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).
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.
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).
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.
Radiation oncology (London, England). 2016 May 26*** epublish ***
Takaya Yamamoto, Noriyuki Kadoya, Ken Takeda, Haruo Matsushita, Rei Umezawa, Kiyokazu Sato, Masaki Kubozono, Kengo Ito, Yojiro Ishikawa, Maiko Kozumi, Noriyoshi Takahashi, Yu Katagiri, Hiroshi Onishi, Keiichi Jingu
Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan. ., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan., Radiation Technology, Tohoku University Hospital, Sendai, Japan., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan., Department of Radiology, School of Medicine, University of Yamanashi, Yamanashi, Japan., Department of Radiation Oncology, Graduate School of Medicine, University of Tohoku, Sendai, Japan.