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 if it is lung cancer.
Learn more about:
- PET–CT scan
- Other tests
- Molecular testing
- Further tests
This scan combines a PET (positron emission tomography) scan with a CT scan in one machine. As well as helping with diagnosis, a PET–CT scan can provide detailed information about any cancer that is found.
First, a small amount of radioactive glucose solution is injected into a vein, usually in your arm. You will be asked to sit 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.
I had a PET scan and they could tell that the cancer was only in the right lung and one lymph node nearby.JUDY
The most common way to confirm a lung cancer diagnosis is by biopsy. A small sample of tissue is taken from the lung, the nearby 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.
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 does occur.
The doctor will look inside the large airways (bronchi) using a bronchoscope, a flexible tube with a light and camera. A bronchosopy is usually performed under light sedation, so you will be awake but feel relaxed and drowsy. You will 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.
If the tumour is near the bronchi, samples of cells can be collected using either 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 possible, the doctor will use small forceps to take a tissue sample for biopsy.
This is a type of bronchoscopy that allows the doctor to see a cancer deeper in the lung. 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 of your chest 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 bronchi.
The ultrasound probe uses soundwaves to create pictures that show the size and position of a tumour.
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 passed into your mouth and down your oesophagus and a cell sample is taken from the lymph nodes.
This type of biopsy is not used often but 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.
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, because only light sedation is needed.
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.
If there is concern that the cancer may have spread to other organs, such as the brain, different types of biopsies may be done.
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.
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.
In this test, a sample of mucus from your lungs (called sputum or phlegm) is examined to see if there are 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 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.
Also known as pleurocentesis or thoracentesis, this procedure drains fluid from around the lungs. A pleural tap 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.
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 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 (acquired mutation) is not the same thing as genes inherited from your parents. Most gene changes linked to lung cancer are not inherited.
In NSCLC, the most common genetic mutations are changes in the EGFR (epidermal growth factor receptor), ALK (anaplastic lymphoma kinase), ROS1 (ROS proto-oncogene 1), and KRAS (Kirsten rat sarcoma virus) genes. Lung cancers with these gene mutations can be treated with a type of medicine called targeted therapy.
If certain proteins are found in the biopsy sample from a NSCLC, the cancer may respond to immunotherapy. The most common protein tested for is called PD-L1 (programmed death ligand-1).
If the tests described in this section 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. 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) or a bone scan. For more information, talk to your doctor or call Cancer Council 13 11 20.
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
Podcast: Tests and Cancer
A/Prof Brett Hughes, Senior Staff Specialist Medical Oncologist, Royal Brisbane and Women’s Hospital, The Prince Charles Hospital and The University of Queensland, QLD; Dr Brendan Dougherty, Respiratory and Sleep Medicine Specialist, Flinders Medical Centre, SA; Kim Greco, Nurse Consultant – Lung Cancer, Flinders Medical Centre, SA; Dr Susan Harden, Radiation Oncologist, Peter MacCallum Cancer Centre, VIC; A/Prof Rohit Joshi, Medical Oncologist, GenesisCare and Lyell McEwin Hospital, Director, Cancer Research SA; Kathlene Robson, 13 11 20 Consultant, Cancer Council ACT; Peter Spolc, Consumer; Nicole Taylor, Lung Cancer and Mesothelioma Cancer Specialist Nurse, Canberra Hospital, ACT; Rosemary Taylor, Consumer; A/Prof Gavin M Wright, Director of Surgical Oncology, St Vincent’s Hospital and Research and Education Lead – Lung Cancer, Victorian Comprehensive Cancer Centre, VIC.
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