A new study out of Italy suggests that a person is more likely to be diagnosed with mesothelioma if a sibling has the disease. That is especially true if both siblings were also exposed to asbestos.
Scientists from Sapienza University and the Lazio Regional Health Service in Rome, as well as industrial disease experts from Viterbo, Italy searched a database including 10 percent of the Italian population to find familial clusters of mesothelioma cases. Among the 997 cases of mesothelioma recorded between 1980 and 2012, the team found 34 familial cases and 13 clusters. Together, these clusters accounted for 3.4% of all mesotheliomas in the database.
“The most common clusters were those with affected siblings and unaffected parents,” reports Associate Professor Valeria Ascoli with the Department of Radiological, Oncological and Anatomo-Pathological Sciences at Sapienza University. Seven of these clusters were among people who shared the same occupational exposure to asbestos, the primary cause of mesothelioma.
Three of the clustered Italian mesothelioma cases were among people who encountered asbestos either in the same household or in their surrounding environment. In three of the clusters, there was not enough information about the asbestos exposure history of the mesothelioma patients to say where, or even if, they might have been commonly exposed.
Although there was no evidence of a genetic component in most of the mesothelioma cases reviewed, the 3.4% of cases that occurred in families or communities was enough to convince the researchers that genetic mesothelioma susceptibility could exist. They hypothesize that, in certain people, a genetic propensity toward mesothelioma acts together with asbestos exposure to trigger the disease. However they say the data is not sufficient to estimate what proportion of mesothelioma patients in the study were genetically inclined to develop it.
Mesothelioma is a virulent lung-related cancer directly linked to asbestos inhalation or ingestion. Most mesothelioma patients encountered asbestos in the work place, where they were not properly warned or protected against it. Although several studies like this one have suggested that genetics may play a role, scientists are still at a loss to explain exactly why only a small percentage of asbestos-exposed people develop mesothelioma.
Ascoli, V et al, “Familial malignant mesothelioma: A population-based study in Central Italy (1980-2012)”, March 27, 2014, Cancer Epidemiology, Epub ahead of print