This registration covers only Aim 1b, which focuses on testing usability. The study will include 20 participants who are breast cancer patients. Participants will be observed using the tool on their mobile devices, and their experience will be evaluated using a "think-aloud" method to capture their thoughts and reactions. Interviews will include open-ended questions about the content and format of the decision aid, with follow-up prompts to gather feedback on design elements (length, order, graphics), comprehension, ease of use, acceptance, and engagement with the tool. Knowledge will be measured using the Decision Quality Instrument before and after using the tool. Results will be analyzed to develop recommendations for the final version of the tool.

This study is part of a larger project that will update and adapt an existing online decision tool called BREASTChoice. The project includes interviews and user testing with breast cancer survivors, interviews with medical experts, and updates to the website design.

Breast reconstruction after a mastectomy is an important part of breast cancer treatment. It can help restore quality of life and body image, which are often affected after surgery. However, many patients, especially those who identify as Black or Hispanic/Latina are not always offered reconstruction. Some patients also lack information about the risks and benefits, leading to choices that may not match their personal preferences.

The BREASTChoice decision aid was created to help patients make informed choices about breast reconstruction. It has been tested in two clinical studies and shown to improve decision quality. Patients and doctors found it helpful and easy to use, but many asked for a version that works better on mobile devices and can be shared with family and friends.

So far, BREASTChoice has mostly been used in clinics and has not reached many people outside of them. To reach more patients, the tool will be adapted for use on social media and online communities, places where many people already go for health information and support.

In the U.S., most adults use social media (about 81%) and search the internet for health information (about 72%). Even most older adults (60%) go online. Breast cancer survivors are especially active in online groups. Early findings show that survivors would use BREASTChoice if it were available through social media.

Following the Designing for Dissemination approach, and in partnership with three cancer survivor organizations and two clinician groups, this project will adapt BREASTChoice and share it through social media and online communities.

Inclusions Criteria To participate in this study, a subject must meet all the eligibility criteria outlined below.

• Age ≥ 18 years at the time of consent
• Able to read and speak English.
• Have had surgery, such as a mastectomy or lumpectomy, to remove some or all of their breast or breasts.
• Breast surgery occurred within the past 8 years.
• Breast surgery was due to a diagnosis of breast cancer, ductal carcinoma in situ, or risk of future breast cancer, by participant report.
• Sex was assigned "Female" at birth

Exclusion Criteria

• Individuals with self-reported or observed unstable medical or psychiatric conditions precluding informed consent or participation in the study will be excluded.