Renal atrophy secondary to chemoradiotherapy of abdominal malignancies

Purpose: To identify factors predictive of renal atrophy after chemoradiotherapy of gastrointestinal malignancies. Methods and Materials: Patients who received chemotherapy and abdominal radiotherapy (RT) between 2002 and 2008 were identified for this study evaluating change in kidney size and function after RT. Imaging and biochemical data were obtained before and after RT in 6-month intervals. Kidney size was defined by craniocaudal measurement on CT images. The primarily irradiated kidney (PK) was defined as the kidney that received the greater mean kidney dose. Receiver operating characteristic (ROC) curves were generated to predict risk for renal atrophy. Results: Of 130 patients, median age was 64 years, and 51.5% were male. Most primary disease sites were pancreas and periampullary tumors (77.7%). Median follow-up was 9.4 months. Creatinine clearance declined 20.89%, and size of the PK decreased 4.67% 1 year after completion of chemoradiation. Compensatory hypertrophy of the non-PK was not seen. Percentage volumes of the PK receiving ≥10 Gy (V ₁₀), 15 Gy (V₁₅), and 20 Gy (V₂₀) were significantly associated with renal atrophy 1 year after RT (p = 0.0030, 0.0029, and 0.0028, respectively). Areas under the ROC curves for V₁₀, V₁₅, and V₂₀ to predict >5% decrease in PK size were 0.760, 0.760, and 0.762, respectively. Conclusions: Significant detriments in PK size and renal function were seen after abdominal RT. The V₁₀, V₁₅, and V₂₀ were predictive of risk for PK atrophy 1 year after RT. Analyses suggest the association of lower-dose renal irradiation with subsequent development of renal atrophy.