ImportanceCounseling prior to thyroid cancer (TC) treatment is an essential component of informed consent. An informed patient affects treatment-related expectations and patient engagement, factors that contribute significantly to patient-reported quality-of-life outcomes.ObjectiveTo describe experiences with pretreatment counseling among survivors of TC and to test factors associated with self-reported treatment meeting expectations.Design, Setting, and ParticipantsA cross-sectional survey was administered between October 18, 2019, and February 8, 2020, to members of ThyCa: Thyroid Cancer Survivors’ Association Inc, and to individuals accessing the public-facing ThyCa website. Survey respondents were asked 55 questions, including 4 free-text questions and 2 multiple-choice questions about pretreatment counseling.Main Outcomes and MeasuresRespondents self-reported (1) their unmet information needs, (2) rates of treatment meeting expectations, and (3) rates of treatment understanding. A mixed-methods analysis was performed, including qualitative content analysis of free-text responses and multivariable logistic regression of factors associated with self-reported levels of treatment meeting expectations.ResultsOf the 1412 survey respondents, 1249 were women (88.4%). The median age at diagnosis was 48 years (range, 18-85 years), and the median age at the time of survey completion was 60 years (range, 18-87 years). A total of 1259 respondents (89.2%) provided free-text responses to the question, “What would you tell someone newly diagnosed with your same condition?” Of these individuals, 526 (37.2%) reported inadequate pretreatment plan understanding and 578 (40.9%) reported that their treatment experience did not meet their expectations. Treatment met expectations for only 95 respondents (18.1%) reporting an inadequate pretreatment plan understanding. Of the 526 survivors of TC reporting a lack of understanding, 473 (90.0%) provided additional textual comments, most commonly in the categories of postoperative treatment, surveillance, and treatment effects. On multivariable logistic regression, self-reported failure to have an understanding of TC treatment was independently associated with failure of treatment to meet expectations (odds ratio, 5.1 [95% CI, 3.7-6.9]). Patients reporting a full understanding of their treatment plan were 5-fold more likely to indicate that their initial treatment experience was on par with expectations, independent of reported postoperative complications, age, sex, and other potential confounders.Conclusions and RelevanceIn this survey study, a substantial proportion of survivors of TC reported inadequate pretreatment understanding. This gap in understanding was associated with high levels of self-reported failure of treatment to meet expectations, which in turn is associated in other studies with poorer patient-reported quality-of-life outcomes. These outcomes may be improved by addressing gaps in patient understanding so expectations more closely match TC diagnosis and treatment pathways.