title: Impact of stereotactic radiotherapy on kidney function in primary renal cell carcinoma: Establishing a dose-response relationship.
abstract: OBJECTIVE
  To evaluate renal dysfunction after stereotactic ablative body radiotherapy (SABR) for inoperable primary renal cell carcinoma (RCC) using nuclear medicine assessments.
  
  
  METHODS
  In a prospective clinical trial, patients received single fraction renal SABR (26 Gy) for tumours <5 cm, or fractionated SABR (3 × 14 Gy) for tumours ⩾5 cm. Global and regional glomerular filtration rate (GFR) was calculated through (51)Cr-EDTA and (99m)Tc-DMSA SPECT/CT, respectively, at baseline and post-treatment (14, 90 days and at 1-year). Regional loss in function was correlated to the absolute and biologically effective doses (BED) delivered.
  
  
  RESULTS
  In 21 patients the mean (range) tumour size was 48 mm (21-75 mm). The mean ± SD GFR at baseline was 52 ± 24 ml/min. Net change in mean GFR was +0.6 ± 11.3, +3.2 ± 14.5 and -8.7 ± 13.4 ml/min (p=0.03) at 2 weeks, 3 months and 1 year, respectively. For every 10 Gy of physical dose delivered, an exponential decline in affected kidney GFR was observed at 39% for 26 Gy/1 fraction and 25% for 42 Gy/3 fractions. When normalised to BED3Gy, the dose-response relationship for each treatment prescription was similar with a plateau beyond 100 Gy. The R50% conformity index correlated with GFR loss (p=0.04). No patient required dialysis.
  
  
  CONCLUSIONS
  SABR results in clinically acceptable and dose-dependent renal dysfunction at 1-year. Sparing functional kidney from high-dose regions (>50% isodoses) may help reduce risk of functional loss.
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Australia. Electronic address: shankar.siva@petermac.org.
authors.forename: Shankar
authors.initials: S
authors.lastname: Siva
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Australia.
authors.forename: Price
authors.initials: P
authors.lastname: Jackson
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Australia.
authors.forename: Tomas
authors.initials: T
authors.lastname: Kron
authors.affiliation: Department of Biostatistics and Clinical Trials, Peter MacCallum Cancer Centre, Australia.
authors.forename: Mathias
authors.initials: M
authors.lastname: Bressel
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Australia; Department of Radiology, University of Melbourne, Australia.
authors.forename: Eddie
authors.initials: E
authors.lastname: Lau
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Hofman
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Shaw
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Australia.
authors.forename: Sarat
authors.initials: S
authors.lastname: Chander
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Australia.
authors.forename: Daniel
authors.initials: D
authors.lastname: Pham
authors.affiliation: Division of Cancer Surgery, Peter MacCallum Cancer Centre, Australia.
authors.forename: Nathan
authors.initials: N
authors.lastname: Lawrentschuk
authors.affiliation: Department of Surgery, University of Melbourne, Australia.
authors.forename: Lih-Ming
authors.initials: LM
authors.lastname: Wong
authors.affiliation: Division of Cancer Surgery, Peter MacCallum Cancer Centre, Australia.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Goad
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Australia.
authors.forename: Farshad
authors.initials: F
authors.lastname: Foroudi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002292:Carcinoma, Renal Cell / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005919:Glomerular Filtration Rate / Q000528:radiation effects; D006801:Humans; D007668:Kidney / Q000503:physiopathology* / Q000528:radiation effects* / Q000601:surgery; D007680:Kidney Neoplasms / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D015899:Tomography, Emission-Computed, Single-Photon
keywords: Creatinine; Nephron sparing; Normal tissue toxicity; RCC; SABR; SBRT