Abstract
Background: Population-based studies using patient-reported outcomes provide important insights into health-related quality of life (HRQoL) and the long-term impact of cancer and its treatment. Declining response rates and potential non-response bias have presented methodological challenges, particularly in registry-based surveys including both cancer survivors and population controls. The SURV-ICE study was established to assess HRQoL and health literacy among cancer survivors in Iceland while evaluating recruitment processes and participation patterns in a nationwide mixed-mode survey. Methods: SURV-ICE is a nationwide, population-based cross-sectional survey conducted in Iceland in 2025. Adults diagnosed with invasive cancer between 2014 and 2024 were identified through the Icelandic Cancer Registry and invited alongside an age- and gender-matched control group sampled from national registers. Participants completed validated EORTC instruments. Recruitment used a mixed-mode strategy including postal invitations, web-based and paper questionnaires, electronic reminders via the national health portal, and targeted telephone follow-up. Results: Among 10,005 cancer survivors 5489 (54.9%) responded to the questionnaires and among 5663 controls 2297 (40.6%) responded to the questionnaires. In both groups participation peaked among individuals aged 60-79 years and was lowest among the youngest and oldest groups. Cancer survivors had higher odds of participation than controls (OR 1.84; 95% CI 1.72-1.97). Most responses followed the initial postal invitation and first electronic reminder. Data completeness was high (≥80% item completion in 95.7% of instruments). Conclusions: Nationwide registry-based recruitment for large-scale PRO research is feasible in Iceland and can achieve competitive response rates without incentives. SURV-ICE provides an infrastructure for future research on cancer survivorship, HRQoL, and health literacy.