SMRP in screening of mesothelioma in asbestos-exposed workers: A study of 1,704 subjects.

Abstract

e12518 Background: The soluble mesothelin-related peptide (SMRP) is a marker in the diagnosis for mesothelioma. The role of SMRP as a potential screening tool in subjects with a past asbestos exposure is being debated. Objective: to evaluate SMRP and incidence of malignant mesothelioma in an asbestos exposed cohort. Methods: 1,704 subjects (Median Age 62) occupationally exposed to asbestos were enrolled in the study. A questionnaire on individual characteristics, disease history, and occupational or non-occupational exposure to asbestos was administered. All subjectsunderwent clinical examination and collection of serum sample for SMRP measurement that were repeated after 1 and 2 years. The samples were stored at -80 °C until assayed. Results: Median baseline SMRP was 0.45 nmol/l (range 0.1-4.45). SMRP was higher than 1.5 nmol/l (defined as cut-off) in 40 participants. 9 subjects had recognized lung cancer at the time of screening (median baseline SMRP 0.65 nmo/l, range 0.1-1.7) and 109 had recognized tumors at other sites (median 0.52 nmol/l, range 0.1-3.0). Overall, median follow-up of all subjects was 31.5 months During follow-up, recurrent or metastatic tumors were observed in 23 out of 118 tumors. Sixty-one subjects developed a new tumor. An epithelioid pleural mesothelioma occurred in two subjects, 13 and 17 months after the last SMRP evaluation, respectively. Baseline SMRP was 0.52 nmol/l and 0.17 nmol/l, respectively. In subjects with tumor, SMRP increased of 20-50% in 13 subjects (15%), two of them with abnormal SMRP (1 bladder and 1 prostate cancer). An increase greater than 50% was found in 19 subjects (22%). SMRP was higher than the threshold value in 3 tumors (1 lung, 1 colon and 1 prostate, diagnosed 2 months from last SMRP measure). Overall, mesothelin was above the cut-off in 58 subjects without any evidence of neoplastic disease. Conclusions: we cannot confirm the predictive role of SMRP for mesothelioma because we found two cases with low mesothelin levels 13 and 17 months before the diagnosis. The low number of mesotheliomas could be due to the low median age of our population. It will be intriguing to follow up in the future the subjects that showed an increase of SMRP.