title: Renal atrophy after stereotactic body radiotherapy for renal cell carcinoma.
abstract: BACKGROUND
  Renal atrophy is observed in an irradiated kidney. The aim of this study was to determine dose-volume histogram parameters and other factors that predict renal atrophy after 10-fraction stereotactic body radiotherapy (SBRT) for primary renal cell carcinoma (RCC).
  
  
  METHODS
  A total of 14 patients (11 males, 3 females) who received SBRT for RCC at Tohoku University Hospital between April 2010 and February 2014 were analyzed. The median serum creatinine level was 1.1 mg/dl and two patients had a single kidney. Nine patients were implanted with fiducial markers. The median tumor diameter was 30 mm. SBRT was delivered at 70 Gy in 10 fractions for 7 tumors, at 60 Gy in 10 fractions for 2 tumors, and at 50 Gy in 10 fractions for 5 tumors with 6 and/or 15 MV X-ray using 5 to 8 multi-static beams. Renal atrophy was assessed using post-SBRT CT images after 12-24 months intervals. Correlations were examined by Spearman rank correlation analysis. Differences between two groups were evaluated by the Mann-Whitney test, and pairwise comparisons were made by the Wilcoxon signed-rank test.
  
  
  RESULTS
  The median tumor volume shrunk from 14.8 cc to 10.6 cc (p = 0.12), and the median irradiated kidney volume changed from 160.4 cc to 137.1 cc (p < .01). The median peak creatinine level was 1.6 mg/dl after treatment (p < .01). Percentage volumes of the irradiated kidney receiving at least 10 Gy (V10, p = 0.03), V20 (p < .01), V30(p < .01), V40 (p = 0.01), mean irradiated kidney dose (p < .01), and magnitude of overlap between PTV and kidney volume (p = 0.03) were significantly correlated with post-treatment irradiated kidney volume in percent, and V20-V30 had strong correlation (r < -0.70, p < .01). Patients with implanted fiducial markers showed a significantly lower ratio of renal atrophy (p = 0.02).
  
  
  CONCLUSIONS
  Significant renal atrophic change was observed. Dose distribution of SBRT at 20-30 Gy had a strong correlation with renal atrophy when irradiation was performed in 10 fractions.
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan. t.yamamoto@rad.med.tohoku.ac.jp.
authors.forename: Takaya
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kadoya
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Haruo
authors.initials: H
authors.lastname: Matsushita
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Rei
authors.initials: R
authors.lastname: Umezawa
authors.affiliation: Radiation Technology, Tohoku University Hospital, Sendai, Japan.
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Sato
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Kubozono
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Kengo
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Ishikawa
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Maiko
authors.initials: M
authors.lastname: Kozumi
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Noriyoshi
authors.initials: N
authors.lastname: Takahashi
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Katagiri
authors.affiliation: Department of Radiology, School of Medicine, University of Yamanashi, Yamanashi, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Onishi
authors.affiliation: Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Jingu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001284:Atrophy / Q000209:etiology*; D002292:Carcinoma, Renal Cell / Q000150:complications / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007680:Kidney Neoplasms / Q000150:complications / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011832:Radiation Injuries / Q000209:etiology*; D011874:Radiometry; D016634:Radiosurgery / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D047368:Tumor Burden
keywords: Renal atrophy; Renal cell cancer; Renal remodeling; SRT; Stereotactic radiotherapy