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

This is the first known study examining renal function following stereotactic body radiotherapy (SBRT) for pancreatic head adenocarcinoma. Thirty-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. The median total kidney volume was 355 cm . Median dosimetric values were as follows: V5 (209 cm ), V10 (103 cm ), V15 (9 cm ), V20 (0 cm ), V25 (0 cm ); and mean (6.7 Gy) & maximum kidney dose (18.3 Gy). Median GFR change was -23 (range, -105 to 25) mL/min/1.73 cm . Of all dosimetric parameters, only V5 was significantly associated with changes in GFR (Pearson r = -0.40, p = 0.012). In patients with V5