Association Between Adjuvant Chemotherapy and Nephrotoxicity and Kidney Function Monitoring in Elderly Breast Cancer Patients

Abstract

<italic>Background</italic>: Chronic kidney disease (CKD) and cancer are major public health problems in the elderly population. In elderly cancer patients, little is known about chemotherapy-related nephrotoxicity or patterns of CKD screening. The purpose of this dissertation was to evaluate the association between adjuvant chemotherapy (CHEMO) and risks of acute kidney injury (AKI) and CKD and rate of CKD screening in elderly women diagnosed with stages I-III breast cancer. <italic>Methods</italic>: The study was a 1:1 individually matched, retrospective cohort design using Surveillance, Epidemiology, and End Results (SEER)-Medicare linked data. Matching was performed at the day of CHEMO initiation based on propensity score. The assembled matched cohorts were used in the analyses for all three objectives with different follow-up periods and statistical methods for each objective. HASH(0x307f974) <italic>Results</italic>: A total of 28,048 patients were included. CHEMO was associated with a 2.7-fold increased risk of AKI within 6 months after initiation (HR 2.7, 95% CI 1.8-4.1). To find a possible explanation to this association, the distribution of other diseases coded on hospital claims for AKI was examined and showed that septicemia occurred in 40% of CHEMO treated patients with AKI and in only 17% of untreated patients with AKI. No significant association was found between CHEMO and risk of CKD in the maximum 18 years follow-up (HR 1.00, 95% CI 0.93-1.07). The rate of CKD screening after treatment completion was low regardless of CHEMO status. HASH(0x2faf9d4) <italic>Conclusion</italic>: CHEMO is associated with increased risk of AKI. This association may be partially explained by septicemia caused by infection/neutropenia due to use of myelosuppressive chemotherapeutic agents, which highlights the importance of preventing serious complications of CHEMO in preventing AKI. The finding of no association between CHEMO and risk of CKD may not suggest a late nephrotoxic effect of chemotherapeutic agents commonly used to treat breast cancer in the adjuvant setting, or provide evidence to recommend a clinical practice guideline for CKD screening specifically in elderly breast cancer patients treated with CHEMO. Future studies of CKD as a late effect of cancer treatment for other solid tumors commonly treated with known or potential nephrotoxic agents are warranted.