BACKGROUND: In oncology, especially with accelerated regulatory approvals and niche populations, US payers appreciate all evidence that can help support formulary decision making, including evidence beyond traditional safety and efficacy data from clinical trials. Research suggests payers incorporate patient-reported outcome (PRO) evidence in their decision making and expect the importance of PRO evidence to grow. Greater understanding on payers' use of PRO information in oncology is needed. OBJECTIVE: To assess US payer perceptions regarding the use of PRO evidence in informing oncology formulary decision making. METHODS: A multidisciplinary steering committee involving a measurement specialist, health economics and outcomes research experts, and payers developed a survey containing single-answer, multiple-answer, and free-response questions. The pilot survey was tested at a mini-advisory board with 5 US payers and revised based on feedback. In February 2020, the survey was distributed to 221 US payers through the AMCP Market Insights program and 10 additional payer panelists who were invited to discuss and contextualize the survey results. Results were presented primarily as frequencies of responses and evaluated by plan size, type of health plan, and geography (regional vs national). Differences in categorical data responses were compared using Pearson chi-square or Fisher exact tests. Two-tailed values are reported and a P value less than or equal to 0.05 was used to indicate statistical significance. RESULTS: Overall, 106 of 231 payers (45.9%) completed the survey; 45.5% represented small plans (< 1 million lives), and 54.5% represented large plans (≥ 1 million lives). Respondents were largely pharmacists (89.9%), with 55.6% of all respondents indicating their job was pharmacy administrator. The majority of payers (60.0% of small health plans and 57.8% of large plans) felt PRO evidence from clinical trials is useful. Similarly, the majority of payers (57.8% of small plans and 51.9% of large plans) felt PRO evidence from real-world studies is useful. Almost half (47.1%) suggested formulary review would be influenced by a lack of PRO evidence from oncology clinical trials either somewhat, much, or a great deal. Most payers (78.2%) thought PRO evidence is useful for providing additional context for safety of oncology therapies. More than one-third of payers (34.3%) valued PRO evidence when comparing 2 similar therapies, and 51.5% felt PRO evidence may help in measuring value for value-based agreements. Panelists indicated PRO evidence can be useful for developing treatment pathways for addressing health-related quality of life, informing provider-patient dialogues, and defining progression-free survival length and quality. CONCLUSIONS: US payers view PRO evidence from both clinical trials and real-world studies as useful for supplementing traditional clinical trial data when making oncology formulary decisions and for refining treatment pathways and care delivery models. Manufacturers of oncology therapies should collect and consider leveraging PRO evidence from both settings when engaging with US payers. DISCLOSURES: Pfizer provided funding for this research, and employees of Pfizer contributed to the development of the survey instrument, were involved in the interpretation of the data, and contributed to the discussion and output as authors. Biskupiak, Oderda, and Brixner are managers of Millcreek Outcomes Group and were paid as consultants on this project. Burgoyne was a consultant for Pfizer on this project. Arondekar, Deal, and Niyazov are employees of Pfizer and own Pfizer stock. Qwek was an employee of Pfizer at the time of this project and owns Pfizer stock.