Mesothelioma symptoms do not appear until decades after the initial exposure to asbestos occurred. As a result, most mesothelioma diagnoses are not made until the disease has reached an advanced stage. An early diagnosis can provide patients with more treatment options.
Mesothelioma specialists use a variety of tests to help diagnose mesothelioma. Diagnostic tests help them obtain an accurate picture of the cancer stage and location of the mesothelioma tumor.
An accurate diagnosis can lead to more treatment options for the patient and, ultimately, a better chance for an improved prognosis. Because accurate diagnoses are so important, some patients choose to have a second opinion.
Types of Diagnostic Tests for Mesothelioma
Imaging scans. X-rays, CT scans, and MRIs are all common diagnostic tests for mesothelioma. The type of symptoms a patient experiences determines the type of scans a doctor uses to find the problem.
Biopsies. A biopsy is a tissue or fluid sample from someone who potentially has mesothelioma. After an imaging scan shows potential signs of cancer, doctors obtain a biopsy. This is the only way to confirm a diagnosis of mesothelioma.
Blood tests. People with mesothelioma have higher concentrations of certain proteins in their blood. Blood tests can help doctors make a more accurate diagnosis of how advanced the patient’s cancer is.
Imaging Tests: The First Step
An x-ray is the first diagnostic test a patient will encounter if their doctor believes their symptoms point to mesothelioma. It produces a two-dimensional scan of the affected area, showing tumors and buildups of fluid in the pleural or peritoneal cavities.
If the x-ray shows any indication of a tumor or a collection of fluid, the doctor will most likely order another test, like a CT scan, for a clearer picture of the problem area.
A computed tomography (CT) scan provides doctors with three-dimensional scans of the affected area. Specialists often use a CT scan as a follow up to an x-ray. They can use these detailed images to find diseased tissue suitable for a biopsy.
A magnetic resonance imaging (MRI) scan produces high-resolution images of bones and body tissues. The MRI is different than a CT scan because it can differentiate body tissues and assign them colors.
Chest MRIs help specialists determine if the mesothelioma has metastasized (spread) to the chest wall, diaphragm or other areas. Metastasis to these areas indicates an advanced stage of mesothelioma.
A Positron Emission Tomography (PET) scan can show how active a tumor has been over time. Specialists use a special fluid they administer to the patient via IV to trace the cellular activity of a tumor. The fluid is attracted to cancer cells and helps doctors locate small tumors that may not have otherwise been picked up by other diagnostic scans. Like an MRI, the PET scan can also help specialists determine if the cancer has metastasized to other parts of the body.
An echocardiogram uses sound waves to examine how well the heart is functioning. Patients with pericardial mesothelioma often experience chest pressure caused by a pericardial effusion, the buildup of fluid in the pericardium. Pressure from the pericardial effusion makes the heart work harder and beat irregularly. An echocardiogram can pick up on these symptoms and help diagnose pericardial mesothelioma.
Diagnostic specialists called pathologists need to collect samples from the tumor mass or fluid buildup they found via an imaging test to confirm a mesothelioma diagnosis. The procedure they use to collect these samples is called a biopsy. A biopsy can be surgical or non-surgical.
When a biopsy is collected, a pathologist runs various tests on the fluid and tissue samples to find definite signs, or markers, of cancer cells in the body. These signs are also used to confirm a tumor’s cell type.
A biopsy is the only definitive way to diagnose mesothelioma. Only an experienced specialist can accurately diagnose mesothelioma.
Thoracoscopy. A thoracoscopy is used to diagnose pleural mesothelioma. During this procedure, a surgeon makes a few small incisions in the patient's chest. Through these incisions, the surgeon inserts a camera and a device capable of retrieving a tissue sample from the pleural cavity. The small incisions used in a thoracoscopy are beneficial because it reduces a patient’s recovery time after the procedure is completed.
Thoracotomy. A thoracotomy is more invasive than a thoracoscopy. Surgeons make a large incision in the patient’s chest and take a direct sample from the chest cavity. This procedure doesn't require a camera. Doctors recommend a thoracotomy to get a better look into the pleural cavity. Invasive curative surgeries, such as the pleurectomy with decortication (P/D) and the extrapleural pneumonectomy (EPP), require a thoracotomy.
Mediastinoscopy. In a mediastinoscopy, doctors use a lighted camera attached to a small, thin tube to examine the area between the lungs (commonly called the mediastinum). This procedure may occur after an imaging test indicates the presence of a tumor in the suspected area. Since lymph nodes are present in the mediastinum, a mediastinoscopy helps determine if a patient’s mesothelioma is at an advanced stage and has spread outside of the pleura.
Laparotomy.The surgeon makes a cut into the abdomen while the patient is under general anesthesia. A direct sample of the mesothelioma is taken from the abdominal cavity for further testing.
Laparoscopy. A laparoscopy is less invasive than a laparotomy. The surgeon uses a camera to examine the abdominal cavity and collects tissue samples through small incisions in the abdomen. The laparoscopy requires a shorter amount of recovery time than a more invasive laparotomy.
Non-surgical biopsies are beneficial to patients because they do not require surgery and are often out-patient procedures.
Specialists perform a non-surgical biopsy by inserting a hollow needle into the affected area. They often use an imaging technology, such as an ultrasound or CT scan, to help guide the needle. After the needle reaches the affected area, fluid is drained and sent to a lab, where a pathologist examines it under a microscope.
The three types of non-surgical biopsies are:
- Thoracentesis. A needle is inserted into the chest cavity, from which fluid is drawn for testing.
- Paracentesis. The fluid is removed from the space between the inner and outer peritoneal linings.
- Pericardiocentesis. The fluid is removed from the pericardium, the lining of the heart.
Testing the Samples
Under a microscope, mesothelioma cells often very similar to other forms of cancer. Two types of cancer that mimic the cellular structure of mesothelioma are carcinomas and sarcomas.
Pathologists perform extra tests to help differentiate mesothelioma cells from other types of cancer. Histological tests are used to identify the presence of mesothelioma in tissue biopsies, while cytological tests are used to examine fluid biopsies.
Pathology tests also confirm the cell type of a mesothelioma tumor. A tumor’s cell type contributes to how responsive the cancer may be to treatment and to a patient’s overall life expectancy.
Some ways to test fluid and tissue samples include:
Immunohistochemistry. An immunohistochemical test uses ink staining to detect certain proteins in tissue cells. Mesothelioma cancer cells have proteins that other cancer cells do not. Specialists use these proteins, called immunomarkers, to distinguish mesothelioma cells from other cancer cells.
DNA microarray analysis. Cells from different cancers have distinct genetic patterns. A DNA microarray analysis helps specialists distinguish between these patterns, which leads to a more accurate diagnosis.
Electron microscopy. An electron microscope allows for a more detailed view of cancer cells than a traditional light microscope.
Blood tests measure the level of proteins and other signs pointing to the presence of mesothelioma. They provide doctors with a picture of how far mesothelioma has spread.
Mesothelioma patients typically exhibit higher concentrations of:
Osteopontin (OPN). Studies show that OPN plays a role in many biological processes, like the development of tumors. People with high OPN levels carry a higher likelihood of developing mesothelioma.
Cancer Antigen 125 (CA125). Patients diagnosed with mesothelioma show higher amounts of CA125 in their blood. Doctors do not know the exact role the antigen plays in the development of mesothelioma, but it could be an important marker used for earlier diagnosis.
Fibulin-3. Patients diagnosed with mesothelioma also show higher concentrations of Fibulin-3. As with CA125, doctors know little about the role played by Fibulin-3 in the development of mesothelioma, but are currently testing its significance in the development of mesothelioma.
MesoMark™. MesoMark™ is a test that can accurately diagnose mesothelioma by measuring the amount of soluble mesothelin-related peptides (SMRP) in a patient’s blood. SMRPs are biomarkers, or signs, of mesothelioma.
Understanding Your Diagnosis
Once a mesothelioma diagnosis is confirmed, a specialist will create a course of treatment tailored to the patient’s diagnosis. After a complete diagnosis, you will know the cell type, stage, and location of the tumor. Each of these factors play an important role in a your treatment options and prognosis.
No matter your diagnosis, however, their are treatment options available that can extend your life.
Patients with advanced stage mesothelioma may not be eligible for aggressive surgery due to the far spread of the disease, but still have options. Clinical trials can offer patients of all stages innovative treatments that can make a difference in their prognosis.
Regardless of a patient’s mesothelioma stage, getting treatment is the next, and most important, step. The right course of treatment can extend life expectancy and improve a patient’s quality of life.
If you’ve been diagnosed with mesothelioma, you can learn more your treatment options in our free informational guide.