Does Smoking Cause Mesothelioma?

Mesothelioma is a type of cancer that develops in the mesothelium, a protective lining that covers most of the body's organs. Most mesothelioma develops in the pleura (the lining of the lungs and chest cavity) or the peritoneum (the lining of the abdominal cavity). It can also develop in the pericardium (lining of the heart) or in the lining of the reproductive organs.

The most common cause of mesothelioma is asbestos exposure; 70 to 80 percent of mesothelioma cases occur in people with histories of asbestos exposure at their places of work. Asbestos miners, people who work in asbestos plants, construction and heating workers and shipyard hands are among the groups most at risk of developing mesothelioma. There is some increased risk for family members and people who live with someone who works with asbestos.

Smoking damages the pleura in the lungs, thus rendering them incapable of performing their task of receiving oxygen. Because so many cases of mesothelioma occur in the pleura covering the lungs, it is often thought that smoking causes mesothelioma. Smoking by itself does not cause mesothelioma. However, people who are exposed to asbestos are at higher risk for lung cancer, and combining smoking and asbestos exposure greatly increases this risk. In fact, more people who are exposed to asbestos die of lung cancer than of mesothelioma. The American Cancer Society reports that people who smoke after being exposed to asbestos can cut their risk of developing lung cancer by 50 percent within 5 years of quitting the habit.

Mesothelioma symptoms vary depending on where the cancer has occurred. Pleural (lung) mesothelioma can cause shortness of breath, lower back pain and chest pain. Other symptoms include difficulty swallowing, coughing and fatigue. People with pleural mesothelioma may cough up bloody fluid. Peritoneal (abdominal) mesothelioma symptoms are abdominal pain and swelling, nausea, vomiting, reduced bowel function and weight loss.

Unfortunately, mesothelioma comes with a poor prognosis: only 20 percent of patients survive 5 years after diagnosis. Mesothelioma doesn't respond particularly well to conventional treatments such as surgery, chemotherapy and radiation. A combination of all three of these treatments has the best results, but all at once is an extremely aggressive treatment that can cause many side effects.

The National Cancer Institute runs clinical trials of experimental treatments that mesothelioma patients may be eligible for (see Resources). Targeted drugs are also in development. The chemotherapy technique called heated intraoperative intraperitoneal chemotherapy involves applying hot chemotherapy drugs directly to the tumor. Immunotherapy (a treatment that encourages the immune system to attack malignant cells) has shown some promise.