Breast cancer (BC) is the fifth leading cause of cancer deaths in women worldwide. In Hong Kong (HK), BC is the most common cancer, ranking third in cancer deaths among females. International guidelines advocate regular mammographic screening for women aged 40-50 to 69-74, reducing BC mortality by 20%.

The success and effectiveness of an organized cancer screening program are largely dependent on high adherence or uptake rates. However, nonadherence to BC screening is common and the suboptimal uptake rate remains a challenge, particularly in Asian countries.

Conventional interventions are effective in increasing mammographic screening uptake but are time-consuming, labor-dependent, and expensive. Mobile messenger chatbots are a potential cost-saving tool for enhancing BC screening uptake because they involve only a one-off development cost and a small maintenance cost . Currently, most studies evaluating the effectiveness of mobile health interventions in improving mammography screening uptake have been conducted in Western populations . Health-seeking behaviors for cancer screening in the Chinese population differ from those of Caucasians because of differences in culture, health beliefs, and education, especially regarding breast-related diseases. Chinese women often feel embarrassed when talking with healthcare workers in person about breast health. Communicating with a fully automated chatbot can minimize embarrassment. Additionally, linguistically and culturally tailored interventions are effective in increasing cancer screening rates in the Chinese population.

However, studies evaluating combined theory-based mHealth interventions to enhance BC screening uptake are scarce. Two theory-based WhatsApp chatbots were developed to promote CRC screening, and the longitudinal repeat fecal immunochemical test (FIT) adherence rate of a population-based CRC screening program in HK. These two chatbots used in investigator's previous studies had designs similar to that of the proposed chatbot, except for the health education materials. The chatbot design can be adopted directly with minor modifications to the workflow, replacement of content from CRC screening-related to BC screening-related, and culturally modified education materials. Consequently, the investigators can develop a new chatbot for this study at a lower cost and in a shorter time.

In the past two decades, internet and mobile phone usage has increased due to affordability. The COVID-19 pandemic has further necessitated online and phone-based healthcare, paving the way for less labor-intensive, cost-effective mHealth interventions. These include short message service (SMS) text messages, telephone calls, email, social media, and mobile apps, which have significantly boosted BC screening uptake by 1.2%-50.9%. Among them, manual calls and SMS are prevalent methods. Manual calls facilitate interactions with subjects, aiding informed decision-making and participation but require high manpower. Although SMS offers automatic communication and chatbot features, each message costs approximately HKD$0.2, posing long-term economic challenges, especially for population-based interventions. Conversely, chatbots based on mobile messengers, like WhatsApp are less expensive due to unlimited free text and multimedia messaging across different mHealth operating systems. WhatsApp is globally prevalent, including in HK and has been successfully implemented in various clinical settings. Given these promising results, the investigators believe that mobile messenger-initiated chatbots have an extended role in the BC screening uptake rate because of the ubiquity, acceptability, and effectiveness of mHealth interventions. However, studies evaluating combined theory-based mHealth interventions to enhance BC screening uptake are scarce.

Inclusion Criteria:

1. asymptomatic Chinese Women
2. 44-69 years old
3. eligible to enroll in a government-subsidized risk-stratified BC screening program
4. ability to read Chinese

Exclusion Criteria:

1. moderate- or high-risk women as defined by the local risk-stratified BC screening program
2. inability to provide informed consent
3. incomplete conversation with the chatbot.

female

Still being decided

Participants will not know what arm they are randomized into.