Background: In this era of smartphones, more and more people use mobile apps to help them with daily tasks. While this trend is penetrating the health industry, the mobile apps available are mostly fitness-related or health service provider-centric. Apps to help patients manage their conditions and health records are rare. Objective: The purpose of this study was to design a mobile app to help cancer patients manage their stressful daily routine and health records during their cancer journey. The study also investigated ways blockchain technologies can be deployed to ensure data on the app can be stored securely and that ownership of data belongs to the patient. Methods and Results: A survey and interviews were conducted, and a working prototype was developed based on the features requested by patients and carers. Conclusion: In this article, a patient-centric app for people dealing with cancer is presented. It was developed as a prototype following pilot research investigating patients' needs and requirements during their cancer journeys. This research paper also analyses the use of blockchain technologies to empower patients to own their health data. Finally, as this is research in progress, we discuss how this study will be advanced and the future work planned.