title: Carbon ion radiotherapy for oligo-recurrent lung metastases from colorectal cancer: a feasibility study.
abstract: BACKGROUND
  The purpose of this study was to evaluate the efficacy and feasibility of carbon ion radiotherapy (CIRT) for oligo-recurrent lung tumors from colorectal cancer (CRC).
  
  
  METHODS
  From May 1997 to October 2012, 34 consecutive patients with oligo-recurrent pulmonary metastases from CRC were treated with CIRT. The patients were not surgical candidates for medical reasons or patient refusal. Using a respiratory-gated technique, carbon ion therapy was delivered with curative intent using 4 coplanar beam angles. A median dose of 60 GyE (range, 44-64.8 GyE) was delivered to the planning target volume (PTV), with a median daily dose of 15 GyE (range, 3.6-44 GyE). Treatment outcome was analyzed in terms of local control rate (LCR), survival rate, and treatment-related complications.
  
  
  RESULTS
  In total, 34 patients with 44 oligo-recurrent pulmonary lesions were treated with CIRT. Median follow-up period was 23.7 months. The 2- and 3-year actuarial LCRs of the treated patients were 85.4% ± 6.2% and 85.4% ± 6.2%, respectively. Overall survival was 65.1% ± 9.5% at 2 years, and 50.1% ± 10.5% at 3 years. Although survival rates were relatively worse in the subsets of patients aged<63 years or with early metastasis (< 36 months after resection of primary site), these factors were not significantly correlated with overall survival (P=0.13 and 0.19, respectively). All treatment-related complications were self-limited, without any grade 3-5 toxicity.
  
  
  CONCLUSIONS
  CIRT is one of the most effective nonsurgical treatments for colorectal lung metastases, which are relatively resistant to stereotactic body radiotherapy. CIRT is considered to be the least invasive approach even in patients who have undergone repeated prior thoracic metastasectomies.
authors.affiliation: Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba 263-8555, Japan. wataru.harry1@gmail.com.
authors.forename: Wataru
authors.initials: W
authors.lastname: Takahashi
authors.forename: Mio
authors.initials: M
authors.lastname: Nakajima
authors.forename: Naoyoshi
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Shigeru
authors.initials: S
authors.lastname: Yamada
authors.forename: Hideomi
authors.initials: H
authors.lastname: Yamashita
authors.forename: Keiichi
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsuji
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kamada
mesh_terms: D000328:Adult; D000368:Aged; D002244:Carbon / Q000627:therapeutic use; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality / Q000532:radiotherapy* / Q000556:secondary; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D063193:Heavy Ion Radiotherapy; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality / Q000532:radiotherapy* / Q000556:secondary; D008297:Male; D008875:Middle Aged; D012008:Recurrence; D012189:Retrospective Studies
chemical_list: D002244:Carbon