Tests to confirm diagnosis for lung cancer
If a tumour is suspected after an x-ray or CT scan, you will need further tests to work out whether it is lung cancer.
Learn more about:
- Other samples
- Molecular testing
A biopsy is the usual way to confirm a lung cancer diagnosis. A small sample of tissue is taken from the lung, the nearby lymph nodes, or both. The biopsy 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.
You will be given a local anaesthetic. Using a CT scan for guidance, the doctor inserts a needle through the chest wall to remove a small piece of tumour from the outer part of the lungs. You will be monitored for a few hours afterwards, as there is a small risk of damaging the lung. This can be treated if it does occur.
This allows the doctor to look inside the large airways (bronchi) using a bronchoscope, a flexible tube with a light and camera. You will be given either sedation or a light general anaesthetic, then the doctor will pass the bronchoscope into your nose or mouth, down the trachea (windpipe) and into the bronchi.
If the tumour is near the bronchi, samples of cells can be collected with a washing or brushing method. During “washing”, fluid is injected into the lung and then removed to be looked at under a microscope. “Brushing” uses a brush-like instrument to remove some cells from the bronchi. If the doctor sees a tumour, they will take a sample.
I think the doctors knew I had cancer based on the shadow on my CT scan. But they didn’t tell me right away. I had to wait two weeks until I had a bronchoscopy and wash.James
This is a type of bronchoscopy that allows the doctor to see a cancer deeper in the lung. It can also take samples of cells from a tumour or a lymph node in the middle of your chest or next to the airways, or from the outer parts of the lung.
You will have sedation or a general anaesthetic, and the doctor will put a bronchoscope with a small ultrasound probe on the end into your mouth. The ultrasound probe uses soundwaves to create pictures that show the size and position of a tumour. This allows the doctor to measure the tumour and take samples.
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.
This type of biopsy is not used often but may be done if a sample is needed from the lymph nodes found in the area between the lungs (mediastinum). 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 be monitored overnight in hospital.
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 take a tissue sample from the lungs. It is usually done under general anaesthetic with a type of keyhole surgery called video-assisted thoracoscopic surgery (VATS). Sometimes a simpler procedure called a medical thoracoscopy can be done as a day procedure. This is done when you are under sedation.
The doctor may take a sample of cells from the lymph nodes in the neck with a thin needle. This is often done using ultrasound for guidance.
In some circumstances, such as if you aren’t well enough for a biopsy, mucus or fluid from your lungs may be checked for abnormal cells.
This test examines a sample of mucus (sputum) from your lungs to see if there are any cancer cells. Sputum is different from saliva as it contains cells that line the airways. To collect a sample, you will be asked to cough deeply and forcefully into a container. This can be done in the morning at home. You can keep the sample in your fridge until you take it to your doctor, who will send it to a laboratory to check under a microscope.
A new test known as liquid biopsy involves taking a blood sample and examining it for cancer. Liquid biopsy is still being studied to see how accurate it is, and it is not a routine way to diagnose lung cancer.
Also known as pleurocentesis or thoracentesis, this procedure drains fluid from around the lungs. It can help to ease breathlessness, and the fluid can be tested for cancer cells. It is mostly done with a local anaesthetic, with the doctor using ultrasound to guide the procedure.
As with all biopsies, the results need to be interpreted along with the results of physical examination, blood and breathing tests, and imaging tests such as x-ray and CT scan.
The biopsy sample may be tested for genetic changes or specific proteins in the cancer cells (biomarkers). These tests are known as molecular tests and they help work out which drugs may work best in treating the cancer.
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 is not the same thing as genes inherited from your parents.
The most common genetic mutations seen in non-small cell lung cancer (NSCLC) are changes in the following genes:
- EGFR (epidermal growth factor receptor)
- ALK (anaplastic lymphoma kinase)
These three mutations can be treated with medicines known as targeted therapy.
Other mutations linked to NSCLC (such as KRAS) do not yet have a targeted therapy available to treat them.
The presence and amount of certain proteins found in the biopsy sample from a NSCLC may suggest the cancer will respond to immunotherapy. The most common protein tested for is called PD-L1.
A/Prof Nick Pavlakis, President, Australasian Lung Cancer Trials Group, President, Clinical Oncology Society of Australia, and Senior Staff Specialist, Department of Medical Oncology, Royal North Shore Hospital, NSW; Dr Naveed Alam, Thoracic Surgeon, St Vincent’s Private Hospital Melbourne, VIC; Prof Kwun Fong, Thoracic and Sleep Physician and Director, UQ Thoracic Research Centre, The Prince Charles Hospital, and Professor of Medicine, The University of Queensland, QLD; Renae Grundy, Clinical Nurse Consultant – Lung, Royal Hobart Hospital, TAS; A/Prof Brian Le, Director, Palliative Care, Victorian Comprehensive Cancer Centre – Peter MacCallum Cancer Centre and The Royal Melbourne Hospital, and The University Of Melbourne, VIC; A/Prof Margot Lehman, Senior Radiation Oncologist and Director, Radiation Oncology, Princess Alexandra Hospital, QLD; Susana Lloyd, Consumer; Caitriona Nienaber, 13 11 20 Consultant, Cancer Council WA; Nicole Parkinson, Lung Cancer Support Nurse, Lung Foundation Australia.
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