The study will be a cluster randomized controlled trial of mosques to evaluate the impact of the education intervention. Each mosque is a cluster and intervention will be administered on a cluster level. We constructed a sampling frame of 29 large residential mosques out of the 70 mosques in Singapore. We excluded non-residential mosques and small mosques as these mosques do not conduct religious classes. From this sampling frame, we selected all 12 mosques that fulfilled the following eligibility criteria: i) a distance of at least 3.0 km from each other, to reduce bias of contamination, ii) availability of a parking space or an open area nearby for the MammoBus, and iii) high proportion of female mosque attendees as indicated by the Islamic Religious Council of Singapore (MUIS) which oversees the mosques in Singapore. We invited 12 mosques and received agreement from 6 mosques (clusters) for this trial. We stratified the mosques into 3 major housing estate regions (i.e. west, central and north), for stratified block randomization. Two mosques within each block or region were randomized by an independent researcher who is not on the study team, to the intervention arm and control arm (allocation ratio 1:1) using the ralloc package of STATA statistical software. Allocation will not be concealed. Three mosques on the intervention arm will receive the intervention package on breast cancer screening and three mosques on the control arm will receive an intervention package on healthy lifestyle. A total of 660 women will be recruited for the study by the research team on mosque grounds. All data collection is estimated to complete in 8 months.

Participants in the intervention arm will have three research visits and one optional research visit, therefore four research visits in total. Participants in the control arm will have three research visits in total. In both arms, all research visits will be conducted on mosque grounds. Mosque officers will allot time at the start or end of religious classes attended by potential participants to the research team to explain on the research study. Interested participants may approach interviewer in the mosque to sign up for the study. During recruitment, interviewer will go through the Participant Information Sheet and obtain verbal Informed Consent before conducting a baseline questionnaire. Only participants from the intervention arm will be asked for consent to be re-contacted for recruitment for a future study, a focus group discussion as the future study is not applicable for the control arm. Participant will be able to choose to attend one of the two available education sessions that will be held in the mosque over the next two weeks. Participant will be given a participant card to help them keep track of the dates of the session. The education session will be the second research visit for both arms. The third research visit is a voluntary session for those in the intervention arm, where participants may take part in a mammogram screening session in the mosque. The final research visit for both arms, fourth and third for intervention and control arm respectively, will take place between 2 months (± 1 month is applicable) from the recruitment, where a post-intervention survey will be carried out in the mosque. During this final research visit, participants that consented to be re-contacted for recruitment of a future follow-up study will be invited to participate in the follow-up study which is a focus group discussion.

Intervention package - i) Breast Cancer Screening: Participant will be required to complete a baseline questionnaire (10-15 minutes) upon recruitment and consent. Following recruitment, participant will be required to attend a group-level education session on breast cancer screening in the Malay language. This education session will last for an hour: 25 minutes education session by religious leaders on health-promoting Islamic teachings specifically on punitive religious beliefs, 10 minutes video on positive screening experience and breast cancer journey by breast cancer survivors, and 25 minutes question and answer on breast cancer by Malay-speaking health care provider. Participants will be asked to complete a short feedback form on the session. Participant will be given an educational pamphlet to reinforce health messages from the session and will be invited to attend a mammogram screening on the MammoBus. Participant may approach interviewers to sign up for the mammogram or register through the QR Code available on the participant card. This mammogram screening is voluntary and will be carried out in a MammoBus that will be deployed to the mosque in the following 2 weeks. The mammogram service is outsourced to National Healthcare Group Diagnostics (NHGD), that manages the MammoBus. The research team will only be involved in organising the mammogram appointments. Mammogram screening is a standard procedure in Singapore. In this research, mammogram screening will be according to the standard procedures and will be conducted by the trained radiographers from NHGD. Including waiting time and registration, this session should last for approximately 1 hour. Cost of mammogram screening will be borne by participants, where applicable. NHGD will inform participants of the results via mail when available. The research team and NUS as a whole will not have access to the mammogram results of the participants. At follow-up, 2 months (± 1 month is applicable) from the recruitment, participant will be required to answer a post-intervention questionnaire (10-15 minutes) which will be similar as the baseline survey, to measure changes in perception.

ii) Healthy lifestyle: Participant will be required to complete a baseline survey (10-15 minutes) upon recruitment and consent. Next, the participant will attend a group-level education session on healthy lifestyle in the Malay language. This education session will last for an hour - 30 minutes education session by religious leaders on health-promoting Islamic teachings, and 30 minutes question and answer on healthy lifestyle by Malay-speaking health care provider. Participants will be asked to complete a short feedback form on the session. At follow-up, 2 months (± 1 month is applicable) from the recruitment, participant will be required to answer a post-intervention questionnaire (10-15 minutes) which will be similar as the baseline questionnaire, to measure changes in perception.

Questionnaire and data collection - All data collected through questionnaires (pre-intervention questionnaire, feedback form and post-intervention questionnaire) will be linked via a unique code which will be given to the participant at recruitment and only this code will be used on all data. A separate encrypted file containing personal data of participants (i.e. phone number, name) linked to their unique code will be available only to the study administrator who is managing the service operations (i.e.arranging follow-up sessions and sending text reminders) of the study. A separate encrypted file containing personal data of participants that choose to go for mammogram (i.e. name, NRIC, phone number, address and date of birth) will be available only to the study administrator who is managing the mammogram appointments. Upon completion of all follow-up, recruitment for the follow-up study or completion of the mammogram appointment, whichever later, the files will be deleted therefore irreversibly de-identifying the data.