Asbestos is a mineral formerly used in building construction, and exposure to its fibers has been linked to a rare form of cancer called malignant mesothelioma.

While most cancers are thought to be monoclonal— or caused by mutations in a single cell— researchers at the University of Hawaii Cancer Center have analyzed biopsies and found that malignant mesothelioma is likely caused by mutations in multiple cells.  

Researchers studied the early development of the female embryo and observed that one of the two X chromosomes becomes inactivated, and this inactivation is passed on to all subsequent cells, according to a news release. They then used a process called HUMARA assay to trace this inactivated X and determine whether the cancer was monoclonal.

Study authors performed HUMARA assay on 16 samples from 14 tumor biopsies from women with mesothelioma. Next, they compared those samples to control DNA samples from a healthy male and female, as well as a known monoclonal cell line.

"Our study indicates that malignant mesothelioma is the result of polyclonal tumors, a finding that has implications for our understanding of the disease and the clinic,” lead researcher Michele Carbone from University of Hawaii, said in the news release. “For example, patients that have their tumors removed at the early stages of this type of cancer will most often go on to have a recurrence in spite of the appearance of the eradication of malignant mesothelioma. This new insight helps us understand why that may be."

According to the news release, these findings may aid in the advent of genomic medicine that treats tumors.

"Our findings underscore the need to attack simultaneously several different molecular targets to try to eliminate the different malignant mesothelioma cell clones, as each clone may carry its own distinct set of molecular alterations,” Carbone said.

The study was published in the Journal of Translational Medicine.