Mesothelioma Diagnosis and Staging

Mesothelioma is one of the most difficult cancers to treat, but improved diagnostic methods and the right combination of treatments can help extend patients’ lives, according to a report published online August 29 in Current Treatment Options in Oncology.

Diagnosing mesothelioma has historically been challenging, because the symptoms can mimic those of other conditions, particularly adenocarcinoma of the lung. Today, immunohistochemical staining and other newer tests are helping doctors more accurately diagnose patients they suspect of having mesothelioma.

According to the report, the optimal diagnostic procedure is thoracoscopy, which uses a long, thin tube with a camera attached to view the lungs and take a sample of tissue (biopsy). Computerized tomography (CT) and positron emission tomography (PET) scans can also be helpful.

“PET scans will light up the hottest spot, and that’s the area you want to biopsy,” says lead study author Raja Flores, MD, associate professor of cardiothoracic surgery at Cornell University Medical College, and attending surgeon at the Memorial Sloan-Kettering Cancer Center. CT scans can reveal small tumors in the lining of the lungs (pleura). However, because they often underestimate the amount of disease in the lungs, these scans are less than ideal for predicting which patients might benefit from surgery. Researchers are currently investigating whether markers in the blood such as osteopontin and mesothelin might be more accurate methods for identifying mesothelioma.

Once any cancer diagnosis has been made, doctors stage the cancer to determine the extent of the tumor and how far it has spread. However, when it comes to staging mesothelioma, the system is far from perfect. “The problem with mesothelioma [staging] is they lump everybody together—stage I with stage II with stage III with stage IV,” Dr. Flores says. “When you treat any other kind of lung cancer, you would treat stage I very differently from the other stages. For mesothelioma they’re doing the opposite.” Staging the cancer correctly is critical, because it helps doctors plan out treatment.

Dr. Flores and other experts are currently reevaluating the mesothelioma staging system, but until the system has been revised, it’s important for physicians to send their mesothelioma patients to a trio of doctors—a thoracic surgeon, medical oncologist, and radiation oncologist—to plan out the most appropriate therapy. “It’s important for physicians to send patients to a surgeon first so they can determine the stage and what mode of treatment is best,” he says.

For patients with early-stage disease, that optimal treatment is surgery to remove the lung (extrapleural pneumonectomy) or to remove the diseased lung lining (pleurectomy with decortication). “I will never say someone can be cured of mesothelioma,” Dr. Flores says. “However, surgery will help them live much longer with a better quality of life.” He says surgery can extend a patient’s lifespan by two years or more, depending on the stage of the cancer. In the context of a disease that has an average survival of one year, that’s a significant increase in lifespan.

Surgery is effective, but it shouldn’t work alone, according to Dr. Flores. Radiation and chemotherapy also play important roles in mesothelioma therapy. One chemotherapy regimen in particular has been generating interest in the medical community—combinations of the platinum-based chemotherapy drug cisplatin with either gemcitabine or pemetrexed.

Doctors are awaiting the results of future trials to enhance their understanding of these treatments. For now, Dr. Flores says surgery plus radiation and/or chemotherapy offers mesothelioma patients the best hope for survival.

Source:

Kent M, Rice D, Flores R. Diagnosis, Staging, and Surgical Treatment of Malignant Pleural Mesothelioma. Curr Treat Options Oncol. 2008. Epub ahead of print.