The American Society of Clinical Oncology (ASCO) released an update to their clinical practice guideline on the use of white blood cell growth factors. This update replaces the previous version, published in July of 2015. The 2026 update features a dozen recommendations, which are keys to answering a selection of clinical questions including, “What factors should influence the decision to administer primary prophylaxis of febrile neutropenia with a CSF?” and, “Are there circumstances in which CSFs may be administered for the treatment of febrile neutropenia?” Additionally, Table 2 in the update features initiation, duration, dosing, and administration of CSFs recommendations on filgrastim, including biosimilars, pegfilgrastim, including biosimilars, eflapegrastim-xnst, and sargramostim.

With the seven key clinical questions highlighted below, we’re providing the paralleled recommendations of each to help you understand what’s new in the 2026 update. Refer to the full-text version of the guideline update for the most thorough explanation of these recommendations.

Key Clinical Questions and Recommendations from the 2026 Update

What factors should influence the decision to administer primary prophylaxis of febrile neutropenia with a CSF?

  • Recommendation: Patients should be offered primary prophylaxis with a G-CSF when the risk of febrile neutropenia, secondary to a chemotherapy regimen, is equal to or greater than approximately 20%, unless an alternative chemotherapy regimen with comparable efficacy and safety that does not require G-CSF is available.
  • Recommendation: Among patients who receive chemotherapy with a lower risk of febrile neutropenia, primary prophylaxis with a G-CSF should be offered if a patient is at high risk of complications from febrile neutropenia based on age, comorbidities, or disease characteristics, and no alternative chemotherapy regimen with comparable efficacy and safety that does not require G-CSF is available.
  • Recommendation: If G-CSF is not affordable or available, antibiotic prophylaxis may be offered. Qualifying statement: Antibiotic prophylaxis is not a preferred option due to the risk of antimicrobial resistance, disturbance of gut microbiome, Clostridioides difficile infection, and other adverse effects, which may outweigh the benefits of antibiotic use in many cases.

What factors should influence decisions regarding secondary prophylaxis of febrile neutropenia with a CSF?

  • Recommendation: Secondary prophylaxis with a CSF is recommended for patients who experienced a neutropenic complication from a previous cycle of chemotherapy (for which primary prophylaxis was not received), in which a reduced dose or treatment delay may compromise cure rates or survival outcomes. In many clinical situations, dose reduction or delay may be a reasonable alternative or additional strategy.

Are there circumstances in which CSFs may be administered for the treatment of febrile neutropenia?

  • Recommendation: A CSF should not be routinely used for patients with neutropenia who are afebrile.
  • Recommendation: A CSF should not be routinely used as adjunctive treatment with antibiotic therapy for patients with fever and neutropenia.
  • Recommendation: A CSF may be offered in patients with fever and neutropenia who are at high risk for infection-associated complications or who have prognostic factors that are predictive of poor clinical outcomes.

What is the role of CSFs as adjuncts to progenitor-cell transplantation?

  • Recommendation: A CSF should be used alone, after chemotherapy, or in combination with a CXCR4 inhibitor (plerixafor or motixafortide), to mobilize peripheral-blood progenitor cells. Choice of mobilization strategy depends in part on the type of cancer and type of transplantation.
  • Recommendation: A CSF should be administered after autologous SCT to reduce the duration of severe neutropenia.
  • Recommendation: A CSF may be administered after allogeneic SCT to reduce the duration of severe neutropenia.

Should CSFs be avoided in patients receiving concomitant chemotherapy and radiation therapy?

  • Recommendation: CSFs are not recommended in patients receiving concomitant chemotherapy and radiation therapy, particularly involving the mediastinum. Note: There is little evidence regarding use of CSFs in patients receiving radiation therapy alone.

Do CSFs differ in efficacy or safety?

  • Recommendation: Filgrastim, pegfilgrastim, eflapegrastim, and biosimilars can be used for prophylaxis or treatment of febrile neutropenia. The choice of agent depends on cost, patient convenience, availability, accessibility, health system context, disease subtype, and treatment regimen.

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