Should all patients who have mesothelioma diagnosed by video-assisted thoracoscopic surgery have their intervention sites irradiated?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was whether patients diagnosed with mesothelioma by video-assisted thoracoscopic surgery should have their intervention sites irradiated to prevent metastatic seeding. Altogether 334 papers were found using the reported search, of which nine represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. There is no general consensus in the literature. Four studies recommend prophylactic irradiation therapy (PIT), while three studies stated that PIT was unnecessary. A systematic review identified only three suitable randomized controlled trials (RCTs) from the literature. One trial found that 23% of radiotherapy (RT) patients developed tract metastases compared to 10% of control patients (P=0.748) with an estimated hazard ratio (RT to control) of 1.28 (95% CI: 0.29-5.73). Time from procedure to tract metastases was in fact shorter in patients treated with RT (2.4 months RT vs. 6.4 months control, non-significant). Another trial found that seeding of metastatic tumour to the intervention site occurred in 7% of RT sites vs. 10% of control sites (P=0.53). Freedom from tract metastasis survival was also non-significant between RT and control arms (P=0.82). However, the third trial reported a significantly greater incidence of intervention site metastases in control vs. RT patients (40% vs. 0%, respectively, P<0.001). Non-randomised studies found mixed results. One reported that median survival between patients with and without local metastases was not significantly different (P=0.64) while another article described no local metastases in PIT sites. None of the studies reported significant skin or side reactions and treatment was generally well tolerated. Based on the available evidence, we conclude that PIT is not currently justified.