biopsies involve collection of small tissue samples for examination in order to determine the presence and type of lung cancer in an individual.
At present, tissue biopsies represent the only method for confirming accurately lung cancer.
(Liquid biopsies, conducted on blood samples, are performed in other cases. Read more in the Biomarker Testing section.)
There are various techniques employed by doctors to obtain tissue samples. Depending on the chosen method, it is possible for the doctor to assess whether the cancer has metastasized to lymph nodes or other organs. The excised tissue is forwarded to a pathologist for examination, who subsequently issues a pathology report.
It is also crucial to consider the availability of sufficient tissue for biomarker testing (mutation, genomic, or molecular). Prior to undergoing a biopsy, patients should discuss with their doctor the possibility of having molecular profiling.
Bronchoscopy
A bronchoscopy, performed by a surgeon or a chest physician, involves the insertion of a bronchoscope – a thin, flexible tube – through the patient’s mouth or nose, travelling down the trachea and into the lungs. Equipped with a light and a camera at its tip, the bronchoscope enables the doctor to visually inspect for any abnormal areas. Additionally, miniature tools can be maneuvered through the bronchoscope’s lumen to obtain tissue samples, which are subsequently examined under a microscope for cancer cells.
Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA)
These are bronchoscopes equipped with an ultrasound device at their tip which allow the evaluation of lesions around the bronchi, such as lymph nodes and vessels. Endobronchial ultrasound examination and needle biopsy (EBUS -TBNA) is nowadays essential in nearly every case screened for lung cancer in order to establish the diagnosis and stage of the disease.
Bronchoscopy is generally a painless procedure and is always performed with local anaesthesia and intravenous sedation of patients.
Transthoracic needle biopsy (Fine Needle Aspiration – FNA)
If there’s a suspicious mass on the outer edge of the lungs, a needle can be carefully guided through the chest wall using either CT or ultrasound to take a tissue sample or aspirate suspicious fluid. When a small needle is inserted through the skin of the chest wall, it’s known as a fine needle aspiration (FNA). For larger samples, a core biopsy is performed with a larger needle.
During a transthoracic needle biopsy, an interventional radiologist inserts a needle through the chest wall. A chest CT scan or a special X-ray machine called a fluoroscope helps guide the needle toward the suspicious area. A sample of the mass is then withdrawn and sent to the lab to check for cancer cells.
This type of biopsy has the advantage of requiring only a small skin incision, often requiring only local anaesthetic. However, there are drawbacks, such as the possibility of missing small nodules or failing to provide enough samples for a diagnosis or biomarker testing. Note: Core biopsy is usually preferred for biomarker testing.
There is also a minor risk of air leaking out of the lung at the biopsy site, causing a complication called pneumothorax. This can result in difficulty breathing due to lung collapse. Treatment for pneumothorax may involve the insertion of a chest tube or aspirate the air with a needle.
Thoracentesis
In the case of a pleural effusion (fluid in the cavity where the lung resides), physicians may conduct a thoracentesis to investigate whether it stems from cancer spreading to the lung lining. During this procedure, the doctor administers local anesthesia before inserting a needle, between the ribs, to extract the fluid. The fluid is subsequently examined for cancer cells.
Thoracoscopy/VATS
A thoracoscopy, also known as video-assisted thoracoscopic surgery (VATS), is a surgical procedure conducted in an operating room under general anesthesia. During this procedure, a surgeon makes a small incision in the chest wall and inserts a specialized instrument equipped with a tiny video camera to examine the lungs and the interior of the chest. Tissue samples are collected for examination by a pathologist under a microscope.
The thoracoscopy serves various purposes, such as:
- Obtain samples from tumors and lymph nodes located on the outer regions of the lungs.
- Assess for lung cancer metastases in the spaces between the lungs and the chest wall.
- Determin if the tumor has spread to nearby lymph nodes and other organs.
- Provide treatment by removing part of the lung in certain cases with early-stage lung cancer.
As it is a more invasive procedure, requiring general anesthesia, thoracoscopy is typically not the initial diagnostic procedure for obtaining tissue to diagnose lung cancer unless less invasive methods are unsuccessful. However, it is frequently performed during the treatment phase of lung cancer.
Mediastinoscopy and mediastinotomy
Mediastinoscopy is a procedure aimed at obtaining tissue from the mediastinum. A small incision is made at the top of the breastbone, located in the front of the neck. Subsequently, a thin, hollow tube containing a light and a viewing lens is inserted through this incision. Instruments are then passed through the tube to obtain samples from the lymph nodes positioned alongside the trachea. These samples are forwarded to a laboratory for examination to examine for cancer cells. Mediastinoscopy is conducted under general anesthesia in an operating room. It is an easy procedure to perform and does not require any hospital stay.
Similarly, mediastinotomy is another procedure used to obtain tissue from lymph glands. This procedure is undertaken through a slightly larger incision compared to mediastinoscopy, positioned near the breastbone and between the left second and third ribs. This incision allows access to lymph nodes that may be inaccessible via mediastinoscopy.
We should however note that both procedures are rarely performed nowadays as they have been replaced by EBUS TBNA.
Source: Biopsies | LUNGevity Foundation
