Mesothelioma patients who have thoracoscopic surgery should not necessarily have radiation to keep their cancer from spreading at the surgical site. That’s the conclusion of researchers in Oxford, England who recently published an article on the practice of prophylactic irradiation therapy (PIT) for mesothelioma.
Malignant pleural mesothelioma, a serious asbestos-linked lung cancer, is notoriously difficult to diagnose and treat. Because blood and imaging tests are often inconclusive, for a definitive diagnosis many patients have to undergo surgery to remove mesothelioma tumor cells for examination under a microscope. With the use of a thoracoscope, a camera for viewing inside the chest cavity, this procedure can often be done through small puncture wounds instead of the large open incision it used to require. Video-assisted thoracoscopic surgery (VATS) results in less pain and a faster recovery for most mesothelioma patients.
But there are risks to thoracoscopic surgery. In some cases, mesothelioma patients who undergo VATS develop metastases, or cancer ‘seeds’, at the site of the surgical intervention. Because of the risk of spreading the mesothelioma they are trying to diagnose, some centers treat the intervention site with radiation as a preventive measure.
After analyzing more than 300 papers on the practice, and carefully scrutinizing the 9 most relevant studies, the researchers at Oxford University have come to the conclusion that PIT is not justified and may even be harmful. Writing in the Journal of Interactive and Cardiovascular Thoracic Surgery they explain, “One trial found that 23% of radiotherapy patients developed tract metastases compared to 10% of control patients… Time from procedure to tract metastases was in fact shorter in patients treated with RT (2.4 month RT vs. 6.4 months control). Another trial found that seeding of metastatic tumor to the intervention site occurred in 7% of RT sites vs. 10% of control sites.” There was no significant survival difference between the two groups.
Although at least one of the studies cited did show a higher number of metastases in the control group vs. the PIT group, several non-randomized studies found mixed results. Additionally, other studies have found no evidence that mesothelioma patients who develop tract metastases die sooner or have more pain than those who don’t. Since radiation therapy can cause fatigue and other side effects, the authors of another paper on the topic recommend the doctors carefully watch the pleural puncture sites for metastases and use radiotherapy only if they start to cause symptoms.
Nagendram, M et al, “Should all patients who have mesothelioma diagnosed by video-assisted thoracoscopic surgery have their intervention sites irradiated?”, March 30, 2011, Journal of Interactive Cardiovascular and Thoracic Surgery, Epub ahead of print. Davies, Helen et al, “Prophylactic radiotherapy of pleural puncture sites in mesothelioma: The controversy continues”, December 08, 2008, Current Opinion in Pulmonary Medicine, pp. 326-330.