Acceptability of Sharing Internet Browsing History for Cancer Research: Think-Aloud and Interview Study.

Background: Growing interest surrounds how internet search behaviors might provide digital signals of disease prior to diagnosis, for example, when people search symptoms online. Internet browsing data offer novel opportunities for understanding response to symptoms, public health surveillance, and early intervention in conditions such as cancer. However, the acceptability of using such sensitive data in medical research remains unclear, particularly among individuals at higher risk of health and digital exclusion, such as older adults and those from minority ethnic groups or with a lower socioeconomic status. Objective: This study aims to explore the feasibility and acceptability of using internet browsing history data for health research. Methods: Participants were purposively sampled to ensure representation from groups at risk of digital and health inequalities via community organizations and charities. We conducted semistructured and think-aloud interviews allowing participants to reflect on hypothetical research involving sharing their internet browsing data. The adapted theoretical framework of acceptability guided the interview structure and coding. The interviews were transcribed, coded in NVivo, and thematically analyzed. Patient and public involvement informed the study approach, participant-facing documents, and the interpretation of the findings. Results: Twenty participants (10 with a history of cancer and 10 without) were included in the study representing a range of age, gender, and ethnic and socioeconomic groups. Key themes focused on factors necessary for acceptability, including trust, transparency, and control and on perceived feasibility and individual willingness. Trust and transparency were fundamental to participants' willingness to share data. Trust in researchers would have to be earned through clear communication, ethical data handling, and familiarity with a named research team. Privacy concerns were prominent, with participants wanting control over what was shared, particularly regarding nonhealth-related information (such as details related to banking) or activity related to others (such as their children). Potential use or misuse of data beyond the original research purpose caused more concern than the nature of the shared data itself. Digital literacy varied; many expressed concerns over the technical aspects of sharing data. Participants also doubted the value of their individual internet browsing history, for example, as they chose not to search for health information due to the prevalence of misinformation. However, they described wider benefits arising from internet browsing history research, such as potential advancements in early detection and opportunities to promote credible online sources. Conclusions: Participant recommendations balanced privacy concerns against the potential of internet history data for early diagnosis and health research. The study highlights ethical and inclusive approaches to health research using internet browsing history. Future researchers should consider defining the scope of health-specific data filters, providing user-friendly information and guidance for study participants, and ensuring that participants are able to contact research team members to build trust and facilitate data sharing.