MSLN and mesothelioma: However, although most patients with mesothelioma have raised serum levels of SMRP, giving a sensitivity of between 80–83% and specificity between 80–100% [43–45], it is mostly associated with the epithelioid sub-type, leading to difficulties in identifying the other sub-types of mesothelioma, especially sarcomatoid, using this marker alone [46].