Abstract P4-01-11: Patient-reported outcomes assessment using mobile applications in the HR+/Her2- breast cancer adjuvant setting

Abstract Introduction: Adjuvant treatments for HR+/Her2- breast cancer include various options such as tamoxifen, aromatase inhibitors, CDK4/6 inhibitors, and ovarian suppression. These agents are associated with specific adverse events, which may impair quality of life and treatment adherence. Numerous studies have shown that adverse events are often underreported in clinical records. This study aimed to evaluate the adherence to online questionnaires for patient-reported outcomes (PROs) using a mobile application based on the Spanish version of the PRO-CTCAE tool. Methods: An online questionnaire was designed using 39 questions from the Spanish version of the PRO-CTCAE tool. Patients were instructed to complete the questionnaire after the first month of adjuvant treatment and then every six months, with email reminders. The questionnaire was available for completion at the patient's request. The primary objective was to evaluate adherence to online questionnaires, with the expectation that at least 73% of a sample size of 42 patients would answer two questionnaires after one year of follow-up. Secondary objectives included evaluating the incidence of self-reported adverse events across different treatment types. Fisher tests and longitudinal-analysis models using generalized estimating equations were performed to evaluate the incidence of adverse events throughout the patients' follow-up. A p-value of <0.05 was defined for statistical significance. This pilot experience only included patients from an Argentinean private center, Instituto Alexander Fleming. Results: Forty-two patients were included between December 2022 and June 2023, and a total of 123 questionnaires were recorded. The median age was 51.5 years (range 32-73), 59.5% were premenopausal, 14.3% received ovarian suppression, and 16.7% received abemaciclib. 95.2% of patients were followed up for more than one year. The median number of completed questionnaires was three (IQR 1-5). Additionally, 85.7% (95% CI: 71-97%) and 66.6% (95% CI: 50-80%) of the cohort answered one and two questionnaires, respectively. The most reported adverse events were decreased libido (81%), headache (78.6%), and insomnia (78.6%). Treatment with tamoxifen was associated with higher intensity of specific adverse events, including decreased libido (p=0.021) and insomnia (p=0.049). Higher intensity of diarrhea was more frequently reported among patients receiving abemaciclib (p=0.024). Longitudinal analysis showed that the incidence and intensity of hot flushes increased during the first year of follow-up (p=0.024). Conclusions: This study represents the first experience of PRO assessment using online and mobile applications in Argentina. Strategies tailored to our population are required to promote adherence to online questionnaires, which may include WhatsApp text messages and patient education materials. As expected, this study allowed the recognition of certain treatment-related adverse events that are often overlooked during medical visits. Citation Format: Federico Waisberg, Alexis Ostinelli, Sergio Rivero, Laura Lapuchesky, Diego Enrico, Alejandro Frydman, Andrés Rodriguez, Carlos Palmés, Claudio Paletta, Matías Chacón, Jorge Nadal, Victoria Costanzo, Adrián Nervo. Patient-reported outcomes assessment using mobile applications in the HR+/Her2- breast cancer adjuvant setting [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P4-01-11.