Mesothelioma is a rare cancer affecting the thin linings of the chest and abdomen, with its primary cause being exposure to asbestos. The disease develops silently over decades, making it difficult to detect in its initial stages. Symptoms are often mistaken for more common conditions, which leads to a diagnosis only after the cancer has advanced. This challenge highlights the need to understand who is at risk and what signs to look for.
Identifying High-Risk Populations
The most significant risk factor for mesothelioma is occupational exposure to asbestos. Industries like construction, shipbuilding, mining, and manufacturing historically used asbestos-containing materials, putting workers at high risk. Military veterans, particularly those who served in the Navy, were also frequently exposed on ships and in naval yards where asbestos was used for insulation and fireproofing.
This risk is not limited to those who directly handled asbestos. Family members of exposed workers could develop the disease through secondary exposure from fibers carried home on a worker’s clothing, skin, and hair. People living near asbestos mines or processing facilities also face an increased risk from environmental exposure.
A defining characteristic of mesothelioma is its long latency period, the time between asbestos exposure and the appearance of symptoms. This period can range from 20 to 60 years, meaning individuals exposed decades ago may only now be developing the disease. This long delay makes it difficult to connect symptoms to a past exposure.
Recognizing Early Symptoms
The initial signs of mesothelioma are subtle, and the specific symptoms depend on where the cancer is growing. For pleural mesothelioma, which affects the lining of the lungs and is the most common form, early indicators include a persistent dry cough, shortness of breath, and pain in the chest or lower back. Some individuals may also experience unexplained weight loss, fatigue, or difficulty swallowing.
When the cancer develops in the lining of the abdomen, it is known as peritoneal mesothelioma. Its symptoms relate more to the digestive system and can include abdominal pain or swelling, changes in bowel habits, and a feeling of fullness. Unexplained weight loss is also a common symptom.
Because these symptoms are non-specific, they are often attributed to conditions like pneumonia or irritable bowel syndrome. This vagueness is a primary reason why mesothelioma is frequently diagnosed at a later, more advanced stage.
Screening and Emerging Tests
For individuals with a known history of asbestos exposure, screening can help detect mesothelioma before symptoms emerge. While no universal screening guidelines exist, some doctors recommend regular imaging for high-risk individuals. Low-dose computed tomography (LDCT) scans may be used to look for early changes in the lungs or abdomen, such as fluid buildup or thickening of the lining.
In addition to imaging, researchers have identified biomarkers that can be measured through blood tests. One test, MESOMARK, measures soluble mesothelin-related peptides (SMRPs) in the blood. Elevated SMRP levels can be an indicator of mesothelioma, but these blood tests are not definitive, as other conditions can also raise biomarker levels.
Other biomarkers are also under investigation. Proteins like fibulin-3 and High Mobility Group Box 1 (HMGB1) have shown potential in identifying early-stage disease. These emerging tests, used with imaging, provide a more comprehensive approach to screening for high-risk individuals who may require further evaluation.
The Diagnostic Confirmation Process
When screening or persistent symptoms suggest mesothelioma, the diagnostic process begins with advanced imaging. CT scans, positron emission tomography (PET) scans, and magnetic resonance imaging (MRIs) are used to determine the location, size, and extent of the disease. A PET scan is particularly useful for detecting areas of high metabolic activity, which can indicate the presence of cancer.
While imaging provides strong evidence, a biopsy is the only way to definitively confirm a mesothelioma diagnosis. This procedure involves taking a small tissue sample from the affected area for examination. Depending on the tumor’s location, a surgeon may perform a thoracoscopy (for the chest) or a laparoscopy (for the abdomen) to retrieve a sample. A less invasive needle biopsy may also be used.
The biopsy confirms the presence of cancerous cells and identifies the specific cell type. Mesothelioma tumors are composed of epithelioid cells, sarcomatoid cells, or a mix of both (biphasic). Knowing the cell type is important for determining the patient’s prognosis and guiding the course of treatment.