Association between adjuvant chemotherapy and risk of acute kidney injury in elderly women diagnosed with early-stage breast cancer.

PURPOSE: We studied elderly Medicare enrollees newly diagnosed with early-stage breast cancer to examine the association between adjuvant chemotherapy and acute kidney injury (AKI).

METHODS: Using the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database, we conducted a retrospective cohort study including women diagnosed with stages I-III breast cancer at ages 66-89 years between 1992 and 2007. We performed one-to-one matching on time-dependent propensity score on the day of adjuvant chemotherapy initiation within 6 months after the first cancer-directed surgery based on the estimated probability of chemotherapy initiation at each day for each patient, using a Cox proportional hazards model. We estimated the cumulative incidence of AKI using Kaplan-Meier methods. We used Cox proportional hazards models to evaluate the association between chemotherapy and the risk of AKI, and compared the risk among major chemotherapy types.

RESULTS: The study included 28,048 women. The 6-month cumulative incidence of AKI was 0.80% for chemotherapy-treated patients, compared with 0.30% for untreated patients (P < 0.001). Adjuvant chemotherapy was associated with a nearly threefold increased risk of AKI [hazard ratio (HR) 2.73; 95% CI 1.8-4.1]. Compared with anthracycline-based chemotherapy, the HRs (95% CIs) were 1.66 (0.94-2.91), 0.88 (0.53-1.47), and 1.15 (0.57-2.32) for taxane-based, CMF, and other chemotherapy, respectively.

CONCLUSION: Our findings showed that adjuvant chemotherapy was associated with increased risk of AKI in elderly women diagnosed with early-stage breast cancer. The risk seemed to vary by regimen type, but the differences were not statistically significant.