title: Dosimetric rationale and early experience at UFPTI of thoracic proton therapy and chemotherapy in limited-stage small cell lung cancer.
abstract: BACKGROUND
  Concurrent chemoradiotherapy (CRT) is the standard of care in patients with limited-stage small cell lung cancer (SCLC). Treatment with conventional x-ray therapy (XRT) is associated with high toxicity rates, particularly acute grade 3+ esophagitis and pneumonitis. We present outcomes for the first known series of limited-stage SCLC patients treated with proton therapy and a dosimetric comparison of lung and esophageal doses with intensity-modulated radiation therapy (IMRT).
  
  
  METHODS
  Six patients were treated: five concurrently and one sequentially. Five patients received 60-66 CGE in 30-34 fractions once daily and one patient received 45 CGE in 30 fractions twice daily. All six patients received prophylactic cranial irradiation. Common Terminology Criteria for Adverse Events, v3.0, was used to grade toxicity. IMRT plans were also generated and compared with proton plans.
  
  
  RESULTS
  The median follow-up was 12.0 months. The one-year overall and progression-free survival rates were 83% and 66%, respectively. There were no cases of acute grade 3+ esophagitis or acute grade 2+ pneumonitis, and no other acute grade 3+ non-hematological toxicities were seen. One patient with a history of pulmonary fibrosis and atrial fibrillation developed worsening symptoms four months after treatment requiring oxygen. Three patients died: two of progressive disease and one after a fall; the latter patient was disease-free at 36 months after treatment. Another patient recurred and is alive, while two patients remain disease-free at 12 months of follow-up. Proton therapy proved superior to IMRT across all esophageal and lung dose volume points.
  
  
  CONCLUSIONS
  In this small series of SCLC patients treated with proton therapy with radical intent, treatment was well tolerated with no cases of acute grade 3+ esophagitis or acute grade 2+ pneumonitis. Dosimetric comparison showed better sparing of lung and esophagus with proton therapy. Proton therapy merits further investigation as a method of reducing the toxicity of CRT.
authors: University of Florida Proton Therapy Institute, Jacksonville, Florida 32206, USA.
authors: Rovel J
authors: RJ
authors: Colaco
authors: Soon
authors: S
authors: Huh
authors: Romaine C
authors: RC
authors: Nichols
authors: Christopher G
authors: CG
authors: Morris
authors: Harry
authors: H
authors: D'Agostino
authors: Stella
authors: S
authors: Flampouri
authors: Zuofeng
authors: Z
authors: Li
authors: Dat C
authors: DC
authors: Pham
authors: Abubakr A
authors: AA
authors: Bajwa
authors: Bradford S
authors: BS
authors: Hoppe
mesh_terms: D000368:Aged; D059248:Chemoradiotherapy / Q000009:adverse effects / Q000379:methods*; D005431:Florida; D005500:Follow-Up Studies; D006785:Hospitals, University; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000628:therapy*; D008875:Middle Aged; D009367:Neoplasm Staging; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D011832:Radiation Injuries / Q000453:epidemiology / Q000209:etiology; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D055752:Small Cell Lung Carcinoma / Q000453:epidemiology / Q000473:pathology / Q000628:therapy*; D013997:Time Factors