title: Tomotherapy improves local control and changes failure patterns in locally advanced malignant pleural mesothelioma.
abstract: OBJECTIVE
  The purpose of the study was to determine whether intensity modulated radiation therapy delivered via helical tomotherapy improves local control (LC) after pleurectomy/decortication (P/D) for malignant pleural mesothelioma compared with 3-dimensional conformal radiation therapy (3D-CRT).
  
  
  METHODS
  Forty-five consecutive patients were treated with adjuvant radiation to 45 Gy in 1.8 Gy fractions after P/D between 2006 and 2014; 23 received 3D-CRT, and 22 received tomotherapy. Kaplan-Meier analysis was used to calculate overall survival, time to in-field or local failure (LF), and time to out-of-field failure. The Student t test and Fisher exact test were used to detect between-group differences.
  
  
  RESULTS
  Median follow-up time was 19.4 months and 12.7 months for the 3D-CRT and tomotherapy groups, respectively. Eighty-two percent of patients had T3/T4 disease, and 64% had positive nodes; 17.4% and 41% of patients in the 3D-CRT and tomotherapy groups had nonepithelioid histology, respectively. Mean planning target volume dose, percentage of planning target volume receiving 100% of the prescription dose, and lung doses were significantly greater with tomotherapy (P < .05), but toxicity rates (including radiation pneumonitis rates) were equivalent. LC was significantly improved with tomotherapy on Kaplan-Meier analysis with outcomes censored at 2 years (P < .05); uncensored, this became a trend (P = .06). Median time to LF was 19 months with tomotherapy and 10.9 months in 3D-CRT (the latter interval being less than the median follow-up in the tomotherapy group). On univariate analysis, treatment modality was the only significant predictor of LC (P < .05). Isolated LF was significantly more frequent with 3D-CRT (P < .05). Conversely, isolated out-of-field failure was significantly more frequent with tomotherapy (P < .05). Overall survival and out-of-field control were not significantly different.
  
  
  CONCLUSIONS
  Tomotherapy after P/D for malignant pleural mesothelioma is associated with improved target coverage that translates into improved LC compared with 3D-CRT. This is related to a change in failure patterns, with isolated LF being more common in the 3D-CRT group and isolated out-of-field failures predominating in the tomotherapy group.
authors.affiliation: Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Amar U
authors.initials: AU
authors.lastname: Kishan
authors.affiliation: Division of Thoracic Surgery, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Cameron
authors.affiliation: Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Pin-Chieh
authors.initials: PC
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Sherri
authors.initials: S
authors.lastname: Alexander
authors.affiliation: Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Sharon X
authors.initials: SX
authors.lastname: Qi
authors.affiliation: Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Low
authors.affiliation: Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Kupelian
authors.affiliation: Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Michael L
authors.initials: ML
authors.lastname: Steinberg
authors.affiliation: Division of Thoracic Surgery, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, California.
authors.forename: Jay M
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Selch
authors.affiliation: Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California. Electronic address: percylee@mednet.ucla.edu.
authors.forename: Percy
authors.initials: P
authors.lastname: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D008297:Male; D008654:Mesothelioma / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D000086002:Mesothelioma, Malignant; D008875:Middle Aged; D009367:Neoplasm Staging; D058958:Organs at Risk; D010994:Pleura / Q000601:surgery*; D010997:Pleural Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D011013:Pneumonectomy / Q000009:adverse effects*; D011183:Postoperative Complications / Q000517:prevention & control*; D011379:Prognosis; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D018714:Radiotherapy, Adjuvant; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*