Background: According to clinical practice guidelines, the threshold for routine myeloid growth factor (MGF) PP is a high risk (>20%) of developing FN. However, in response to the COVID-19 pandemic, a recent recommendation expands this threshold for using MGF PP to include patients at intermediate risk (10-20%) of developing FN, with the goal of reducing emergency room and hospital visits. Patients with breast cancer receiving potentially curative chemotherapy consisting of docetaxel or paclitaxel (every 21 days) are at an intermediate risk (10-20%) of developing FN. This study evaluates the cost-effectiveness of PP vs. SP using a biosimilar MGF, filgrastim-sndz, in early-stage breast cancer patients at intermediate risk of FN. Methods: A Markov model with a lifetime horizon was constructed to evaluate the total costs and clinical outcomes when using filgrastim-sndz as PP vs. SP in 56 year old early-stage breast cancer patients receiving adjuvant docetaxel (following doxorubicin/cyclophosphamide) every 3 weeks for 4 cycles. Patients had ≥1 FN risk factor (i.e., recent surgery) without the receipt of anti-HER2 therapy, representing a 16% baseline FN risk. Average Sales Price (ASP) calculated from the Centers for Medicare & Medicaid Services July 2020 ASP Drug Pricing File was used as the filgrastim-sndz cost. Incremental cost-effectiveness ratios (ICERs) were calculated for cost per FN event avoided, life-year saved (LYS), and quality-adjusted life-year (QALY) gained from a United States payer perspective. Deterministic and probabilistic sensitivity analyses (PSA) were conducted. Results: Filgrastim-sndz as PP vs. SP provided an additional 0.102 FN events avoided, 0.065 LYS, and 0.056 QALYs at an incremental cost of $2,106. The ICERs were $20,656, $32,624 and $37,333 for cost per FN event avoided, cost per LYS, and cost per QALY gained, respectively. In the PSA, the likelihood of cost-effectiveness at a willingness-to-pay (WTP) threshold of $50,000 per QALY gained was 71.3%. Conclusions: For early-stage breast cancer patients at intermediate risk of FN receiving adjuvant docetaxel with 1 or more risk factors, PP with filgrastim-sndz compared to SP is cost-effective based on a WTP threshold of $50,000/QALY.