New research suggests that a protein often used to help diagnose and track malignant mesothelioma may also be a valuable prognostic indicator.
Soluble mesothelin-related protein (SMRP) is a biomarker for pleural mesothelioma, an aggressive asbestos-linked cancer that causes few symptoms until in its late stages. The presence of SMRP in the blood indicates that mesothelial cells on the lining around the lungs have been damaged.
By testing the level of SMRP in the blood of a person with suspected mesothelioma, doctors can both confirm the diagnosis and track how well mesothelioma treatments are working. The Mesomark laboratory test for SMRP has become a staple of mesothelioma care in recent years.
Determining Mesothelioma Prognosis
Many factors influence mesothelioma prognosis, or likelihood of survival, including a person’s overall health, the histology or type of mesothelioma a patient has, and how far it has spread. Although SMRP has been used to identify and track the asbestos cancer, its value as a prognostic tool is still uncertain.
In a new meta-analysis on SMRP and prognosis, mesothelioma researchers with Sichuan University examined data from eight other mesothelioma studies including 579 pleural mesothelioma patients. Overall survival times were compared to patients’ SMRP levels.
“The results showed that soluble mesothelin level was significantly correlated with the survival of malignant pleural mesothelioma,” writes Dr. Long Tian, whose name appears first on the paper.
The Chinese analysis confirmed what a number of studies have suggested – that pleural mesothelioma patients with the highest level of SMRP in their blood serum tend to have the worst prognosis.
As with past studies, mesothelioma survival was also significantly correlated with tumor histology and stage; patients with the epithelioid subtype and those in the earliest stages of the disease tended to have the best responses to treatment.
Biomarkers for Mesothelioma
Biomarkers are substances found in unusually high quantities in the blood serum or lung fluid of mesothelioma patients. Because they are either absent in healthy people or only found in very small amounts, testing for biomarkers is one of the best ways to identify certain diseases, including mesothelioma.
Although SMRP is a common biomarker for mesothelioma, it is not the only one. Osteopontin, fibulin-3 and megakaryocyte potentiation factor (MPF) can also be elevated in the blood of mesothelioma patients.
Because these same proteins can also be elevated in people with other types of cancer, additional tests, including imaging tests and/or biopsies, are needed to determine whether a person has malignant mesothelioma.
Tian, L, et al, “Prognostic significance of soluble mesothelin in malignant pleural mesothelioma: a meta-analysis”, April 26, 2017, Oncotarget, Epub ahead of print