Peritoneal mesothelioma is much more common among those exposed to asbestos in a non-occupational setting than it is among those who are exposed in the workplace.
According to a recent study done at the Wake Forest University School of Medicine, peritoneal mesothelioma accounted for 9.4 percent of all mesothelioma cases involving occupational exposure, but five times more — 47 percent — of cases stemming from outside the workplace.
Pleural mesothelioma, which involves the thin membrane surrounding the lungs, is the most common form of the cancer and involves an estimated 75 percent of all diagnosed mesothelioma cases.
Peritoneal mesothelioma, the second-most common form of the disease, involves the lining of the abdomen.
The majority of all mesothelioma cases are traced to occupational exposure. It is commonly linked to military service, the construction and shipbuilding industries, and factories and automobile repair shops.
Non-Occupational Asbestos Exposure
The non-occupational exposure typically involves family members of a person who inadvertently brings the asbestos fibers home on his clothes, or from just living in an older dwelling where asbestos is throughout the home.
The Wake Forest study involved 384 mesothelioma patients. Data was obtained from questionnaires and medical records. Graduate student Jennifer Faig conducted the study with assistance from Edward Levine, M.D., and Jill Ohar, M.D..
The subjects came from mesothelioma patients at Wake Forest Baptist Medical Center, from last year's Mesothelioma Applied Research Foundation (MARF) conference and from patients undergoing legal proceedings with various law firms.
The findings were submitted as part of an abstract for the 2012 International Mesothelioma Interest Group Conference scheduled September 11-14 in Boston.
Results further emphasized the lengthy latency period often associated with mesothelioma. The mean latency period from first occupational exposure to diagnosis was 49.1 years for those in the occupational category and 42.7 years for those outside the category.
It also illustrated the growing survival time when the diagnosis is made at a younger age. The median survival of those with occupational exposure, in which almost 91 percent had pleural, was 19.7 months.
The median survival of non-occupational exposure was 56.7 months. Much of the difference, though, was attributed to a later age of diagnosis (67.3 years vs. 51.3 years).
Wake Forest Clinical Trial
Wake Forest is a leader in the study of mesothelioma.
Ohar, who has studied the cancer for more than 20 years, heads up an ongoing a clinical trial that is studying genetic disposition to the disease. As part of her study, she compares the rarity of the cancer to the prevalence of asbestos exposure in America.
"Nearly 27 million individuals in the U.S. were exposed to asbestos in the work place between 1940 and 1979, but just 3,000 new cases of mesothelioma are diagnosed annually," she cites in Genome Wide Association Study in Mesothelioma Compared to Illumina Controls.
She also said that common cancers are three times more likely to occur in mesothelioma patients and their first-degree relatives.
The goal of the trial, which she hopes to complete by December of 2013, is to collect DNA samples from 1,000 mesothelioma patients. They already have collected close to 400.
She is working with centers at the Mayo Clinic, the University of Pennsylvania, the New York University School of Medicine, Johns Hopkins University, Mount Sinai School of Medicine and Memorial Sloan-Kettering Cancer Center, along with MARF.
