Possible Blood Test for Early Stage Pleural Mesothelioma

Review
NEW YORK, Oct. 12 - Discovery of a biomarker that reveals pleural mesothelioma at an early stage may lead to a blood test that can detect this asbestos-related lung malignancy for meaningful therapy.

Patients with pleural mesothelioma had significantly higher serum levels of the protein osteopontin, compared with those who had been exposed to asbestos but did not have the disease, according to a study led by Harvey Pass, M.D., of New York University.

The goal is to detect pleural mesothelioma early, because patients with stage IA disease can survive five or more years with prompt surgery to remove the tumor, Dr. Pass and colleagues said in a study reported the Oct. 13 issue of the New England Journal of Medicine.

Yet the difficulty in detecting this disease means it is diagnosed this early only about 5% of the time, and with advanced disease surgery prolongs life by only about three months, added Dr. Pass, a thoracic surgeon, and colleagues.

The study compared 69 patients with asbestos-related but non-malignant pulmonary disease, 45 disease-free participants without asbestos exposure, and 76 patients with pleural mesothelioma. The researchers compared serum osteopontin levels among these groups.

Mean serum osteopontin levels were significantly lower in those without asbestos exposure than in those with asbestos exposure and non-malignant pulmonary disease (14±6 ng/ml vs. 56±13 ng/ml; P=0.03).

The mean serum osteopontin level in the group with pleural mesothelioma was significantly higher than in the group exposed to asbestos with non-malignant disease (133±10 ng/ml; 95% confidence interval=113-154 vs. 30±3 ng/ml; 95% CI= 23-36; P<0.001).>

Using a cutoff value of 62.4 ng/ml of osteopontin, a blood test to detect stage IA pleural mesothelioma in those with asbestos exposure and non-malignant lung disease had a sensitivity of 84.6% and a specificity of 88.4%.

"This finding, if confirmed, would have immediate clinical applications, because the use of therapy could potentially influence survival among patients with stage I pleural mesothelioma," the investigators said.

"Overall, results are better than or rival those of any other available test, of which several have now been described," said Mark. R. Cullen, M.D., of Yale in an accompanying editorial.

"The practical value of this approach as a diagnostic test overall, however, must await the assessment of serum osteopontin levels in other disorders common after extensive exposure to asbestos… from which mesothelioma must commonly be differentiated," Dr. Cullen said.

Once considered rare, the incidence of pleural mesothelioma is increasing worldwide, probably because of asbestos exposure many years ago, and the long latency period between asbestos exposure and the onset of disease, according to a review article in the same issue of NEJM by Bruce W.S. Robinson, M.D., and Richard A. Lake, Ph.D., of the University of Western Australia in Perth.

The incidence of pleural mesothelioma is 15 per million per year in the United States, 18 per million in Europe, and 40 per million in Australia, Drs. Robinson and Lake said.