Prophylactic irradiation of intervention sites in malignant pleural mesothelioma.

BACKGROUND AND PURPOSE: To assess the effectiveness of prophylactic irradiation of intervention track (PIT) to prevent tumor seeding in patients with malignant pleural mesothelioma. MATERIALS AND METHODS: A retrospective review was conducted of 171 patients with a histological diagnosis of pleural mesothelioma with some undergoing prophylactic irradiation of intervention sites. RESULTS: Forty-eight patients (28%) received PIT. A majority of patients were followed until death. Thoracoscopy (88%) was the procedure most often performed. Thirty-three percent of patients received chemotherapy. The median dose of PIT was 21 Gy in 3 fractions with electrons or 6 MV photons. The local progression free survival (LPFS) at the intervention site was significantly higher in the PIT group and was not influenced by chemotherapy. At 6 months, LPFS for the intervention sites was 91% with PIT and 74% without PIT (p=0.002). During the follow-up, 6 patients (13%) in the PIT group had tumor invasion of the subcutaneous tissue compared to 40 patients (33%) in the group without PIT (p=0.008). CONCLUSIONS: This study suggests that PIT in mesothelioma reduces the incidence of procedure tract metastasis. Finally, chemotherapy does not seem to have an influence on the incidence of tract metastasis.