Abstract Background: Breast cancer is the most diagnosed cancer in women and a leading cause of cancer-related morbidity. Active treatments, such as chemotherapy, radiation, and targeted therapies, are frequently associated with fatigue, reduced physical activity, and decreased quality of life. Wearable activity trackers, including fitness bands and smartwatches, are increasingly being integrated into oncology care to track physical activity, monitor symptoms, and enhance patient engagement. Their use during active treatment provides new opportunities for behavioral support and real-time, remote monitoring. This study systematically examines the use of wearable activity trackers during active breast cancer treatment to monitor activity, track symptoms, support adherence, and enhance patient engagement. MethodsA comprehensive search using relevant keywords and MeSH terms related to ‘breast cancer’, ‘breast cancer treatment’, and ‘activity trackers’ was conducted until March 2025 across PubMed/Medline, Scopus and Web of Science. Studies that used wearable activity trackers in adult breast cancer patients receiving active treatment as part of clinical care or research were included. Data were systematically extracted on how activity trackers were used during active treatment and their intended purposes. The findings were synthesized narratively. Results: The final analysis comprised 40 studies involving over 8,000 participants. The included studies comprised of observational studies (prospective, longitudinal, and cohort) (n=25), randomized controlled trials (n=9), cross-sectional studies (n=4), and non-randomized interventional studies (n=3). Most studies (n = 18) were conducted in the United States. The most common wearable tracker was FitBit. Wearables were primarily used to track physical activity, assess symptoms such as fatigue and sleep issues, and enhance patient engagement and treatment adherence. 23 studies (57.5%) assessed physical activity, 18 (45%) studies assessed sleep, 10 (25%) studies evaluated fatigue, and 9 studies (22.5%) examined quality of life. 21 studies described adherence outcomes, with adherence rates ranging from roughly 16.9% to 96%, while 23 studies (57.5%) reported feasibility outcomes. The duration of time using wearables varied across studies. Conclusion: This study demonstrated that wearable activity trackers are practical and can be effectively utilized during active breast cancer treatment to monitor physical activity, sleep, and fatigue, while also supporting patient engagement and adherence. Most studies demonstrated high feasibility and acceptable adherence rates, underscoring the potential of these devices to enhance supportive care. With technological advancements, wearable trackers offer the potential for real-time detection of treatment-related toxicities and delivery of personalized interventions. Future research is needed to validate wearable-derived metrics and support their integration into clinical decision-making pathways, thereby optimizing outcomes in breast cancer care. Other future directions include leveraging wearables for tracking lymphedema, monitoring long-term cardiac health following anthracycline exposure, and evaluating toxicity profiles associated with the rise of HER2-targeted antibody-drug conjugates. However, key challenges remain, including data overload, limited integration with electronic medical records, and persistent issues of equity and access. Collaborating with companies to incorporate wearable data collection in clinical trials may help address these barriers, while efforts to ensure rigorous validation and standardization of wearable technologies will be critical to their successful adoption in routine oncology care. Citation Format: J. Hundal, S. Peshin, F. Bashir, H. Bazroodi, E. Takrori, M. Kurian. Use of Wearable Activity Trackers During Active Breast Cancer Treatment: A Systematic Review abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS1-04-26.
Hundal et al. (Tue,) studied this question.