Lung cancer diagnosis has gone from major surgery to day procedure thanks to medical ingenuity
Collecting samples to diagnose most lung cancers used to require a major operation called a thoracotomy followed by about 10 days in hospital to recover. Now it’s a minimally invasive day procedure. Adjunct Professor Andrew Field talked us through this quiet but important revolution for lung cancer patients.
“We have been able to obtain sputum and bronchial washings, where cells are taken from the inside of the airways through a flexible tube called a bronchoscope, for a long time. But it is more difficult to access lesions that aren’t inside the bronchi (air passages to and within the lungs), especially when they’re in the central part of the chest,” he explained.
The difficulty is mostly due to this location. The lungs are not only formidably protected by the rib cage (also known as the thoracic cage), but they are geographically close to the heart and great vessels as well.
“The only way to access the lungs in the past was for the patient to have a thoracotomy. This involves a surgeon cutting through the chest wall and spreading the ribs to reach the lungs. It is a major operation, and sometimes it wasn’t of great benefit to the patient if we then found in many cases that they had inoperable lung cancer, especially when there were fewer treatment options available,” A/Prof Field explained.
There had to be a better way.
“Fine needle aspiration (FNA) biopsy cytology was pioneered in Scandinavia, particularly at the Karolinska and Malmo Hospitals and in New York, in the late 1950s and 1960s. It was then put into practice in Australia and New Zealand from the late 1960s. A Swedish cytopathologist named Svante Orell, who had emigrated from Stockholm to Australia, was one of the main drivers and teachers in this development,” said A/Prof Field.
“FNA involves inserting a very fine needle - smaller than those used to draw blood from a vein - directly through the skin into any lesion that can be palpated or seen on an ultrasound. These needles can also be guided through the skin and chest wall into the lung via a CT scan,” he explained.
“Once the needle reaches the nodule in the lung, the needle collects the cells which can be aspirated or sucked up through it and then pushed out and smeared onto glass slides. These are stained and examined by a specialist cytopathologist who then determines if the patient has cancer. The cells can also be clotted together in a cell block for further highly sophisticated immunohistochemical and molecular testing to decide on ‘magic bullet’ treatment.”
A/Prof Field said FNA cytology through the chest wall was a huge step forward because it was a less invasive procedure than a thoracotomy, but it has potential complications such as allowing air into the pleural cavity which is a dangerous situation called pneumothorax. It is also not an option for tumours deep in the central chest.
There had to be an even better way.
“Endobronchial Ultrasound Bronchoscopy (EBUS) was introduced in the late 1990s. This is a flexible scope with a camera on the end that is inserted through the mouth and down the major airways into the lungs. It enables us to see the lining of the airways. There is also a small ultrasound probe at the end of the scope. The probe can be placed against the bronchial wall to see lesions in the lung and lymph nodes next to the bronchi. The bronchoscopist can then take a biopsy of anything that looks like a cancer in the lung, or of anything suspicious in the lymph glands, using a needle that is introduced down the scope and into the tip of the bronchoscope. It is then passed through the wall of the bronchus to perform a transbronchial fine needle aspiration biopsy (TBNA),” said A/Prof Field.
He said cytopathologists or cytotechnologists are present in the endoscopy room during the EBUS procedure. They perform a rapid onsite evaluation (ROSE) of the material on the slides to make sure enough material is collected, and to prepare the material for all of the specialised tests.
“Further analysis also happens at the laboratory where all the cytology slides of the lung cancer itself and the lymph nodes, which are all individually biopsied, are viewed by the cytopathologist. If lung cancer is diagnosed then a cell block fixed in formalin and embedded in paraffin can be used to further type the lung cancer and to then perform molecular testing for gene mutations that will inform treatment decisions.
“If there are not enough cells collected to make the cell block, then the pathology department at St Vincent’s Hospital uses a new technique to scrape the cells off the cytology slides, and these are then used for the molecular testing. In many cases, these scraped cells provide better DNA for this purpose because they are whole cells smeared on the glass slides.”
A/Prof Field said if the cancer has spread to the sampled lymph nodes this changes the ‘stage’ of the cancer, and will guide the clinicians to go ahead with surgery, or if the cancer has spread too far, to use radiotherapy and chemotherapy alone. If the pathology testing shows the cancer has one of the newly discovered specific molecular changes, then one of the new specific drugs can be used in the treatment.
Thoracotomy and removal of a lung cancer can be curative in lung cancers that have not spread, but A/Prof Field said FNA directed by EBUS allows most patients to receive their initial diagnosis without having to undergo a thoracotomy.
Diagnosing and staging lung cancer from one minimally invasive EBUS day-only procedure is certainly a far cry from using a thoracotomy to obtain the same information. When it’s teamed with genomics, targeted therapies and immunotherapy, lung cancer patients are certainly benefiting from rapid diagnosis informing better treatment options, and from the determination to always find a better way.
A/Prof Field is a specialist cytopathologist at St Vincent’s Hospital Sydney, President-elect of the International Academy of Cytology, and Adjunct Professor at Notre Dame University Medical School in Sydney.
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This article appeared in the August 2017 Edition of ePathWay which is an online magazine produced by the Royal College of Pathologists of Australasia (http://www.rcpa.edu.au/Library/Publications/ePathway).
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