title: Effect of increasing experience on dosimetric and clinical outcomes in the management of malignant pleural mesothelioma with intensity-modulated radiation therapy.
abstract: OBJECTIVE
  To assess the impact of increasing experience with intensity-modulated radiation therapy (IMRT) after extrapleural pneumonectomy (EPP) for malignant pleural mesothelioma (MPM).
  
  
  METHODS
  The records of all patients who received IMRT following EPP at Duke University Medical Center between 2005 and 2010 were reviewed. Target volumes included the preoperative extent of the pleural space, chest wall incisions, involved nodal stations, and a boost to close/positive surgical margins if applicable. Patients were typically treated with 9-11 beams with gantry angles, collimator rotations, and beam apertures manually fixed to avoid the contalateral lung and to optimize target coverage. Toxicity was graded retrospectively using National Cancer Institute common toxicity criteria version 4.0. Target coverage and contralateral lung irradiation were evaluated over time by using linear regression. Local control, disease-free survival, and overall survival rates were estimated using the Kaplan-Meier method.
  
  
  RESULTS
  Thirty patients received IMRT following EPP; 21 patients also received systemic chemotherapy. Median follow-up was 15 months. The median dose prescribed to the entire ipsilateral hemithorax was 45 Gy (range, 40-50.4 Gy) with a boost of 8-25 Gy in 9 patients. Median survival was 23.2 months. Two-year local control, disease-free survival, and overall survival rates were 47%, 34%, and 50%, respectively. Increasing experience planning MPM cases was associated with improved coverage of planning target volumes (P=.04). Similarly, mean lung dose (P<.01) and lung V5 (volume receiving 5 Gy or more; P<.01) values decreased with increasing experience. Lung toxicity developed after IMRT in 4 (13%) patients at a median of 2.2 months after RT (three grade 3-4 and one grade 5). Lung toxicity developed in 4 of the initial 15 patients vs none of the last 15 patients treated.
  
  
  CONCLUSIONS
  With increasing experience, target volume coverage improved and dose to the contralateral lung decreased. Rates of pulmonary toxicity were relatively low. However, both local and distant control rates remained suboptimal.
authors.affiliation: Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina, USA. patel073@mc.duke.edu
authors.forename: Pretesh R
authors.initials: PR
authors.lastname: Patel
authors.forename: Sua
authors.initials: S
authors.lastname: Yoo
authors.forename: Gloria
authors.initials: G
authors.lastname: Broadwater
authors.forename: Lawrence B
authors.initials: LB
authors.lastname: Marks
authors.forename: Edward F
authors.initials: EF
authors.lastname: Miles
authors.forename: Thomas A
authors.initials: TA
authors.lastname: D'Amico
authors.forename: David
authors.initials: D
authors.lastname: Harpole
authors.forename: Chris R
authors.initials: CR
authors.lastname: Kelsey
mesh_terms: D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002173:Cancer Care Facilities; D002983:Clinical Competence; D005260:Female; D006801:Humans; D008168:Lung / Q000528:radiation effects; D008297:Male; D008654:Mesothelioma / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D008875:Middle Aged; D009657:North Carolina; D010997:Pleural Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000532:radiotherapy* / Q000601:surgery; D011013:Pneumonectomy / Q000379:methods; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods / Q000592:standards; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods* / Q000592:standards; D012044:Regression Analysis; D012189:Retrospective Studies; D016019:Survival Analysis; D015996:Survival Rate