Guidelines from the American Society of Clinical Oncology (ASCO) are an important resource for practicing oncologists. In February 2026, Bishal Gyawali, MD, PhD, FASCO, and colleagues provided updated guidance on the use of colony-stimulating factors (CSFs) for patients with cancer who are receiving systemic therapies. These guidelines provide insights into risk assessment for febrile neutropenia and exact cutoff criteria for prophylactic CSF use.
The updated guidelines specify criteria for both primary (use immediately when chemotherapy is initiated) and secondary (after chemotherapy has been initiated but is not complete) initiation of granulocyte (G)-CSF prophylaxis. Primary G-CSF prophylaxis is recommended when chemotherapy carries ≥20% febrile neutropenia risk, unless equally effective regimens not requiring CSFs are available. For regimens with <20% risk, primary prophylaxis should be considered for high-risk patients on the basis of individual factors. For this latter category, high-risk features warranting prophylaxis include age ≥65 years, frailty, advanced disease, previous chemotherapy/radiation, preexisting neutropenia or bone marrow involvement, active infection, poor performance status, low body mass index, renal/hepatic dysfunction, cardiovascular disease, and presence of multiple comorbidities. Thereafter, secondary prophylaxis (up-front use in subsequent therapy cycles) is recommended for patients who have experienced neutropenic complications in prior therapy cycles without prophylaxis when maintaining dose intensity would impact survival or cure rates. While secondary prophylaxis reduces neutropenic events and maintains dose intensity, current evidence does not demonstrate improved disease-free or overall survival.
The guidelines are clear that CSFs should not be used routinely in afebrile neutropenia, adjunctive treatment with antibiotics for febrile neutropenia, or for concomitant chemotherapy and radiation therapy, particularly mediastinal radiation.
For patients who need pheresis for autologous stem cell transplant or chimeric antigen receptor T-cell generation, CSFs may be used alone, post-chemotherapy, or combined with CXCR4 inhibitors (plerixafor or motixafortide) for peripheral blood progenitor cell mobilization.
The guidelines acknowledge new long-acting CSFs including eflapegrastim and efbemalenograstim alfa, alongside established filgrastim, pegfilgrastim, and their biosimilars. Agent selection will likely balance cost, patient convenience, availability, and health system context rather than efficacy differences.
This update reinforces risk-stratified CSF use while incorporating new biosimilar options, emphasizing individualized decision-making that balances efficacy, safety, convenience, and cost-effectiveness in standard clinical practice.
High Level
The updated ASCO Guidelines can be implemented into care pathways and considered for application in clinical trial protocols for oncology therapy development. This resource could serve as an important educational tool in training clinical staff in chemotherapy-administration centers.
Ground Level
These updates from ASCO provide important granularity on when utilization of prophylactic CSFs is appropriate in patients undergoing cancer treatments. However, every situation is unique, and clinical judgment will be needed to determine whether additional patients might benefit from prophylactic CSFs during treatment, such as those in whom neutropenic fever might go unnoticed. Moreover, the guidelines do not specifically recommend one CSF over another, but leave that decision dependent upon the associated circumstances (eg, cost, patient convenience, availability, and health system context).
