guidance.

Other biopsies

If there is concern that the cancer may have spread to other organs, such as the liver, different types of biopsies may be done.

Other tests

In some circumstances, such as if you are not well enough for a biopsy, mucus or fluid from your lungs may be checked for abnormal cells.

Sputum cytology

In this test, a sample of mucus from your lungs (called sputum or phlegm) is examined to see if it contains cancer cells. Sputum contains cells that line the airways, and is not the same as saliva. To collect a sample for this test, you will be asked to cough deeply and forcefully into a small container. You can do this at home in the morning before eating or drinking. The sample can be kept in your fridge until you take it to your doctor, who will send it to a laboratory to check under a microscope.

Pleural tap

Also known as pleurocentesis or thoracentesis, this procedure drains fluid from around the lungs. A pleural tap can help to ease breathlessness (see pages 48–49), and the fluid can be tested for cancer cells. It is mostly done with a local anaesthetic, with the doctor – often a radiologist – using ultrasound to guide the procedure.

Molecular tests

Biopsy samples may be tested for gene changes or specific proteins in the cancer cells (biomarkers). These tests are known as molecular tests and they help work out which immunotherapy and targeted therapy drugs may help treat the cancer.

Gene changes – Genes are found in every cell of the body and are inherited from both parents. If something triggers the genes to change (mutate), cancer may start growing.
A mutation that occurs after you are born (acquired mutation) is not the same thing as abnormal genes that can be inherited from your parents. Most gene changes linked to lung cancer are not inherited. Lung cancers with gene mutations may be treated with a type of drug therapy called targeted therapy.

Proteins – If certain proteins are found in the biopsy sample from an NSCLC, the cancer may respond to immunotherapy. The most common protein tested for is called programmed death 
ligand-1 (PD–L1) on the surface of the cancer cells.

Further tests

If the tests described in this chapter show that you have lung cancer, you will have further tests to see whether the cancer has spread beyond the lung to other parts of the body or the bones. You may also have a CT or MRI (magnetic resonance imaging) scan of the brain.

If a PET–CT scan is not available or the results are unclear, you may have a CT scan of the abdomen (belly) and pelvis or a bone scan. For more information, talk to your doctor or call Cancer Council 13 11 20.

Key points about diagnosing lung cancer

Diagnostic tests

The tests to diagnose lung cancer may include:

• chest x-ray
• CT scan of the lungs, lymph nodes and other organs
• lung function (spirometry) and blood tests
• FDG-PET (with or without) CT scan
• biopsy – tests a tissue sample removed from your chest by CT-guided lung biopsy, bronchoscopy, endobronchial ultrasound (EBUS), endoscopic ultrasound (EUS), mediastinoscopy or thoracoscopy
• sputum cytology – tests a sample of mucus (sputum) from the lungs
• pleural tap (pleurocentesis or thoracentesis) – tests a sample of fluid drained from the lungs.

Molecular and further tests

Other tests may be used to provide more information about the cancer, help work out if it has spread, and guide treatment. These may include:

• molecular tests – test the biopsy sample to identify genes or proteins in the cancer cells
• CT or MRI scans of the brain or bones.

Staging and prognosis

• The specialist will tell you the stage of the cancer, which describes how much cancer there is and whether it has spread to other parts of the body.
• You may also wish to discuss the prognosis, which is the expected outcome for people with the same type and stage of cancer as you.

Staging lung cancer

Diagnostic tests help show what type of lung cancer you have and how far it has spread. Called staging, this helps your doctors recommend the best treatment for you. 

Both NSCLC and SCLC are staged using the TNM (tumour-nodes metastasis) system, which considers the size of the tumour, whether it has affected lymph nodes and whether it has spread. This information may be combined to give the lung cancer an overall stage of 0, 1, 2, 3 or 4 (often written in Roman numerals as I, II, III or IV). 

Sometimes, SCLC is staged using a different system in which the cancer is classified as either limited stage or extensive stage. For more information about these 2 staging systems (see table).

Staging NSCLC

In the TNM system, each letter is given a number (and sometimes another letter) to show how advanced the cancer is. For example, T1 means the tumour is 1 cm or smaller, while T4 means the tumour is more than 7 cm, or has spread into nearby organs, or there are 2 or more separate tumours in the same lung. 

Staging SCLC

Sometimes, SCLC is staged using a 2-stage system in which the cancer is classified as either limited disease or extensive disease.

Prognosis

Prognosis means the expected outcome of a disease. You may wish to discuss your prognosis and treatment options with your doctor, but it is not possible for anyone to predict exactly how the disease will respond to treatment. Instead, your doctor can give you a general idea of the outlook for people with the same type and stage of lung cancer. 

To work out your prognosis, your doctor will consider:

• your test results
• the type and stage of lung cancer
• the rate and extent of tumour growth
• other factors such as your age, fitness and overall health, 
  and whether you smoke or vape.

Discussing your prognosis and thinking about the future can be challenging and stressful. It is important to know that although some statistics for lung cancer can be frightening, they are an average and may not apply to your situation. Talk to your doctor about how  to interpret any statistics that you come across, as well as the best and worst possible outcomes. This information can help you make treatment decisions.

As in most types of cancer, the outcomes of lung cancer treatment tend to be better when the cancer is found and treated early. Newer drug treatments such as immunotherapy and targeted therapy have given promising results in many people with advanced lung cancer and are bringing hope for a longer, healthier life to those who have lung cancer that has spread.

For certain circumstances, these therapies are now being used for earlier stage lung cancer.