Quantification of renal function following stereotactic body radiotherapy for pancreatic cancer: secondary dosimetric analysis of a prospective clinical trial

Abstract

BackgroundThis is the first known study examining renal function following stereotactic body radiotherapy (SBRT) for pancreatic head adenocarcinoma.MethodsThirty-eight borderline-resectable/unresectable patients, part of an ongoing prospective trial, underwent 3 cycles of gemcitabine/5-fluorouracil followed by SBRT (5 daily fractions of 5/6/7/8 Gy) and concurrent nelfinavir. Thereafter, in resectable cases, surgery was performed within 4–8 weeks. The last available pre-SBRT creatinine was recorded, along with the highest post-SBRT value. Glomerular filtration rate (GFR) was calculated by the commonly-utilized Modification of Diet in Renal Disease formula. GFR decline was defined as the post-SBRT nadir GFR minus the pre-SBRT GFR. Correlations with the V5–V30, and mean/maximum kidney doses was performed. Statistics included Pearson correlation, Mann-Whitney, and Fisher’s exact tests.ResultsThe median total kidney volume was 355 cm3. Median dosimetric values were as follows: V5 (209 cm3), V10 (103 cm3), V15 (9 cm3), V20 (0 cm3), V25 (0 cm3); and mean (6.7 Gy) & maximum kidney dose (18.3 Gy). Median GFR change was −23 (range, −105 to 25) mL/min/1.73 cm2. Of all dosimetric parameters, only V5 was significantly associated with changes in GFR (Pearson r = −0.40, p = 0.012). In patients with V5 < 210 cm3, median GFR change was −11.8 mL/min/1.73 cm2, as compared with −37.1 mL/min/1.73 cm2 change in those with V5 ≥ 210 cm3 (p = 0.02). A GFR change < −23 mL/min/1.73 cm2 was observed in 6/20 (30%) patients with V5 < 210 cm3, versus 15/18 (83%) of those with V5 ≥ 210 cm3. Patients with V5 ≥ 210 cm3 were over ten times as likely to have GFR change < −23 mL/min/1.73 cm2 (p = 0.003). Using linear regression, GFR change ≈ −0.1748 × V5(cm3) + 8.63.ConclusionsIn the first known analysis of renal function after pancreatic SBRT, evaluating patients on a prospective study, V5 ≥ 210 cm3 was associated with a post-SBRT GFR decline of >23 mL/min/1.73 cm2. If V5 is kept <210 cm3, median GFR decline was only 11.8 mL/min/1.73 cm2. Further validation is needed to ascertain definite dose-volume parameters and examine late renal decline.

Stereotactic body radiation therapy for adrenal gland metastases: Outcomes and toxicity

“…Retrospective studies have reported renal functional compromise after SBRT that was directed to the kidneys and pancreatic tumors, but to our knowledge, this is the first study to address renal function decline after SBRT that targets the adrenal glands. 65 , 66 , 67 , 68 Siva et al analyzed 21 patients with renal cell carcinoma who were treated with SBRT and assessed the eGFR through 51 Cr-EDTA and 99m Tc-DMSA SPECT/CT images. 65 The researchers reported a mean eGFR drop of 3.2 ± 14.5 ml/min/1.73 m 2 at 3 months and identified a dose-response relationship between eGFR change and SBRT doses.…”

Renal atrophy following gated delivery of stereotactic ablative radiotherapy to adrenal metastases

“…The available renal OAR constraints were largely derived from published experience in children and adults treated using conventionally fractionated radiotherapy. Only recently has renal function data emerged from patients treated using SABR [7,8]. After SABR to primary renal tumors to a dose of 42 Gy in three fractions, each 10 Gy increase in physical dose led to an exponential decline of 25% in glomerular filtration rates (GFR) [7].…”

“…After SABR to primary renal tumors to a dose of 42 Gy in three fractions, each 10 Gy increase in physical dose led to an exponential decline of 25% in glomerular filtration rates (GFR) [7]. For pancreatic tumors, the renal volumes receiving 5 Gy during SABR were significantly associated with changes in GFR, a finding related to steep dose fall-offs outside the pancreas [8]. However, SABR delivery during free breathing may lead to less accurate estimates of doses to a mobile OAR.…”

Phase I trial of concurrent stereotactic body radiotherapy and nelfinavir for locally advanced borderline or unresectable pancreatic adenocarcinoma

“…Additionally, neoadjuvant treatment better favors the delivery of stereotactic body radiation therapy (SBRT), also known as stereotactic ablative radiotherapy, which is a highly conformal modality that affords low doses to surrounding organs-at-risk [7][8]. It has the major advantages of avoiding a protracted interval from diagnosis to surgery, along with increased patient convenience and enhanced cost-effectiveness [9].…”