Adverse outcomes have been associated with delays in the administration of adjuvant chemotherapy among breast cancer patients. We evaluate the determinants and outcomes associated with delays in time to chemotherapy (TTC) in a large cohort of older breast cancer patients.
We used the NCI-Surveillance Epidemiology and End Results (SEER) and Texas Cancer Registry (TCR)-Medicare linked data bases to identify patients ≥66 years old diagnosed with localized or regional breast cancer between 2001-2011. All patients received chemotherapy within 9 months of surgery. Delayed TTC was defined as > 90 days. Multivariable logistic regression was used to identify predictors of treatment delay. A Cox Proportional Hazards model was fit to determine the association between treatment delay, overall survival (OS) and breast cancer specific survival (BCSS).
25,096 patients were included, of them 2,676 (10.7%) had a TTC >90 days. In multivariable analysis factors associated with delays in TTC were: recent year of diagnosis (2011 vs 2001 OR = 1.31; 95%CI 1.03-1.67), older age (76-80 vs 66-70 OR = 1.51; 95%CI 1.33-1.72), black race (OR = 1.35; 95%CI 1.14-1.58), having state buy-in (as an indicator of poverty) (OR = 1.27; 95%CI 1.1-1.47), comorbidities (Charlson score 1 OR = 1.23;95%CI 1.09-1.37; score 2 OR = 1.57; 95%CI 1.37-1.81), mastectomy (OR = 1.49; 95%CI 1.33-1.67), mastectomy with immediate reconstruction (OR = 1.85; 95%CI 1.37-2.48), Oncotype DX testing (OR = 1.68; 95%CI 1.4-2.02), mastectomy >30 days after the initial surgery (OR = 16.91; 95%CI 12.07-23.68), brachytherapy (OR = 4.11; 95%CI 3.17-5.34) and whole breast radiation prior to chemotherapy (OR = 31.9; 95%CI 28.05-36.49). After adjusting for potential confounders, patients with TTC >90 days had worse OS (HR = 1.37; 95%CI 1.27-1.48) and BCSS (HR = 1.34; 95%CI 1.19-1.51).
A delay in adjuvant chemotherapy administration >90 days is associated with adverse outcomes among older breast cancer patients. Determinants of delays were sociodemographic in nature, related to patient’s characteristics and to treatment received. Every effort should be made to identify vulnerable patients and to administer chemotherapy in a timely manner.
Clinical trial identification
Legal entity responsible for the study
The University of Texas MD Anderson Cancer Center
Susan G. Komen, CIPRIT
All authors have declared no conflicts of interest.