Malignant pleural mesothelioma, a virulent form of cancer caused by exposure to asbestos, is difficult to diagnose and to treat. Now, a European medical group is hoping to help oncologists streamline the process with a set of newly released clinical practice guidelines.
The guidelines from the European Society for Medical Oncology (ESMO) state that most mesothelioma patients first present with shortness of breath (in the early stages of the disease) or chest pain (at a more advanced stage). While X-ray can detect the tell-tale thickening of the chest wall surrounding the lungs, a test of the built-up lung fluid and an occupational history are also necessary to make a diagnosis. If examination of the lung fluid is not conclusive, the oncologist may turn to the ‘gold standard’ for mesothelioma diagnosis: examination of a tissue sample obtained through a biopsy.
The guidelines also suggest that two protein markers found in blood serum – mesothelin-related proteins and osteopontin – may also help support a mesothelioma diagnosis, but their role in the disease is still uncertain.
According to the ESMO, staging for mesothelioma should be done using a CT scan. However, if a CT scan does not yield enough information to accurately determine the stage of the disease, a camera-equipped tool such as a thorascope may also help. Two sets of staging guidelines may be used to guide physicians: the IMIG staging system which is based on the extent of post-surgical disease or the European Organization for Research and Treatment of Cancer prognostic scores. The possibility of using PET scanning to detect the spread of mesothelioma beyond the lungs when considering radical surgery may prove helpful but is still being investigated.
Although new and experimental treatments are in development, current accepted therapies for mesothelioma fall into three main categories: surgery, radiotherapy and chemotherapy. The ESMO guidelines say that surgery should be considered in earlier stages of mesothelioma and should only be performed by an experienced thoracic surgeon as part of a multidisciplinary team. While surgery is often followed by radiation, the effectiveness of radiotherapy in mesothelioma is limited by the challenge of treating a large area of diseased mesothelium without damaging critical healthy lung tissue.
The mesothelioma guidelines’ authors say a combination of the chemotherapy drugs pemetrexed or raltitrexed and cisplatin have been shown to improve survival rates and lung function in clinical trials.
Although mesothelioma is rare, its incidence is predicted to double in the next 20 years due to its long latency. The new ESMO guidelines appear in the August issue of the Annals of Oncology.
Stahel, RA et al, “Malignant pleural mesothelioma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up”, Annals of Oncology, August a2010, Volume 21, Issue 5, pp.126-128.