Mesothelioma is difficult to diagnose for many reasons. Currently, only a biopsy can definitively confirm mesothelioma.
Nonspecific symptoms and a long latency period make a proper diagnosis difficult.
Mesothelioma is often misdiagnosed as other common illnesses.
A biopsy is currently the only method to confirm a mesothelioma diagnosis.
Prognosis and treatment options will depend on the specifics of the diagnosis.
Mesothelioma is Difficult to Diagnose
Unfortunately, diagnosing mesothelioma takes a long time. While mesothelioma is widely talked about and publicized, it is still a rare condition. Even if patients have symptoms of mesothelioma, it may take several visits to a primary care physician for mesothelioma to be suspected. Several issues delay mesothelioma diagnosis, including nonspecific symptoms and a long latency period.
Mesothelioma has a poor prognosis for most patients by the time it is diagnosed. Because of this, early diagnosis of mesothelioma is paramount. If you or a loved one has a history of exposure to asbestos, it is best to monitor your health closely. Determining a mesothelioma diagnosis early means that patients will typically be in better health, the cancer will be localized, and the options for more aggressive treatments will be available.
Because early detection of the cancer is so important, recent studies of mesothelioma have focused on discovering more accurate diagnostic tools and procedures, like mesothelioma biomarkers and blood tests, that can detect the presence of mesothelioma earlier in the diagnosis process.
How is Mesothelioma Diagnosed?
Mesothelioma diagnosis can be challenging for patients and physicians alike. The diagnostic workup for mesothelioma is different for every patient, but usually includes a detailed medical history and physical examination, several imaging scans, blood tests, and biopsies.
Mesothelioma Diagnostic Tests
Mesothelioma is diagnosed using three types of tests: imaging scans, blood tests, and tissue biopsies. Doctors will typically start with imaging scans, as they are the least invasive, and follow up with additional tests if they are warranted and if a patient is healthy enough for more invasive procedures.
A standard diagnostic workup for mesothelioma includes some sort of imaging of the affected area, such as the chest, abdomen, or heart. Unfortunately, imaging studies cannot definitively diagnose mesothelioma by themselves. Nonetheless, imaging studies provide critical information that may help physicians make or rule out the diagnosis of mesothelioma, determine the stage of the cancer, and make future diagnostic and treatment decisions.
X-ray of the chest or abdomen is usually the first imaging study, but it does not provide enough information to diagnose mesothelioma. Nevertheless, an x-ray is important for finding early signs of mesothelioma, like fluid in the lungs. Moreover, an abnormal chest x-ray is usually followed by another imaging study, such as a CT scan.
A computerized tomography (CT) scan takes a series of x-ray images to create a detailed 3D image, allowing tumors to be discovered easily. A CT scan is approximately 90% sensitive for detecting malignant pleural mesothelioma.
Magnetic resonance imaging (MRI) uses powerful magnets to create high-resolution 3D images of the patient’s internal anatomy. The detailed images of an MRI can be useful for planning a biopsy or surgical removal of the mesothelioma tumor.
Positron emission tomography (PET) is a nuclear medicine imaging technique. PET is excellent at identifying cancer and distinguishing between malignant and benign disease.
Biomarkers and Blood Tests
Mesothelioma, like all cancers, produces substances that are not normally found in the bloodstream. Ideally, a physician could test for these substances in a patient’s blood and be able to diagnose or rule out mesothelioma without a biopsy or surgery. While several promised mesothelioma biomarkers exist, none is yet able to definitively diagnose mesothelioma. Nevertheless, biomarker tests, also known as “assays,” may provide useful information and could be part of a mesothelioma diagnostic workup.
The Mesomark assay is a blood test that detects fragments of mesothelin, a substance produced in large amounts by malignant mesothelioma. More specifically, the mesothelin fragments are called soluble mesothelin-related peptides, or SMRPs. The sensitivity of the Mesomark assay is low, so the test is not used to diagnose mesothelioma without other testing.
Similar to the SMRPs found during the Mesomark test, N-ERC/Mesothelin is another protein that can be found in the bloodstream when a patient is suffering from mesothelioma. Testing for N-ERC/Mesothelin shows a 95% sensitivity for the assay, making the test more accurate than the Mesomark and one of the most accurate blood tests available for mesothelioma.
Osteopontin is another molecule that accumulates in various types of cancer, including mesothelioma. Unfortunately, osteopontin levels in the blood can also increase during any serious illness, after stroke, by many other cancers, so it, like the Mesomark assay, cannot be used to diagnose mesothelioma without other tests.
Like mesothelin and osteopontin, blood levels of fibulin-3 are abnormally elevated in people with pleural mesothelioma and may be used with other testing to diagnose malignant mesothelioma. Fibulin-3 is also particularly good at distinguishing between cancer and benign lung diseases. Once malignant mesothelioma has been diagnosed, periodic fibulin-3 blood tests can be used to track the success of treatment.
Recent clinical trials have shown that testing for the HMGB1 protein – high mobility group box protein 1 – can reveal a mesothelioma diagnosis in patients. The presence of HMGB1 can also identify patients who have been exposed to asbestos but have not yet developed mesothelioma.
Currently, a biopsy procedure is the only definitive way to diagnose mesothelioma in patients exhibiting symptoms and with a history of asbestos exposure. The intention of a biopsy is to collect a sample of cancerous tissue to be examined under a microscope. The examination of the tissue will determine if the tumor is mesothelioma or another cancer. A biopsy can also indicate the stage of the disease and help determine the course of treatment. Some biopsy techniques are minimally invasive while others are a major surgical procedure.
During a needle biopsy, a needle is used to remove cells, fluid, and/or a fragment of tissue. Since there is no incision or general anesthesia, needle extraction biopsies are the least invasive way to obtain cells for analysis. Unfortunately, needle biopsies often do not collect enough tissue to accurately diagnosis a patient.
Types of needle biopsies:
Considered a minimally invasive surgery, camera-assisted biopsies allow doctors to use a small tube with a camera in it to collect sample tissue from the tumor.
Types of camera-assisted biopsies:
For some patients, a needle or camera-assisted biopsy may not be an option because of their tumor location. There are surgical biopsy options available for such situations.
Types of surgical biopsies:
Mesothelioma Is Often Misdiagnosed
Mesothelioma is often misdiagnosed because it is so rare, is related to asbestos exposure that may be decades in the past, and can cause symptoms that mimic so many other diseases. Due to these factors, mesothelioma may be misdiagnosed as some other lung or abdominal disease.
Examples of diseases that may be confused with types of mesothelioma:
- Chronic Obstructive Pulmonary Disease (COPD)
- Ovarian Cancer
- Crohn’s Disease
- Irritable Bowel Syndrome (IBS)
- Constrictive pericarditis
- Coronary artery disease
- Heart failure
- Tuberculosis pericarditis
- Pericardial synovial sarcoma
What Happens After Diagnosis?
Once a diagnosis of mesothelioma is made, each patient should be treated by one or more physicians who specialize in the treatment of mesothelioma. These may include a medical oncologist, surgical oncologist, thoracic surgeon, and a pulmonologist.
Most patients with mesothelioma undergo multimodality or trimodality therapy, which includes surgery, chemotherapy, and radiation therapy, in some order. Patients who have been diagnosed with mesothelioma should consider participating in a clinical trial. These clinical trials are designed to provide standard mesothelioma treatment with the possible addition of a newer, experimental therapy.
Following initial treatment for mesothelioma, patients enter a period of cancer recovery and survivorship. Cancer survivors may choose to participate in a survivorship care plan, which includes a summary of treatment and a detailed plan that includes follow-up appointments and surveillance for recurrent disease and treatment side effects. The overarching goal of a survivorship care plan is to ensure that patients with mesothelioma continue to receive care and support during recovery.