Abstract P3-07-29: Association between adjuvant chemotherapy and risk of acute kidney injury in elderly women diagnosed with early stage breast cancer
Authors: Li Shuling , Liu Jiannong , Virnig Beth A , Collins Allan J 
Published: May 2015

Abstract
Background: Acute kidney injury (AKI) is a serious complication of cancer and its treatment, causing delay or interruptions in cancer therapy and increased risk of adverse outcomes including premature death. Little is known from large population-based cohort studies about the association between chemotherapy (chemo) and risk of AKI in elderly cancer patients (pts).
Methods: This retrospective cohort study used the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare data. Women diagnosed with stages I-III breast cancer (BC) at ages 66-89 years between 1992-2007 were included. We performed 1-1 sequential matching on time-dependent propensity score on the day of adjuvant chemo initiation within 6 months (mos) after the first surgery. Follow-up (F/U) began on the matching date and ended at AKI occurrence, chronic kidney disease diagnosis, death, change in enrollment status, or 6 mos after the matching date. For pts in the matched untreated cohort, F/U time was also censored at chemo initiation. Chemo was identified in claims through billing codes indicating drugs or administration. Regimens of interest included anthracyclines (A), CMF, taxanes (T, no anthracyclines), and others. AKI was identified in hospital claims. The cumulative incidence of AKI was assessed using the Kaplan-Meier method. The association between adjuvant chemo and risk of AKI was evaluated using a Cox proportional hazards model. The analyses were repeated by regimen type.
Results: The matched study cohorts included 28,048 pts. The mean (standard deviation) F/U time was 6.0 (0.8) mos for the chemo cohort and 4.3 (2.5) mos for the matched no-chemo cohort. The cumulative incidence of AKI at mos 1, 3, and 6 was 0.24%, 0.50%, and 0.80% for pts receiving chemo, compared with 0.05%, 0.17%, and 0.30% for no-chemo pts (P&lt;0.001). Adjuvant chemo was associated with a 2.7-fold increased risk of AKI (HR 2.7, 95% CI 1.8-4.1; P&lt;0.001), despite a very low overall incidence rate (16 and 6 per 1000 person-years in chemo and no-chemo pts, respectively). Further examination of distribution of other diseases coded on hospital claims in AKI pts showed that septicemia occurred in 40% of chemo-treated pts with AKI and in only 17% of untreated pts with AKI. Of chemo-treated pts, 53%, 31%, 7%, and 8% received an A-based, a CMF, a T-based, and other regimens, respectively. Each regimen was significantly associated with increased risk of AKI, with the strongest association for a T-based regimen (HR 4.2, 95% CI 2.2-7.8), the weakest for a CMF regimen (HR 2.2, 95% CI, 1.3-3.8), and intermediate associations for an A-based regimen (HR 2.5, 95% CI 1.6-4.1) and others (HR 3.0, 95% CI 1.5-6.2), but the effect of these regimens did not significantly differ from each other.
Conclusion: Adjuvant chemo is associated with increased risk of AKI in elderly women diagnosed with early stage BC. This association may be partially explained by septicemia caused by infection/neutropenia due to use of myelosuppressive chemotherapeutic agents, highlighting the importance of preventing serious complications of chemo in preventing AKI.
Citation Format: Shuling Li, Jiannong Liu, Beth A Virnig, Allan J Collins. Association between adjuvant chemotherapy and risk of acute kidney injury in elderly women diagnosed with early stage breast cancer [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P3-07-29.