Background Gastric cancer is one of the most common gastrointestinal cancers. Patients with gastric cancer experience disabilities and complications that lead to reduced quality of life. Empowering these patients by providing them with information and self-management skills can help reduce side effects and improve their quality of life. Objective The aim of this study was to identify the user requirements for developing a mobile-based self-management app to support patients with gastric cancer. Methods Data were analyzed using descriptive statistics and frequency distribution reports using IBM SPSS Statistics software. Results All of the data elements and functional requirements except “data recording times” and “weight changes in graphs” were identified as essential by clinical experts and patients. Among the functional requirements required in a gastric cancer self-management app, the capabilities related to informing, announcing warnings, and reminders are included. In the demographic data section, most patients (14/26, 53%) did not comment on the importance of recording data such as name, surname, and place of residence, and the demographic data section was met with less agreement from patients than clinicians. Conclusions Applying the requirements mentioned in this study can improve the self-management of patients with gastric cancer. Such apps can play an important role in empowering patients and improving their quality of life. However, the apps need to be designed and implemented to see how they can meet users’ requirements.

BACKGROUND Gastric cancer is one of the most common gastrointestinal cancers that has a global prevalence and is one of the most common types of cancer in Iran. Patients with gastric cancer experience disabilities and complications that lead to reduced quality of life. To reduce symptoms and complications, costs, and increase the quality of life, patients should increase their awareness of the disease to control and manage it. OBJECTIVE Objective: Because the use of mobile-based technologies today plays a helpful role in the quality of life of patients with gastric cancer, the aim of this study was to identify the requirements of mobile-based applications for the supporting these patients. METHODS Methods: This research was applied research conducted in 1399-1400. This research was a descriptive study and the relevant information was collected through a researcher-made questionnaire whose validity and reliability was evaluated. Participants in this study were two groups of patients and clinical experts. This research was conducted in two rounds of Delphi. Data were analyzed using descriptive statistics and frequency distribution reports using SPSS software. RESULTS Results: All of the data elements and most of the functional requirements except “the ability to display data recording hours” and “display weight changes in graphs” were found important by clinical experts and patients. The data elements were related to personal data, patient clinical data, disease management, and educational information. Among the functional requirements required in gastric cancer, self-management application can be mentioned to the capabilities related to informing, announcing warnings, and reminders of the program as well as display capabilities. In the demographic data section, most patients did not comment on the importance of recording data such as "name, surname, and place of residence" and were met with less agreement from patients than from clinicians. CONCLUSIONS Conclusion: Applying the requirements mentioned in the present study can improve the self-management of patients with gastric cancer. This application can play an important role in improving the quality of life of patients. However, the applications need to be designed and implemented to see how they can meet users’ requirements.