Abstract: Increasing incidences of cancer have resulted in a heavy disease burden for the whole country and society, early cancer screening is one of the critical bottlenecks for achieving early diagnosis and treatment of cancer. Traditionally, health education-based cancer screening interventions do not take into account the irrationality in people's decision-making on cancer screening, and as a result, the participation rates in early cancer screening in pretty low. Advances in the behavioral sciences provide insights to nudge cancer screening. Depending on whether the nudge strategy involves reflective thinking and who is being nudged, cancer screening nudging strategies can be categorized into interventions that nudge recipients and providers through System 1 and interventions that nudge recipients and providers through System 2. This categorization not only provides a more comprehensive framework for various cancer screening intervention strategies, but also allows for quick selection of intervention strategies for different recipients. In addition, the framework can also inform the further development and validation of behavioral intervention strategies for nudging cancer screening.
The first type of intervention strategy is nudging cancer screening recipients through System 1 thinking. Focusing primarily on the automatic thinking of recipients, this type of strategy promotes people to uptake cancer screening by activating their instinctive and automated responses or habits. These strategies include setting participation in cancer screening as the default option, increasing screening rates through inducing future-oriented emotional responses, sending notifications in advance or motivating people to participate in cancer screening through choice architecture design (e.g., highlighting the scarcity of screening services, inducing psychological ownership, and the decoy effect).
The second type of intervention strategy is one that nudge cancer screening providers through System 1 thinking. Utilizing providers' automatic thinking, this type of strategy sets default reminders for providers to prescribe cancer screening services through electronic health records whenever patients are eligible, which can effectively address the problem of physicians forgetting to schedule cancer screening appointments for their patients, helping to increase screening appointment rates and, in turn, increasing patients’ participation in screening.
The third type of intervention strategy is one that nudge cancer screening recipients through System 2 thinking. Triggering people's reflective thinking, this type of strategy promotes people to actively think about the benefits of early cancer screening and make their own judgments and choices. These strategies include the use of social norms, framing of screening messages, emphasizing the ethical and social responsibility of early cancer screening, or setting up an active choice architecture for screening participation that triggers the public to think about the pros and cons of screening, as well as using pre-commitment devices to encourage the public to delineate their implementation intentions for early cancer screening, and thereby increase completion rates for early cancer screening.
The last type of intervention strategy is one that nudge cancer screening providers through System 2 thinking. This type of intervention strategy can be achieved by constructing active choice architectures that prompt physicians to reflect on the pros and cons of scheduling cancer screening appointments for their patients, thereby increasing cancer screening appointment rates, or by evaluating and providing feedback on a physician's performance in providing early cancer screening, prompting them to think about their own performance, or even to compare their performances with their colleagues, to further increase the prescription of early cancer screening services for eligible patients, thus improving patients’ participation in early cancer screening.
Complementary to traditional cancer screening strategies such as promoting early cancer screening through providing health education and financial incentives, behavioral science-based cancer screening nudging strategies focus on addressing the irrational factors that preclude people from participation early cancer screening. These nudge strategies are typically low-cost, easy to implement, and scalable. Future studies are needed to explore the effectiveness and mechanisms of nudging interventions to promote early cancer screening. This line of research will have implications for developing culturally appropriate, integrated, digital, precise, and intelligent early cancer screening interventions, and contribute to achieving the goal of cancer prevention and control initiative of the Healthy China Action (2019~2030) plan.

Key words: cancer screening, cancer prevention, nudge, behavioral intervention, behavioral public health