Abstract P1-09-01: Impact of Granulocyte-Colony Stimulating Factor (G-CSF) Use on Medical Costs after Initial Chemotherapy in Early-Stage Breast Cancer (ESBC)

Abstract

Abstract Background: G-CSF minimizes severe neutropenia risk associated with chemotherapy, but its cost implications following chemotherapy are unknown. Objective: To examine the impact of G-CSF on medical costs after initial chemotherapy in ESBC (Stage I-III). Methods: Women diagnosed with ESBC in 1999-2005, who had an initial course of chemotherapy that began within 180 days of diagnosis and included ≥1 highly myelo-suppressive agent, were identified from the Surveillance, Epidemiology and End Results (SEER)-Medicare database. Medicare claims were used to describe the initial chemotherapy regimen according to the classes of agents used: anthracycline ([A]: doxorubicin or epirubicin); cyclophosphamide (C); taxane (T: paclitaxel or docetaxel); and fluorouracil (F). G-CSF use during initial chemotherapy was classified as follows: primary prophylaxis, if the first G-CSF claim was +/− 5 days of the start of the first chemotherapy cycle; secondary prophylaxis, if the first claim was +/− 5 days of the start of the second or subsequent cycles; G-CSF rescue, if the first claim occurred outside of prophylactic usage; and no G-CSF. Patients were described by age, race, year of diagnosis, stage, grade, ER/PR status, National Cancer Institute (NCI) Comorbidity Index, chemotherapy regimen, and type of G-CSF. Total direct medical costs from 4 weeks after the last chemotherapy administration up to 48 months were estimated. Medical costs included those for ESBC treatment and all other medical services received after chemotherapy. Least squares regression, using inverse probability weighting to account for censoring within the cohort, was used to evaluate associations between G-CSF use and costs, adjusted for patient demographic and clinical factors described above. Results: A total of 6,947 patients were identified with an average age of 72 years, of which 63% had Stage II disease, and 59% were ER and/or PR positive. Compared to no G-CSF, those receiving G-CSF primary prophylaxis were more likely to have Stage III disease (30% v. 16%), to be diagnosed in 2003-2005 (63% v. 26%), and to receive dose dense AC-T (25% versus 5%), while they were less likely to receive an F-based regimen (13% versus 34%). The estimated average direct medical cost over 48 months after initial chemotherapy was $81,045 in the cohort overall. In multivariate analysis, significantly greater costs were associated with stage II or III diagnosis (compared to Stage I), NCI Comorbidity Index score of 1 or ≥2 (compared to 0), or FAC or standard AC-T (each compared to AC). Adjusting for patient demographic and clinical factors, costs in the G-CSF primary and secondary prophylaxis groups were not significantly different from the no G-CSF group. In contrast, G-CSF rescue was associated with significantly greater costs (incremental cost = $9,930; 95% CI $2,234- $18,099) than no G-CSF. Conclusion: Direct medical costs after initial chemotherapy were similar between those receiving G-CSF primary or secondary prophylaxis and those receiving no G-CSF after adjusting for potential confounders. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-09-01.