Radiation

For many decades, it was assumed that the only cause of mesothelioma was exposure to asbestos. However, while asbestos is indeed responsible for most cases of mesothelioma cancer, it has gradually become apparent that there may be some other risk factors for the disease.
Throughout the world, a number of cases of mesothelioma with no apparent connection to asbestos have been diagnosed. As a matter of fact, a 1980 study (McDonald and McDonald) of patients in the U.S. and Canada determined that somewhere between 25 percent and 33 percent of all cases were not related to asbestos exposure. Doctors found this perplexing at first, but with some in-depth research and several official studies, scientists and medical professionals were able to determine that some of these pleural mesothelioma patients had other factors in common. Exposure to radiation was one of those factors.

Radiation Treatments, X-rays, and Mesothelioma

Several dozen cases of mesothelioma following radiation therapy for Hodgkin’s disease have been discovered. A 2005 study entitled “Clinical Course of Thoracic Cancers in Hodgkin’s Disease Survivors” (P. Das, A.K. Ng, M.A. Stevenson, and P.M. Mauch) definitively determined that Hodgkin’s disease patients who were treated with radiation therapy have a high incidence of mesothelioma disease.
Specifically, the study followed 33 patients who were treated at Harvard-affiliated hospitals for Hodgkin’s and subsequently developed mesothelioma, non-small cell lung cancer, or small cell lung cancer. Of those patients that participated, 88 percent had a history of radiotherapy to the thorax as treatment for their disease. Some patients developed thoracic cancer within just a year of being treated for Hodgkin’s. Others developed it more than two decades later. As is usual with mesothelioma, by the time most of these patients were diagnosed, their disease had reached stage III or IV and the prognosis was grim. The median survival rate was only 9 months.
In some cases, peritoneal mesothelioma has also been linked to radiation therapy for breast cancer or any other cancers that may have included radiation delivered to the chest area.
Other research makes a connection between mesothelioma cancer and thorium dioxide, a radioactive substance that was used along with conventional x-rays to diagnose certain conditions. Thorium dioxide was used abundantly from the 1920s until the 1950s.

Atomic Radiation and Mesothelioma

In 1995, the first case of mesothelioma believed to be associated with the dropping of the atomic bomb in Nagasaki was diagnosed. A report on this case, penned by Masami Mizuki, Keiko Yukishige, Yasuharu Abe, and Tomiyasu Tsuda, and published in the journal Respirology in September 1997, suggested that combined exposure to atomic radiation and asbestos (the patient worked for 2 years as a shipbuilder at a munitions factory) is associated with an increased incidence of mesothelioma.
The doctors who authored the study suggested that “If thickening of the pleura or pleural effusion is found in atomic bomb survivors, malignant mesothelioma should be considered as one of the options in the differential diagnosis, even although the atomic bomb attacks occurred several decades ago.”

Atomic Energy Workers and Mesothelioma

Wherever radiation is present, there seems to be a potential connection to mesothelioma. Throughout the last few decades, several individuals currently or formerly employed at atomic energy plants have been diagnosed with this rare cancer, in these instances thought to be caused by constant exposure to low level radiation. (Ionizing radiation: A risk factor for cancer; JE Goodman et al, 2009) The authors concluded that, considering the low rate of mesothelioma in the general population, the increased risk of the disease among radiation-exposed individuals, including those who work at atomic power plants, is significant and should be duly noted.

Making the Connection

Knowing about the link between radiation and mesothelioma is just one more step to making quicker diagnoses and saving more individuals who have been identified as potential victims of the disease. Anyone who has been exposed to radiation of any sort, whether on a regular basis while at work or through x-rays or via therapy for other types of chest cancers, should always inform their doctor as to their medical and occupational history, even if exposure occurred years before. Hence, when symptoms arise - including chest pain, shortness of breath, and coughing – a possible connection can be determined, the correct diagnosis made, and mesothelioma treatment started as soon as possible.