A New Approach to Reducing Mesothelioma Risk in Asbestos-Exposed People

The Japanese researchers who first suggested that removing iron from the body could help prevent malignant mesothelioma have come up with a way to make the process even easier and safer.

In their original 2016 study, scientists at Nagoya University Graduate School of Medicine induced a pre-mesothelioma state in lab rats by injecting their abdomens with deadly crocidolite asbestos.

As predicted, the rats exhibited all the precursors to the development of peritoneal mesothelioma – inflammation, higher iron levels, and oxidative stress. The team then attempted to lower the risk and stave off mesothelioma by giving the rats an iron-removing agent called desferal.

Excess Iron Can Lead to a Mesothelioma Diagnosis

The good news from the original study is that removing iron did appear to have a mesothelioma-fighting effect on the rats.

The rats had significantly less scarring and thickening of their peritoneum, the lining of the abdomen where peritoneal mesothelioma tumors grow, much less cancer-feeding iron in their tissues, and lower levels of oxidative stress.

Inflammation, iron overload, and oxidative stress have all been shown to play a role in the development of malignant mesothelioma.

The problem is that desferal can have adverse side effects, including dizziness, itching, numbness or pain, and gastrointestinal upset. The newest study gets around these problems by removing iron with phlebotomy (blood removal) instead.

Removing Iron with Phlebotomy

Therapeutic phlebotomy is much like blood donation. It is often used to treat people with hemochromatosis, or too much iron in the blood. In people, each treatment removes about 500 cc of blood and reduces the amount of iron in the body by about 250 milligrams.

In the Japanese experiment, the asbestos-exposed rats received weekly or biweekly phlebotomy treatments from 10 to 60 weeks of age. The rats were then monitored for signs of mesothelioma until they were 120 week old.

Iron Removal Decreased Signs of Mesothelioma

Unfortunately, the rats in the study still developed mesothelioma. But the weight and nuclear grade of the malignant mesothelioma in the treated rats was significantly lower than in untreated rats.

The treatment also reduced the amounts of fluid build-up in the abdomen (ascites), a major cause of mesothelioma symptoms in people. Iron removal with phlebotomy also appeared to reduce the number of cases of sarcomatoid mesothelioma, the deadliest mesothelioma subtype.

Best of all, the regular phlebotomy treatments prolonged the rats’ long-term mesothelioma survival without the complications associated with iron-chelating drugs.

Writing in the journal Cancer Science, lead author Yuuki Ohara concludes, “Our results indicate that appropriate phlebotomy may be a practical preventive measure to attenuate the initiation and promotion capacity of asbestos towards malignant mesothelioma by reducing iron in individuals exposed to asbestos.”

Peritoneal mesothelioma accounts for about 500 of the roughly 2,500 cases of malignant mesothelioma diagnosed in the US each year. Most cases are the result of on-the-job exposure to asbestos.

Sources:

Ohara, Y, et al, “Phlebotomy as a preventive measure for crocidolite-induced mesothelioma in male rats”, November 29, 2017, Cancer Science, Epub ahead of print

Li, J, et al, “Dual preventive benefits of iron elimination by desferal in asbestos-induced mesothelial carcinogenesis”, July 2016, Cancer Science, Epub ahead of print