Mesothelioma vs. Lung Cancer - What’s the Difference?

Mesothelioma and lung cancer, while both cancerous, have very distinct differences. You may have heard your doctor talk about mesothelioma during the diagnosis process for lung cancer, or about potential risks and chances of developing mesothelioma later in life. Regardless, the more you know about a condition, the better you can be prepared to treat it. Here are some of the major differences between mesothelioma and lung cancer that may help guide any questions for your healthcare team.

Pathology

Mesothelioma and lung cancer develop in very different ways. Lung cancer develops within the lungs themselves, and is often present in distinct masses that have clear borderlines. On the other hand, mesothelioma develops in the pleural lining of the lungs and develops into an interconnected network of tumors that lack clear boundaries. The size of this network and number of tumors is typically large. Staging for both cancers is the same for stages 1-3, where cancerous masses go from being localized to locally advanced to nearby lymph nodes. Staging differs at stage 4, where mesothelioma continues to progress in local tissues, with the occasional spreading to the other lung or bones, while lung cancer progresses and spreads to many other parts of the body.

What causes mesothelioma?

Mesothelioma is typically a result of asbestos exposure. Asbestos is the name for minerals that occur naturally in the environment as bundles of fibers. These fibers can be separated into thin, durable threads and are resistant to heat, fire, and chemicals, and do not conduct electricity. Asbestos has been used in many different products, such as insulation.¹ Asbestos fibers become lodged in the pleural cavity outside of the lungs themselves. Genetics can often play a role in how susceptible our body is to developing mesothelioma after asbestos exposure.

In lung cancer, asbestos can be a risk factor if fibers become lodged in the lung tissue itself but often can come from a variety of different risk factors including smoking, pesticide exposure, pollutants, and radon. Additionally, smoking has no effect on mesothelioma, whereas smoking and smoking cessation can directly affect the risk of developing lung cancer. In both conditions, the time between exposure and development can be as many as 40 years!

Diagnosis and treatment

Diagnostic tests for mesothelioma and lung cancer are similar, with X-rays, as well as PET and CT scans leading the way. The main diagnostic difference lies in the results of tissue biopsies, where mesothelioma resembles adenocarcinomas, and lung cancer presents differently. Additionally, lung cancer can be detected by testing the sputum (phlegm) from an individual. Treatment measures are similar in both cases but vary in success rates. Surgery, radiation, and chemotherapy are often the first lines of treatment in both cases, but due to the lack of distinct boundaries in mesothelioma, their success is often limited for these individuals.

Overall, both conditions can present with the same cancer-related symptoms, such as shortness of breath, fatigue, and weight changes, and these symptoms often don’t present until the condition has progressed significantly. Although they both can come from similar causes, and can present the same, there are definitive differences that you can be tested for to ensure that you have received an accurate diagnosis, and are getting the appropriate interventions.^2-3