Change in creatinine clearance over time following upper abdominal irradiation: a dose-volume histogram multivariate analysis.

Objectives: To investigate the change in creatinine clearance (CrCl) over time following upper abdominal radiation utilizing a dose-volume histogram (DVH) multivariate analysis.

Methods: The study population included 125 patients with gastrointestinal malignancy treated with abdominal radiation therapy at our institution between 1994 and 2006, with available creatinine and DVH information. Kidney dose-volume data collected included mean kidney dose, volume of kidney irradiated, V5, V10, and V20 of total kidney volume, and number of mL of kidney greater than and less than 20 Gy.

Results: With a median follow-up of 2.4 years, and a mean kidney dose of 16.2 Gy, a significant correlation between decrease in CrCl and irradiated kidney volume observed was noted for all DVH parameters. The strongest correlations were found when using V5, V10, and number of mL of kidney treated to greater than 20 Gy. There was no significant change in number of antihypertensive medications taken by patients over time, and no relationship between outcome variables and pre-existing comorbidities.

Conclusions: This is the first study that we are aware of comparing DVH data with measurement of renal toxicity. We show significant correlations between dose and volume irradiated and decline in renal function. This will be clinically useful when determining a treatment plan for patients with borderline preradiation CrCl and provides evidence that minimizing radiation to the kidney could have important clinical ramifications.