6591 Background: The objective of this study is to understand the impact of timely radiotherapy on disease-free survival (DFS) in early breast cancer patients ages 65 and above. Methods: The study population is women diagnosed from 1991–1999 in the linked SEER-Medicare database who underwent breast-conserving surgery and radiotherapy within 6 months of diagnosis. Median followup varies from 4 years for ductal carcinoma in situ (DCIS)(n=1,185) to 5 years for Stage 1 disease (n=7,481), and ranges from 0–11 years. Descriptive and proportional hazards analysis of this longitudinal cohort were conducted. Covariates include age, race, poverty, marital status, comorbidity, rurality, radiation completion and delay, elapsed time since diagnosis, comedo necrosis histology (DCIS only), and chemotherapy receipt (Stage 1 only). Subjects were censored at end of followup (including enrolling in Medicare managed care from Medicare fee-for-service) or death. Treatment delay is defined as radiotherapy beginning 8+ weeks post-surgery without chemotherapy or 4+ weeks after chemotherapy ends; other definitions also were explored. Radiotherapy is considered complete if the patient received greater than 16/22 of expected treatments, based on scientific literature. Results: DFS is negatively associated with radiation delay (OR=1.24, p=0.003 for Stage 1; OR=1.40, p=0.054 for DCIS) and Klabunde's inpatient comorbidity index (OR=1.32, p=0.004 for Stage 1; OR=1.66, p=0.065 for DCIS). Additional analyses suggest that a longer delay of 12+ weeks post-surgery (16+ weeks post-chemotherapy) further reduces DFS (OR=4.66, p<0.0001 for Stage 1; OR=12.4, p<0.0001 for DCIS). Non-white women with Stage 1 disease are more likely to delay radiotherapy (p<0.0001), but are not more likely to have worse outcomes (p>0.3). Conclusions: Delayed initiation of radiation therapy is associated with decreased DFS following radiotherapy for early breast cancer and DCIS. Non-white race is associated with delay, but not reduced DFS. Programs targeting referring physicians and patients should be developed to promote timely receipt of radiotherapy by early breast cancer patients, thereby reducing the risk of adverse health outcomes. No significant financial relationships to disclose.
First prospective multicenter Italian study on the impact of the 21-gene recurrence score® (RS) in adjuvant clinical decisions for ER + /HER2- early breast cancer patients
