title: Relationship between the consolidation to maximum tumor diameter ratio and outcomes following stereotactic body radiotherapy for stage I non-small-cell lung cancer.
abstract: OBJECTIVE
  We investigated whether the ratio of the maximum diameter of consolidation to the maximum tumor diameter (consolidation/tumor ratio, CTR) predicted the outcomes of patients who received stereotactic body radiotherapy (SBRT) for non-small-cell lung cancer (NSCLC).
  
  
  METHODS
  Between 2005 and 2014, 237 patients with stage I NSCLC were treated with SBRT, receiving 48 Gy in 4 fractions. Of these patients, those who received pretreatment thin section computed tomography were selected for this analysis. The relationship between the CTR and outcomes (local control [LC], disease-free survival [DFS], and overall survival [OS]) was analyzed.
  
  
  RESULTS
  One hundred and fifty-five patients were eligible. The median follow-up time was 34.7 months (range, 1.2-109.8). In the CTR<0.5, CTR 0.5-<1, and CTR=1 groups, 0, 2, and 12 patients experienced local recurrences, respectively. Three-year DFS and OS rates were 96.7% and 87.5% in the CTR<0.5 group, 85.1% and 81.1% in the CTR 0.5-<1 group, and 63.3% and 70.1% in the CTR=1 group, respectively. In multivariate analysis, CTR was the only significant predictor of DFS (P<0.001).
  
  
  CONCLUSIONS
  The CTR effectively predicts DFS after SBRT in NSCLC patients.
authors.affiliation: Radiation Oncology Department, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, Tokyo, Japan. Electronic address: yuichiro.tsurugai@jfcr.or.jp.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Tsurugai
authors.affiliation: Radiation Oncology Department, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, Tokyo, Japan.
authors.forename: Takuyo
authors.initials: T
authors.lastname: Kozuka
authors.affiliation: Clinical Trial Department, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, Tokyo, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ishizuka
authors.affiliation: Radiation Oncology Department, Cancer Institute Hospital of the Japanese Foundation for Cancer Research, Tokyo, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Oguchi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology* / Q000601:surgery*; D008297:Male; D009367:Neoplasm Staging; D016634:Radiosurgery; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
keywords: Consolidation/tumor ratio; Ground-glass opacity; Non-small cell lung cancer; Stereotactic body radiotherapy