The Perils and Consequences of Payer Step Editing ("Step Therapy") in U.S. Medical Oncology: Evidence, Case Examples,...

Step therapy ("fail-first") policies require patients to initiate treatment with a payer-preferred regimen, often selected for cost, before coverage is granted for the oncologist-recommended therapy. In medical oncology, where biologic heterogeneity, biomarker-directed therapy, and time-sensitive sequencing determine outcomes, step edits can function as an avoidable barrier to evidence-based care. We performed a narrative review of peer-reviewed literature (2010-2025) and relevant U.S. regulatory and policy documents to summarize the clinical, economic, and equity implications of step therapy as applied to systemic anticancer treatments. Evidence from cancer-specific and cross-cutting utilization management research suggests that coverage restrictions can delay initiation or continuation of therapy and increase treatment discontinuation. We synthesize mechanisms of harm (time-to-treatment delays, forced non-guideline-concordant sequencing, and toxicity exposure), describe contemporary case examples across therapeutic areas, and propose actionable policy remedies. Oncology-specific safeguards, including transparent clinical criteria, rapid exceptions and appeals, continuity-of-care protections, and provider performance-based exemptions ("gold-carding"), are essential to balance payer oversight with the imperatives of precision oncology.