While mesothelioma and lung cancer can develop after exposure to asbestos, each occurs in different areas of the body. Lung cancer develops in the lung itself, while mesothelioma usually develops in the lining of the lung. Mesothelioma can also develop in the lining of the abdomen, heart or testicles.

The two cancers grow differently. Lung cancer tends to grow in individual masses with defined boundaries. Mesothelioma starts as tiny tumor nodules that scatter the mesothelial lining, and eventually grow together to form a sheath-like tumor around the organ.

Mesothelioma is almost exclusively the result of asbestos exposure, while the majority of lung cancer cases are attributed to causes like tobacco use and environmental exposures to radon gas and second-hand smoke.

And while smoking does not influence risk of mesothelioma, it greatly increases an individual's risk of developing lung cancer. Those with the highest risk of lung cancer are smokers with a history of asbestos exposure.

By themselves, each risk factor damages lung tissue and makes it more susceptible to diseases. So when smoking and asbestos are combined, an individual's lung cancer risk increases at least fiftyfold.

To diagnose either type of cancer, a doctor may perform an X-ray, a bronchoscopy or a biopsy. During a bronchoscopy, the doctor inserts a tube down the throat and into the airways of the lung to detect abnormalities such as visible tumor growth. If the doctor finds irregular growth, he or she may collect a cell sample and test it for cancer.

In a biopsy, the doctor removes a small portion of suspicious tissue and tests it for cancer growth. The doctor may be able to perform this procedure using only a needle and no incision. To collect a larger sample, however, he or she may need to perform a minor biopsy surgery.

Another test is performed only when doctors suspect a patient has lung cancer. In this test, called sputum cytology, the doctor collects and tests a sample of thick phlegm that the patient coughed up from the lungs. This test may reveal abnormalities like blood or cancerous cells in the phlegm.

For mesothelioma and lung cancer, treatment options largely depend on how much the cancer has spread. Most treatment plans include some combination of surgery, radiation therapy and/or chemotherapy.

If the cancer is localized to the lung area, surgery may be able to remove all or most of the tumor growth. But surgeries vary by specific type of cancer.

Examples:

• To treat pleural mesothelioma a surgeon may remove the lining of the lung, the affected portion of the lung or the entire cancerous lung.
• Typical lung cancer surgeries include removing a small portion of the lung, a lobe of the lung or the entire lung.

For both types of cancer, chemotherapy and radiation therapy are also considered standard courses of treatment. If the mesothelioma or lung cancer is localized, either treatment can be used to shrink tumor growth and potentially kill all tumor cells. When used in this potentially curative way, chemotherapy and radiation therapy are typically combined with surgery. These treatments can still be used if the cancer has spread beyond its original location. In these cases, treatments are palliative and aim to reduce symptoms.

Experimental therapies are being tested through clinical trials for both cancers. Some of these innovative therapies include immunotherapy, gene therapy, photodynamic therapy and cyrotherapy. Photodynamic therapy is used more routinely in the treatment of lung cancer than in mesothelioma.

One year after diagnosis, survival rates for lung cancer and mesothelioma are close: 42 percent for lung cancer patients 39 percent for mesothelioma patients. Survival rates diverge after several years, with lung cancer patients having a long-term survival advantage. A decade after diagnosis, 10 percent of lung cancer patients and 4 percent of mesothelioma patients are alive.

Beyond the statistics, though, is the need for someone with an asbestos cancer to secure an accurate diagnosis: Is it asbestos-related lung cancer or is it mesothelioma? The next step would be to formulate the best individual treatment plan.