Cost implications of delayed radiotherapy for early stage breast cancer

6549 Background: Delayed radiotherapy (RT) for early invasive breast cancer has been shown to increase recurrence rates, but whether it influences costs of treatment or downstream medical care is unknown. Methods: Using linked SEER-Medicare data from 1992–2005 for 5,905 women ages 66+ diagnosed with stage I breast cancer undergoing post-lumpectomy RT, we estimated mean total monthly costs paid by Medicare by phase of care (treatment, continuing, or terminal care). Continuing care covers costs after treatment including for recurrences, and terminal phase includes costs in the last 6 months of life. We evaluated whether costs were different by timely vs. delayed RT (delay = 12 weeks post-surgery, or 8 weeks post-chemotherapy) and patient characteristics including comorbidity, age, and race. Results: Mean monthly treatment costs were $427 lower for women with delayed RT (p < 0.00001), but monthly continuing-care costs were $129 higher (p < 0.00001). Delayed RT yielded a 26% decrease in monthly treatment cost...