OBJECTIVE: A retrospective claims analysis was performed examining costs of care for breast cancer patients. METHODS: Two years of claims data (1/94 to 12/95) were obtained from a provider of cancer care services to managed care organizations. Patients with a breast cancer-related medical claim (ICD-9 code of 174.X) were staged according to the following criteria: Stage I – lumpectomy, with no chemotherapy prior to or following lumpectomy, and no ICD-9 code of 196.X; Stage II – ICD-9 code of 196.3; Stage III – ICD-9 code of 196.X, but not 196.3; Stage IV – ICD-9 code of 197, 198, or 199. Costs, reflecting the amount reimbursed by the insurer, were calculated based on medical and pharmacy resource utilization. Average period costs were reported for each stage according to three timeframes: initial (6 months), maintenance (3 months), and terminal (6 months). RESULTS: A total of 1822 female patients had a breast cancer-related medical claim during this period; 530 patients were considered evaluable based upon available data. Stage I patients had the lowest overall costs ($9,572), while Stage IV patients experienced the highest overall costs ($34,448). Too few Stage III patients (n=19) were identified to draw conclusions. Overall, highest costs were observed during the terminal period. When data from all patients were analyzed, per-patient costs were $7,183 over an initial six-month period, $3,901 over a three-month maintenance period, and $12,080 over a six-month terminal period. CONCLUSIONS: These results indicate that breast cancer patients in this setting utilized substantial medical resources, particularly during the terminal phase of care, and that utilization, in general, increased with stage. Stage nInitial CostsMaintenance CostsTerminal CostsTotal Costs I228$4,169$1,992$3,411$9,572 II87$6,371$3,131$5,176$14,678 III19$637$557$7,905$9,099 IV196$12,159$5,602$16,687$34,448 All530$7,183$3,901$12,080$23,164