Prophylactic irradiation of intervention sites in malignant pleural mesothelioma.

Abstract

To assess the effectiveness of prophylactic irradiation of intervention track (PIT) to prevent tumor seeding in patients with malignant pleural mesothelioma. A retrospective review was conducted of 171 patients with a histological diagnosis of pleural mesothelioma with some undergoing prophylactic irradiation of intervention sites. 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). 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.