Real-world data analysis of perioperative chemotherapy patterns, G-CSF use, and FN status in patients with early breast cancer.

Purpose: This study aimed to describe perioperative chemotherapy patterns, granulocyte colony-stimulating factor (G-CSF) use, and febrile neutropenia (FN) status in patients with early breast cancer (EBC) using real-world data in Japan.

Methods: This retrospective observational study used anonymized claims data. The included patients were ≥ 18 years old, were female, and had breast cancer diagnosis and surgery records between January 2010 and April 2020. Measures included perioperative chemotherapy, G-CSF use (daily and primary prophylaxis [PP]), and FN and FN-related hospitalization (FNH), all examined annually. Perioperative chemotherapy was examined separately for human epidermal growth factor receptor 2-positive/negative (HER2±). A multivariate logistic regression was used to explore the factors associated with FNH.

Results: Of 32,597 patients, those with HER2 + EBC treated with anthracycline-based regimens followed by taxane + trastuzumab + pertuzumab increased since 2018, and those with HER2 - EBC treated with doxorubicin/epirubicin + cyclophosphamide followed by taxane and dose-dense regimens increased after 2014. The proportion of patients prescribed daily G-CSF declined after 2014, whereas that of pegfilgrastim PP increased. The incidence proportion of FN remained at approximately 24-31% from 2010 to 2020, while that of FNH declined from 14.5 to 4.0%. The odds of FNH were higher in those aged ≥ 65 years and lower with pegfilgrastim PP administration.

Conclusion: Despite the increasing use of escalated regimens in the last 5-6 years, FNH continuously declined, and the odds of FNH were lower among patients treated with pegfilgrastim PP. These results may suggest the contribution of PP in part to suppressing FNH levels over the last 5-6 years.