The International Association for the Study of Lung Cancer (IASLC) says the current strategy for staging malignant pleural mesothelioma may need to be modified.
According to an international team of IASLC member researchers, the current system, which was established by the International Mesothelioma Interest Group (IMIG) and has been widely used, has a number of flaws. First, in part because it was based on a retrospective analysis of a small group of mesothelioma surgical patients, it has limited value in clinical staging. In addition, the IMIG mesothelioma staging guidelines use descriptors for lymph node involvement which the IASLC researchers say may not be relevant to mesothelioma.
Because of these shortcomings, the IASLC has announced that it will work with the IMIG to establish new staging criteria for mesothelioma. To make the new criteria as accurate and relevant as possible for clinicians, the process will start with the development of a large international database of patients. In a study published in the Journal of Thoracic Oncology the IASLC team has started the process by evaluating 3,101 mesothelioma patients from 15 centers located in four continents.
In cancer staging, the ‘T’ classification refers to the size of the tumor and whether it has invaded nearby tissue. To improve the T-classification factor in mesothelioma, the IASLC researchers suggest that measurement based on tumor volume (rather than just dimensions) could “enhance the current T descriptors.”
Evaluation of the mesothelioma patients also found a difference in survival among patients with lymph node involvement and those whose lymph nodes had not been affected. But the difference between patients with involvement of lymph nodes closest to the cancer (N1) and those with more distant lymph node involvement (N2) is less clear. This prompted the IASLC researchers to conclude that “additional study of the extent of lymph node involvement might yield improvements in the N-classification factor.”
Finally, the authors suggest that even the broad stage I, II, III, and IV categories themselves may need to be reassessed. Currently, most of the mesothelioma patients who were included in the study were surgical patients, which may limit the applicability of the findings to other types of patients. In a press release on their findings the IASLC researchers conclude, “The addition of a larger group of patients with more advanced disease, staged clinically and managed non surgically may help determine whether stages III and IV should be classified into a and b subcategories.”
Founded in 1974, the IASLC is the only global organization dedicated exclusively to the study of lung cancer.