High-dose radiation “arguably” best treatment for pleural mesothelioma, researcher says
New research presented in Europe this week suggests that high-dose radiotherapy, once thought to be of marginal benefit to mesothelioma patients, may be the most effective treatment when the disease is confined to one side of the chest.
From 2003 to 2011, researchers in Melbourne, Australia, gave six weeks of intensity-modulated radiation therapy, or IMRT, to 45 patients with advanced-stage pleural mesothelioma. All but two patients had undergone chemotherapy or had surgery prior to the radiation.
To limit the damage to adjacent tissue and organs — a common hazard of radiation therapy — the researchers used three-dimensional conformal radiation, which shapes the beams of radiation to match the tumor. The 3D technique allows higher, more effective levels of radiation to attack and shrink or kill tumors.
The 45 patients had a median overall survival of 12.4 months from the start of treatment. Nearly 40 percent of the patients lived two years, and about 7 percent survived for five years. Fifteen patients are still living, according to the study, which was presented at the 3rd European Lung Cancer Conference in Geneva.
Malcolm Feigen, the lead researcher, said all but one of the 26 deaths was the result of disease in lung areas that did not receive radiotherapy. He said that other than one “debatable death” from pneumonitis, there were no life-threatening side effects or toxicities.
Because mesothelioma spreads quickly, clinicians have long held that it is difficult if not impossible to administer enough radiation to kill the cancer cells without damaging healthy tissues and nearby organs. Historically, radiotherapy has been used to reduce symptoms in patients with advanced mesothelioma or in conjunction with surgery and chemotherapy for patients with stage I-III of the disease.
Feigen said the results appear to dispel the widespread belief that mesothelioma does not respond to radiotherapy or that the side effects are not worth the effort. “Our experience provides clear evidence that radiation is arguably the most effective single agent for mesothelioma and new technologies including intensity-modulated radiotherapy allow high doses to be delivered safely,” he said.
However, Feigen’s assessment was challenged by Paul Baas of the Netherlands Cancer Institute in Amsterdam. Bass noted that the study’s design did not include a control group and added that while there is “some evidence” that combining three-dimensional conformal radiation with IMRT could limit the risks, high-dose radiation is undoubtedly toxic to healthy tissue and organs and can be especially dangerous to patients undergoing certain chemotherapies.
“I think IMRT in mesothelioma is possible but you have to be aware of the risks,” said Bass, who urged researchers to collaborate in order to better understand the benefits and limitations of radiotherapy for mesothelioma patients.
"I think it is time for a joint study, because if everybody goes on doing what he or she thinks is best at his or her hospital, then we will not be able to compare the results," Bass added.