br On long term follow
On long-term follow-up, more than one-fifth of the patients developed renal impairment and/or proteinuria. The occurrence of AKI was significantly associated with the development of long-term renal impairment, in accor-dance with a well-known finding that AKI is a risk factor of CKD.10 In particular, the experience of multiple episodes of AKI, but not the onset time or the severity of AKI, was a risk factor of long-term renal impairment. Notably, among the risk factors of long-term renal impairment, the recurrence and, thus, the number of AKI episodes may be the only potentially modifiable risk factor. It is also notable that patients with low initial eGFR was significantly associ-ated with the development of long-term renal impairment. Close monitoring of renal function after the course of treatment in these patients may be helpful to mitigate poor outcomes. Although Wilms tumor was ranked eighth regarding the development of AKI among the 17 different cancer types in our study, a high proportion (37%) of patients with Wilms tumor developed renal impairment in the long-term follow-up (Table II). Moreover, nephrectomy was found to be an independent risk factor of long-term renal impairment. Decreased number of nephrons has direct effect on decreased renal function,
although it GW311616 is partly compensated by the increase in GFR per nephron.31,32 One study reported that one-half of the
nephrectomized patients with Wilms tumor or NBL had a final eGFR of less than 90 mL/minute/1.73 m2.33 Thus, close monitoring of renal function and applications of nephroprotective measures are necessary in these patients. However, most of the patients had only mild kidney dysfunction, partly because of the lack of enough follow-up time. Our data should be interpreted with caution because the complete final eGFR data was missing in a large portion of survivors and the patients with this data tended to be those who have undergone prolonged or intensive treatment courses such as HSCT because of high
cancer stage or relapse. The reported prevalence of proteinuria in cancer survivors is 3.2%.34 In our study, a total of 8.2% of the patients developed proteinuria. However, our results may have been biased and overestimated because patients who have not experienced clinically overt renal insults may not have had their urinalysis followed-up routinely. Also, as it is the result from random urinalysis, much of these findings may be due to the benign proteinuria which does not require specific management. Nonetheless, because proteinuria is a well-known risk factor of CKD progression, this subset of patients might need further evaluation to detect pathologic proteinuria in early stage to improve long-term renal outcome.
This study has the inherent limitation that it was a retrospective medical chart review and single center study. The results should be interpreted with caution because the study population may have been a biased group of patients because of our institutional status as a referral center for pediatric patients in South Korea. In addition, the evaluation of AKI in this study is not fully comprehensive because the criterion involving urine output was not included. Also, defining impaired renal function as eGFR less than 90 mL/minute/1.73 m2 may be imprecise given the limited accuracy of Cr based eGFR in patients with mildly impaired kidney function, although it was partly due to the lack of patients with severely impaired kidney function for statistical analysis. Furthermore, not all of the factors that may have affected the development of AKI and the long-term renal outcome were sufficiently analyzed. For instance, the study did not evaluate the cancer stage, all the chemotherapeutic agents and regimens used (eg, dosages and schedules), or all the possibly nephrotoxic medications (eg, antimicrobial agents).