title: Impact of tumor attachment to the pleura measured by a pretreatment CT image on outcome of stage I NSCLC treated with stereotactic body radiotherapy.
abstract: BACKGROUND
  Pleural invasion status is known to be a predictor of survival after pulmonary resection for non-small cell lung cancer. Our goal was to determine whether the length of tumor attachment to the pleura on a pretreatment CT image has prognostic value as an alternative to pleural invasion status for stage I non-small cell lung cancer treated with stereotactic body radiotherapy (SBRT).
  
  
  METHODS
  A total of 90 tumors in 87 patients (males: 68, females: 19) who received SBRT between March 2005 and September 2011 in our institution were reviewed. The median age of the patients was 78 years (range, 48-90 years). The median tumor diameter was 2.2 cm (range, 0.9-4.2 cm). The prescribed dose was typically 48 Gy in 4 fractions, 60 Gy in 8 fractions or 60 Gy in 15 fractions to the isocenter with 6 MV X-ray using 4 non-coplanar and 3 coplanar static beams. The lengths of attachment were measured using pretreatment CT images at the lung window. Cumulative incidence rates were calculated using Kaplan-Meier curves, and univariate and multivariate analyses for in-field tumor control, locoregional control (LRC), freedom from distant metastasis and freedom from progression (FFP) were performed using a Cox proportional hazards model.
  
  
  RESULTS
  Of the 90 tumors, 42 tumors were attached to the pleura (median, 14.7 mm; range, 4.3-36.0 mm), 21 tumors had pleural indentation and 27 tumors had no attachment. The median follow-up period for survivors was 46.1 months. The 3-year in-field control, LRC, FFP and overall survival rates were 91.2%, 75.3%, 63.8% and 68.6%, respectively. SBRT dose and tumor diameter were independently significant predictors of in-field control (p = 0.02 and p = 0.04, respectively). Broad attachment to the pleura, the length being more than 14.7 mm, was a negative independent predictor of LRC and FFP (p = 0.02 and p = 0.01, respectively).
  
  
  CONCLUSIONS
  Pleural attachment status on a pretreatment CT image might be an important predictor of LRC and FFP.
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. t.yamamoto@rad.med.tohoku.ac.jp.
authors.forename: Takaya
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. kadoya.n@rad.med.tohoku.ac.jp.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kadoya
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. guldoktu@yahoo.co.jp.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Shirata
authors.affiliation: Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan. koto@nirs.go.jp.
authors.forename: Masashi
authors.initials: M
authors.lastname: Koto
authors.affiliation: Radiation Technology, Tohoku University Hospital, Sendai, Japan. kiyokazu-sato@rad.hosp.tohoku.ac.jp.
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Sato
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. harumatsu2001@yahoo.co.jp.
authors.forename: Haruo
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authors.lastname: Matsushita
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. sugatosi772288@yahoo.co.jp.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Sugawara
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. reirei513@hotmail.com.
authors.forename: Rei
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authors.lastname: Umezawa
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. satoharuapple@yahoo.co.jp.
authors.forename: Masaki
authors.initials: M
authors.lastname: Kubozono
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. y02614111@yahoo.co.jp.
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Ishikawa
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. maiko.kozumi@gmail.com.
authors.forename: Maiko
authors.initials: M
authors.lastname: Kozumi
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. noriyoshi.08.25@gmail.com.
authors.forename: Noriyoshi
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authors.lastname: Takahashi
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. takedak41@yahoo.co.jp.
authors.forename: Kengo
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. ykhasedo@gmail.com.
authors.forename: Yu
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authors.lastname: Katagiri
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. takedak41@yahoo.co.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Department of Radiation Oncology, Tohoku University School of Medicine, Sendai, Japan. kjingu-jr@rad.med.tohoku.ac.jp.
authors.forename: Keiichi
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authors.lastname: Jingu
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010994:Pleura / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies; D015996:Survival Rate; D014057:Tomography, X-Ray Computed / Q000379:methods