TOPLINE

Women with breast cancer receiving chemotherapy and primary prophylactic colony-stimulating factor (PP-CSF) experienced low rates of febrile neutropenia (FN) regardless of delivery method — in-clinic administration (IC), on-body device (OBD), or self-injection (SI). FN occurred in 3.8% of patients receiving IC, 5.0% receiving OBD, and 6.4% receiving SI, with no statistically significant differences between groups. High-risk chemotherapy regimens and worse performance status were associated with increased FN risk, whereas delivery method and PP-CSF agent were not.

METHODOLOGY

• This secondary analysis of the SWOG S1415CD trial, a pragmatic cluster-randomized study, evaluated associations between PP-CSF delivery method and FN among female patients with breast cancer receiving first-line chemotherapy.
• A total of 1713 women were included, with a median age of 55 years (IQR, 46-64); 773 (45%) received IC administration, 862 (50%) received OBD, and 78 (5%) received SI.
• By disease stage, 566 (33%) had local disease, 709 (41%) regional, 41 (2%) distant, and 397 (23%) unknown stage; most patients (87%) received high-risk FN chemotherapy regimens.
• The primary outcome was FN within 6 months of chemotherapy initiation, defined per the Common Terminology Criteria for Adverse Events as absolute neutrophil count <1000 cells/mL and temperature >38.3 °C or sustained temperature ≥38 °C for more than 1 hour.
• Pegfilgrastim was used in 98% of IC patients, 99% of OBD patients, and 29% of SI patients; the remainder of SI patients received filgrastim or tbo-filgrastim.

TAKEAWAY

• FN incidence at 6 months was 3.8% (95% CI, 2.5 to 5.3) in the IC group, 5.0% (95% CI, 3.6 to 6.6) in the OBD group, and 6.4% (95% CI, 2.1 to 14.3) in the SI group (P = .29).
• In multivariable logistic regression, high-risk FN chemotherapy regimens were associated with increased odds of FN (odds ratio [OR], 2.97; P = .04).
• Zubrod performance status ≥2 was significantly associated with FN (OR, 4.99; P = .01), whereas performance status 1 did not reach statistical significance.
• Neither PP-CSF delivery method nor PP-CSF formulation (filgrastim vs pegfilgrastim) was significantly associated with FN risk in an adjusted analysis.

IN PRACTICE

"These findings support selecting the PP-CSF delivery method based on patient preference, access, insurance coverage, and care delivery logistics without significant differences in FN risk," wrote the authors of the study.

SOURCE

The study was led by Lauren Shih, MD, University of Washington in Seattle. It was published online on October 6 in JCO Oncology Practice.

LIMITATIONS

The analysis was restricted to female patients with breast cancer, limiting generalizability to other cancer types. The small sample of SI users and overall low FN incidence constrained the ability to detect modest differences between delivery methods or to draw definitive conclusions about SI administration. Patient-reported outcomes regarding preferences, experiences, and adherence to PP-CSF were not collected.

DISCLOSURES

The study was supported by grants from the National Cancer Institute and a Patient-Centered Outcomes Research Institute award. One author reported receiving grants and fees from Bayer HealthCare Pharmaceuticals, Corbus Pharmaceuticals, and Bristol Myers Squibb. Another author is employed by Curta Consulting. One author reported receiving research funding from Merck, and another reported a consulting role with AIM Specialty Health. Additional author disclosures are reported in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.