Cancer surveillance imaging: Does repeated iodinated contrast exposure impact long-term kidney function?

Contrast-induced nephropathy is a well-recognized acute complication in cancer patients, but the long-term effects of repeated contrast exposure are not known. We analyzed the association of the number of contrast-enhanced computed tomography (CECT) examinations and other clinical factors with decline in estimated glomerular filtration rate (eGFR) in colorectal cancer survivors. We retrospectively queried a prospective surgical colorectal cancer database to identify patients with stage I or II cancer who underwent resection in 2007 - 2013 and were alive for at least 3 years. eGFR was calculated before and 3 years after the surgery with ≥ 20% decline relative to baseline defined as significant and used as the primary outcome. The association of clinical factors with the primary outcome was analyzed using logistic regression. Only 256 patients with the median follow-up of 65 months had sufficient clinical data for analysis. Median eGFR decline at follow-up was 3.0 mL/min/1.73m or 4% change from baseline. 47 patients (18%) had ≥ 20% reduction in eGFR, which was not associated with the number of CECT examinations. Multivariable analysis demonstrated that increasing age (OR, 1.03; 95% CI, 1.00 - 1.06), presence of diabetes (OR, 2.33; 95% CI, 1.18 - 4.61), and longer operation time (OR, 1.04; 95% CI, 1.01 - 1.07) were independently associated with a higher likelihood of ≥ 20% eGFR decline at 3 years. Older age, diabetes, and longer operating time, but not cumulative contrast exposure were found to be associated with worse long-term renal outcomes following surgical resection in patients with early-stage colorectal cancer who survived 3 years.