How Do Doctors Diagnose Malignant Mesothelioma?
Mesothelioma is a rare cancer that is often difficult to diagnose. The disease is a result of exposure to asbestos, a toxic material that was heavily used in the United States for nearly five decades.
In the majority of patients, mesothelioma doesn’t develop for decades after asbestos exposure. The disease has a long latency period (or time from the initial exposure to the development and discovery of cancer). During the early stages of the disease, patients may not notice any symptoms. Or they may experience symptoms similar to those of other common conditions, like the flu.
Patients with chronic chest or stomach pain, trouble breathing or a persistent cough could be exhibiting symptoms of mesothelioma. If you are experiencing the symptoms of mesothelioma and there’s a chance you encountered to asbestos in the past, it’s essential to contact a medical professional immediately. An early mesothelioma diagnosis often leads to a better prognosis. This cancer is aggressive, and people who discover it early may live longer and enjoy a better quality of life.
The Diagnostic Process
A combination of imaging tests, blood samples, and biopsies are required to diagnose mesothelioma. Your doctor will also perform a physical exam.
Common Diagnostic Tests: Imaging
Doctors usually begin the mesothelioma diagnostic process with a series of imaging tests, starting with lower resolution scans and moving to higher resolution tests when necessary.
- The most basic imaging test, an X-ray, is a low-resolution scan that offers a two-dimensional view of the body. X-rays will pick up abnormalities in the body that may indicate the presence of mesothelioma. These include tumors, thickening of the lining of the abdominal and chest cavities, or excess fluid around the organs. Abnormal scans will likely lead to additional, higher resolution imaging tests. On average, an X-ray takes 15 minutes.
- CT Scan
- Computed tomography scans, otherwise known as CAT or CT scans, utilize a combination of rotating X-rays and computer images to access different angles of the body. CT scans allow doctors to pinpoint the location or size of any abnormalities, which is particularly helpful during a cancer diagnosis. This imaging scan usually takes about 30 minutes.
- PET Scan
- When doctors need an even more detailed, three-dimensional view, they’ll order a positron emission tomography scan, or PET scan. This imaging test involves injecting patients with a small dose of a radiotracer, or contrast material. This dye temporarily interacts with the affected organs or tissues, highlighting irregularities at a cellular level. PET scans help doctors determine the stage of the cancer based on how far the disease has spread. Once injected, it will take the radiotracer about 60 minutes to absorb into the affected sections of the body. The scan itself takes an additional 30 to 60 minutes.
- Magnetic resonance images, or MRIs, utilize a computer and strong magnetic field to produce a high-quality, three-dimensional image of the body. MRIs help doctors locate areas of the body that may require a biopsy. Like PET scans, MRIs are often used to determine how far the cancer has spread. Patients lay on a flat table that moves slowly in and out of a large magnetic tube. The machine can trigger anxiety in those who are claustrophobic. In these cases, a doctor may prescribe anti-anxiety medication. This scan may take up to an hour.
Common Diagnostic Tests: Blood Tests
A mesothelioma diagnosis is a long and often challenging process. Imaging tests are the first step, and blood tests are usually next in line. Common blood tests include:
- CANCER ANTIGEN (CA 125)
- Large concentrations of cancer cells contain a protein biomarker known as cancer antigen 125, or CA 125. Doctors use the CA 125 test to measure levels of this protein in a patient’s blood. It helps diagnose mesothelioma and may also help determine how well the cancer responds to chemotherapy.
- Another common biomarker in diagnosing mesothelioma is called fibulin-3. If a patient has high levels of this protein in their blood, it likely means they have mesothelioma, as opposed to another lung disease. Similar to CA 125, fibulin-3 helps doctors determine how a patient will respond to treatment.
- The FDA approved MesoMark® in 2007, making it the first blood test used specifically in diagnosing mesothelioma. Dead cells release mesothelin-related proteins, which MesoMark® measures, allowing doctors to assess the severity of the disease. There are limitations with this blood test, since sarcomatoid tumors (which occur in 25 percent of mesothelioma cases) don’t release the same mesothelin-based proteins. Doctors will often use MesoMark® in combination with other blood tests to ensure an accurate diagnosis.
Common Diagnostic Tests: Biopsies
A biopsy remains the only definitive way to diagnose mesothelioma. The procedure involves removing samples of fluid or tissue to determine whether the cancer has spread. Of the two, fluid biopsies are the least invasive, but because mesothelioma often resembles other diseases, a tissue biopsy is necessary for a conclusive diagnosis. Patients who are considering taking legal action against an asbestos company should get a tissue biopsy. The most common biopsies are needle biopsies, surgical biopsies, and camera-assisted biopsies.
The least invasive option for diagnosing mesothelioma, needle biopsies are often referred to as “closed biopsies.” In most cases, these are outpatient procedures.
- Thoracentesis is the most common needle biopsy. Doctors use a large needle to collect a sample of the patient’s pleural (lung) fluid to determine the presence and scope of the disease. Thoracentesis is performed on patients who are experiencing fluid buildup between their lungs and chest cavities, a condition called pleural effusion. Before collecting or draining fluid, the doctor will numb the area with an anesthetic. This procedure usually takes about 30 minutes, but it can last up to an hour.
- Paracentesis is performed the same way as a pleural biopsy but is used to test ascitic fluid, which can build up in the abdomen of patients with peritoneal mesothelioma. Doctors will numb the area, then insert a needle to remove excess fluid and relieve discomfort. A small sample of the ascitic fluid is then tested for the disease. This procedure lasts around 30 minutes.
- Patients with pericardial mesothelioma may experience fluid buildup around the heart sac. Pericardiocentesis involves draining fluid from the heart cavity. This procedure is similar to thoracentesis and paracentesis and can help in both diagnosing mesothelioma and relieving pain. Pericardiocentesis can take anywhere from 20 minutes to an hour.
Doctors will suggest camera-assisted biopsies after needle biopsies. These procedures involve a computer, surgical instruments, and a small camera.
- A thoracoscopy is a procedure that uses a viewing tube and camera, allowing a surgeon to see directly into the chest cavity. During this biopsy, a small incision is made in the patient’s chest to insert the viewing tube. Doctors use this camera-assisted biopsy to capture a small fluid sample and drain any excess fluid to help make the patient more comfortable. A thoracoscopy is a minimally invasive procedure and can take up to 90 minutes to complete.
- A laparoscopy procedure (also known as a “peritoneoscopy”) is similar to thoracoscopy but involves the abdomen. Doctors use a similar viewing tube and camera to take diagnostic samples and view organs that might be affected. A laparoscopy usually takes about 75 minutes to complete.
- A mediastinoscopy lets doctors examine the lymph nodes to see if the mesothelioma has spread. This procedure generally takes about 60 to 90 minutes.
Surgical biopsies are used as the last resort when minimally invasive biopsies haven’t provided conclusive results. These are performed under general anesthesia.
- If other tests have detected a tumor in the chest, a surgeon may perform a thoracotomy. During a thoracotomy, the surgeon will make an incision in the chest to take a sample of the affected tissue. If possible, they will attempt to remove the remainder of the tumor at the same time.
- A laparotomy is performed to take diagnostic samples and remove tumors found in the abdomen. It is also done under general anesthesia. During a laparotomy, the surgeon will make an incision in the patient’s stomach, examine a specific tissue sample, and then remove as much of the tumor as possible.