Abstract P3-07-30: Association between adjuvant chemotherapy and risk of chronic kidney disease 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: Chronic kidney disease (CKD) and cancer are major public health problems in the elderly population. With the development of cancer screening and efficacious treatments including chemotherapy (chemo), the number of cancer survivors has been increasing. In elderly cancer patients (pts), little is known about CKD as a late effect of chemo. This study examined the association between adjuvant chemo and risk of CKD in elderly women diagnosed with early stage breast cancer (BC).
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 preformed 1-1 sequential matching on time-dependent propensity score on the day of adjuvant chemo initiation within 6 months after the first surgery. Follow-up (F/U) began on the matching date and ended at CKD diagnosis, death, change in enrollment status, or December 31, 2009. 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. CKD was identified through diagnosis codes in Medicare claims. The cumulative incidence of CKD was assessed using the Kaplan-Meier method. The association between adjuvant chemo and risk of CKD 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 5.1 (3.4) years for the chemo cohort and 3.3 (3.6) years for the matched no-chemo cohort. CKD rate (standard error) was 29.0 (0.6) and 29.3 (0.8) per 1000 patient-years in chemo and no-chemo pts, respectively. Overall, there was no significant difference in the cumulative incidence of CKD between the two cohorts (chemo vs. no-chemo, 47.2% vs. 49%; P=0.91). Adjuvant chemo was not associated with increased risk of developing CKD (HR 1.00, 95% CI 0.93-1.07). Of chemo-treated pts, 53%, 31%, 7%, and 8% received an A-based, a CMF, a T-based, and other regimens, respectively. Though the association between adjuvant chemo and risk of CKD varied across regimen types, these associations were not statistically significant (Table).
Regimen TypeTotal, nMean (SD) F/U time, yearsRate of CKD (1000 pt-yrs)Adjusted HR (95% CI)*No chemo140243.3 (3.6)29.3ReferenceA-based74654.8 (3.0)27.70.96 (0.88-1.04)CMF43896.0 (3.9)29.11.04 (0.95-1.14)T-based10302.8 (1.8)39.40.91 (0.74-1.12)Other11405.1 (4.0)31.21.04 (0.89-1.22)*Adjusted for patient baseline characteristics and trastuzumab use
Conclusion: Adjuvant chemo in elderly women with BC may not impose additional risk for CKD. This finding suggests that patients’ underlying risk factors for CKD such as diabetes, hypertension, etc. should be considered in the discussions between clinicians and pts regarding potential risk of CKD development after chemo treatment and choice of chemo treatment.
Citation Format: Shuling Li, Jiannong Liu, Beth A Virnig, Allan J Collins. Association between adjuvant chemotherapy and risk of chronic kidney disease 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 P3-07-30.