Prevention of malignant seeding at drain sites after invasive procedures (surgery and/or thoracoscopy) by hypofractionated radiotherapy in patients with pleural mesothelioma.

Introduction: Literature data show that mesothelioma cells can implant along the surgical pathway of invasive procedures such as thoracotomy and thoracoscopy. We investigated the use of hypofractionated radiotherapy for preventing such malignant seeding.

Material And Methods: Thirty-two consecutive patients diagnosed with pleural mesothelioma were included in the present retrospective study. All patients underwent surgery and/or thoracoscopy for diagnosis, staging or talc pleurodesis. They were treated with electron external beam radiation therapy (21 Gy in 3 fractions over 1 week), directed to the surgical pathway after the invasive procedure. After completion of radiation treatment, 20 of 32 patients (63%) underwent chemotherapy.

Results: After a mean follow-up of 13.6 months (range 3-41) from the end of radiation therapy, no patient had tumour progression in the treated area. The treatment was well tolerated, as only erythema grade I (Radiation Therapy Oncology Group, RTOG, scale) was noted in 11 patients. Seventeen patients died of disease with local progression after a mean survival time of 12.6 months (range 3-27); thirteen patients are alive with disease after a mean follow-up of 13.9 months (range 4-41); two patients are alive without evidence of disease after a mean follow-up of 16.50 months (range 6-27).

Discussion: The present study shows the efficacy and safety of local radiotherapy in preventing malignant seeding after thoracoscopy in patients with pleural mesothelioma although larger prospective trials are probably still needed to validate this treatment approach.