How Are Biopsies Performed, and Which Biopsy Is Best for Me?
If preliminary tests show that you have abnormal growth in your chest or abdomen, and if blood tests show the presence of tumor markers such as mesothelin, your doctor will probably do a biopsy. A biopsy is when a radiologist, doctor, or surgeon removes some fluid or a piece of tissue in order to look at it under the microscope and to determine whether cancer cells are present. While the tests performed on the biopsied cells are similar for every biopsy, there are many different ways of removing cells. Some of these methods are so simple and noninvasive that you can do them on an outpatient basis and without general anesthesia, while others are major surgeries that require anesthesia and hospitalization. Especially considering that biopsies are only diagnostic tests and are not cancer treatments in themselves, it is important for doctors to choose the least invasive kind of biopsy that will enable them to reach the tumor or abnormal fluid buildup.
It Is Almost Impossible to Diagnose Mesothelioma Without a Biopsy
A biopsy is never the only test that a patient undergoes before receiving a diagnosis of mesothelioma. Before you get a biopsy, there are several other tests. Almost every patient who gets mesothelioma has done a chest X-ray, which shows whether there are abnormal masses or abnormal fluid buildup in the chest. A chest X-ray can tell you that something is wrong, but if doctors were to make decisions about how to approach the target tissues for a biopsy based solely on a chest X-ray, especially since X-rays can only provide a two-dimensional image. If doctors only used the chest X-ray as a guide for how to do the biopsy, they could end up causing a lot of preventable and unnecessary injuries to healthy tissues.
Therefore, doctors often order additional imaging tests after the chest X-ray and before the tissue biopsy. The most common types of these tests are computerized tomography (CT) scans, magnetic resonance imaging (MRI), and positron emission tomography (PET) scans. These tests enable doctors to see the internal tissues and structures of the body in much more detail. CT scans and PET scans are more common in patients suspected of having mesothelioma, especially if the mesothelioma is in its early stages since MRIs are better at visualizing the brain and the insides of bones and joints, which are not where mesothelioma begins. PET scans are especially helpful because they make tumors and other inflamed tissues appear brighter than healthy tissues. Before the biopsy, your doctor may also do blood tests to check for certain tumor markers, and if the tumor markers, also known as biomarkers, are especially elevated, this could indicate that cancer has spread, and therefore the doctors may want to do imaging tests of other parts of the body, too.
Imaging tests can tell doctors where the abnormal growth is that they should biopsy. Blood tests for tumor markers can give clues about what kind of cancer it is, but they cannot make a clear diagnosis. For example, prostate-specific antigen (PSA) is a biomarker that can indicate prostate cancer, but it can also indicate other, non-cancerous diseases of the prostate gland. Likewise, the biomarker mesothelin can indicate mesothelioma, as well as lung cancer and ovarian cancer.
After your doctors have done enough imaging tests so that they can be sure of the location of the abnormal growth, they will choose a strategy for taking a biopsy. They will choose the least invasive method that allows them to take enough cells to be sure of their diagnosis. It is only when they remove cells from the abnormal growth that they saw on the image and look at those cells under a microscope that they can be sure whether you have mesothelioma, another type of cancer, or just a non-cancerous tumor.
Thoracentesis and Paracentesis
The least invasive biopsy procedures for mesothelioma screening are thoracentesis and paracentesis. Thoracentesis involves withdrawing a small amount of built-up fluid from the chest cavity with a needle, and paracentesis is a similar procedure performed on the built-up fluid in the abdominal cavity. The “centesis” part of the names of the procedures refers to sticking something with a needle. For example, you may have heard of a procedure called amniocentesis that is performed during pregnancy to diagnose certain conditions in the unborn baby. (The only reason amniocentesis is performed less commonly today than it was in previous decades is that less invasive tests have been developed that can provide the same diagnostic information.) Thoracentesis and paracentesis do not require general anesthesia; instead, doctors apply a local anesthetic before inserting the needle, much like the topical and injected local anesthetics that dentists use for procedures such as removing carious lesions from the teeth.
It is only useful, and in fact, only possible, to perform thoracentesis or paracentesis if there is fluid buildup in the chest or abdomen. If the fluid is in the chest, this is usually diagnosed with a chest X-ray. Thoracentesis is only possible if the fluid is not walled off by scar tissue; when this happens, the fluid is said to be loculated. If the fluid is loculated, a more invasive procedure is necessary to get a fluid sample for biopsy.
Possible Complications of Thoracentesis
Obtaining fluid to test for cancer cells is only one of the purposes of thoracentesis. The other purpose is to remove as much excess fluid as possible. An abnormal buildup of fluid in the chest is very uncomfortable and makes it difficult for the lungs to expand, leading to shortness of breath. Successful removal of the fluid can make it much easier to breathe. After the thoracentesis, the doctor will perform a chest X-ray to check whether they have removed all the excess fluid. This X-ray can also show whether you have developed complications from the procedure, such as hemothorax (bleeding in the chest cavity) or pneumothorax (air in the chest cavity).
When Testing Fluid for the Presence of Cancer Cells Is Not Enough
It is certainly alarming to find out that fluid that was drawn from your chest or abdomen contains cancer cells, but unfortunately, it does not enable doctors to choose a treatment strategy. Cancer does not originate in built-up fluid in a person’s chest or abdomen; those cancer cells have been shed from a tumor somewhere else in the body. If there are cancerous cells in your thoracentesis or paracentesis fluid, you will need more imaging tests, and perhaps more biopsies, to determine the location of tumors and the staging of cancer.
Thoracoscopy and Peritoneoscopy
If it is not possible to do a thoracentesis, or if the biopsy results after a thoracentesis are inconclusive, your doctor will do a thoracoscopy. This procedure is done under general anesthesia, but you can usually do it at an outpatient surgery center. The surgeon will make a small surgical incision and insert a periscope-like tube with a light attached to it. As the surgeon explores your chest cavity (in the case of thoracoscopy) or abdominal cavity (in the case of peritoneoscopy), they will look for abnormal growths and remove tissue samples from them for biopsy. An advantage of thoracoscopy and peritoneoscopy is that they allow doctors to see the size and location of tumors more accurately than they can with CT scans and PET scans; this can help them make important decisions about treatment. Another advantage is that they can take several biopsy samples from different locations during the same surgery.
Open Surgery for Tissue Biopsy
If the tumor is very solid or is in a location that is not accessible by thoracoscopy, your doctor may refer you to a cancer surgeon to perform an open biopsy. You must be hospitalized for this procedure, and your doctor will give you pain medication while you recover from it. The surgeon makes an incision about three inches long and removes a small section of a rib in order to reach the tumor. Then the surgeon takes a tissue sample that is the size of a dime, or even bigger, to examine it for biopsy. During this procedure, the surgeon can see the size and location of the tumor, and this can help the surgeon identify the best way to surgically remove the tumor if it turns out to be cancerous.
Testing the Biopsied Tissues to Diagnose or Rule Out Mesothelioma
Whether the cells being tested came from fluid or from surgically removed solid tissue, cytologists and pathologists will look at it under a microscope under high magnification. They will apply dyes and stains to the sample to enable them to see the cells in more detail. Not only dies the biopsy tell you whether you have cancer, it tells you what type of cancer it is. If the cancer is mesothelioma, the appearance of the biopsied cells can tell you what kind of mesothelioma it is. The main types of mesothelioma are epithelioid, sarcomatoid, and biphasic; the biphasic type of mesothelioma is characterized by tumors that contain both epithelioid cells and sarcomatoid cells. After you have received a mesothelioma diagnosis through the biopsy results, the next steps are more tests to determine how far the disease has progressed, and then you can begin with treatment.