Mesothelioma vs. Lung Cancer: Key Differences Explained

Overview: Key Differences

Mesothelioma and lung cancer are both serious thoracic cancers, but they are fundamentally different diseases. The most important distinction: mesothelioma is almost always caused by asbestos exposure, while lung cancer has multiple causes including smoking, radon, and other carcinogens.

Causes

Mesothelioma is caused almost exclusively by asbestos exposure. Even brief or low-level exposure can lead to mesothelioma decades later. Smoking does not significantly increase mesothelioma risk.

Lung cancer has multiple causes: smoking (responsible for ~85% of cases), radon gas, asbestos (asbestos workers who smoke have a dramatically elevated risk), air pollution, and genetic factors.

Location in the Body

This is a critical distinction for diagnosis:

• Mesothelioma develops in the lining of the lungs (pleura), abdomen, or heart — not inside the lung tissue itself
• Lung cancer develops within the lung tissue (bronchi, bronchioles, or alveoli)

Symptoms

Both conditions share some symptoms, which contributes to misdiagnosis:

• Both: Shortness of breath, chest pain, cough, fatigue, weight loss
• Mesothelioma-specific: Pleural effusion (fluid around lungs), abdominal swelling (peritoneal type)
• Lung cancer-specific: Coughing up blood, hoarseness, bone pain (if metastasized)

Legal Implications

This is one of the most important differences for patients:

Mesothelioma victims have strong legal rights because asbestos manufacturers knew about the dangers and concealed them. Compensation options include lawsuits, asbestos trust funds, and VA benefits. Average settlements range from $1–$2.4 million.

Lung cancer caused by asbestos exposure may also qualify for compensation, but cases are more complex because smoking complicates causation arguments. An experienced asbestos attorney can evaluate your specific situation.

Fundamental Biological Differences

Mesothelioma and lung cancer are fundamentally different diseases that happen to occur in the same anatomical region. Mesothelioma is a cancer of the mesothelium — the thin membrane that lines the lungs, chest cavity, abdomen, and other body cavities. Lung cancer (carcinoma) is a cancer of the lung tissue itself — the cells that make up the airways and air sacs (alveoli) of the lung. This difference in cell of origin has profound implications for how the diseases behave, how they are diagnosed, how they are treated, and what causes them.

Mesothelioma grows along the surface of the pleura, forming a diffuse sheet of tumor that encases the lung rather than forming a discrete mass within the lung. This growth pattern makes mesothelioma particularly difficult to remove surgically and contributes to its poor prognosis. Lung cancer, by contrast, typically forms a discrete mass within the lung that can sometimes be completely removed by surgery if detected early. The diffuse growth pattern of mesothelioma also makes it more difficult to stage accurately using imaging studies alone.

Causes: A Critical Distinction

The causes of mesothelioma and lung cancer are quite different, and this distinction has important legal implications. Mesothelioma is caused almost exclusively by asbestos exposure — approximately 80% of cases are directly attributable to asbestos, and the remaining cases are caused by other fibrous minerals or are of unknown cause. Smoking does not cause mesothelioma, and the combination of smoking and asbestos exposure does not significantly increase mesothelioma risk beyond the risk from asbestos alone.

Lung cancer, by contrast, has multiple causes. Smoking is the leading cause, accounting for approximately 85% of cases. Other causes include radon gas, air pollution, occupational exposures (including asbestos), and genetic factors. Importantly, asbestos exposure does cause lung cancer — workers with heavy asbestos exposure have approximately 5 times the lung cancer risk of unexposed workers — and the combination of smoking and asbestos exposure is synergistic, increasing lung cancer risk by approximately 50 to 90 times compared to unexposed non-smokers.

Symptoms: Similarities and Differences

Mesothelioma and lung cancer share some common symptoms — shortness of breath, chest pain, and cough — which can make initial differentiation difficult. However, there are important differences. Pleural effusion (fluid around the lung) is much more common in mesothelioma than in lung cancer. Mesothelioma is more likely to cause diffuse chest wall pain, while lung cancer is more likely to cause hemoptysis (coughing up blood). Peritoneal mesothelioma presents with abdominal symptoms that are not typical of lung cancer.

Both diseases can cause constitutional symptoms — fatigue, weight loss, and fever — particularly in advanced stages. The nonspecific nature of these symptoms means that both diseases are often diagnosed at an advanced stage. However, lung cancer screening with low-dose CT scanning is now recommended for high-risk individuals (heavy smokers aged 50-80), which may lead to earlier diagnosis in that population. There is no established screening test for mesothelioma.

Diagnosis: Why Pathology Matters

Distinguishing mesothelioma from lung cancer — and from other cancers that can spread to the pleura — requires careful pathological analysis. The microscopic appearance of mesothelioma cells can resemble that of adenocarcinoma (the most common type of lung cancer) and other cancers. Immunohistochemical staining is essential for accurate diagnosis — mesothelioma cells express certain proteins (such as calretinin, WT-1, and mesothelin) that are not typically expressed by lung cancer cells, while lung cancer cells express proteins (such as TTF-1 and Napsin A) that are not typically expressed by mesothelioma cells.

Misdiagnosis between mesothelioma and lung cancer is not uncommon, particularly when cases are evaluated by general pathologists without specialized experience. The consequences of misdiagnosis can be significant — the two diseases require different treatments, and an incorrect diagnosis can lead to inappropriate treatment and missed legal claims. This is why a second pathological opinion from a major cancer center with mesothelioma expertise is strongly recommended for anyone diagnosed with either disease who has a history of asbestos exposure.

Legal Implications of the Distinction

The distinction between mesothelioma and lung cancer has important legal implications. Mesothelioma is almost always caused by asbestos exposure, making it straightforward to establish causation in a legal claim. Lung cancer caused by asbestos exposure is also compensable, but establishing causation is more complex because lung cancer has multiple causes, including smoking. Defendants in lung cancer cases often argue that smoking, rather than asbestos exposure, caused the cancer — a defense that is not available in mesothelioma cases.

Both mesothelioma and asbestos-related lung cancer are compensable through lawsuits against asbestos manufacturers and trust fund claims against bankrupt manufacturers. However, the compensation available for mesothelioma is generally higher than for lung cancer, reflecting the near-exclusive causal link between mesothelioma and asbestos exposure. If you have been diagnosed with either disease and have a history of asbestos exposure, consulting with an experienced mesothelioma attorney is essential to understand your legal options.

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