Daily step count, patient- reported outcomes, and recurrence-free survival in early breast cancer survivors

The National Cancer Institute awarded Dana-Farber Cancer Institute, Inc. $168,960 on September 3, 2026, under the Cancer Research Manpower program (CFDA 93.398) to investigate the relationship between daily step count trajectories measured by wearable devices and patient-reported outcomes and recurrence-free survival in early breast cancer survivors.

The research uses longitudinal data from wrist-worn actigraph devices deployed in the Breast Cancer Weight Loss (BWEL) trial, an NCI-funded phase III randomized trial of 3,180 women with stage II-III breast cancer and BMI ≥ 27 kg/m² testing the impact of supervised weight loss intervention on invasive disease-free survival. The study addresses a gap in evidence: prior research on physical activity and breast cancer outcomes relied on self-reported measures at single time points or small-scale controlled trials, whereas real-world wearable monitoring enables continuous collection of detailed longitudinal activity data. Step count serves as both a patient-facing goal-setting metric and a clinician-facing monitoring tool accessible to cancer survivors.

Performance occurs in Boston, Massachusetts, with a completion date of August 31, 2028. The award is obligated at $168,960.

Abstract

Breast cancer is the most common noncutaneous cancer and the second leading cause of cancer death among US women, with an estimated 316,950 new cases and 42,170 deaths in 2025. Obesity and physical inactivity are poor prognostic factors in early breast cancer. Adopting a physically active lifestyle shows promise in improving disease and patient-reported outcomes due to its favorable effects on body composition, as well as metabolic, inflammatory, and immune pathways. However, evidence linking physical activity with health outcomes in early breast cancer has primarily been generated from studies using self-reported measures of physical activity at a single time point or from small-scale clinical trials in highly controlled settings, which may not demonstrate real-world effectiveness. Advancements in wearable devices have facilitated the continuous monitoring of activity trajectories in large-scale studies to collect more detailed and precise longitudinal data. Wearable devices measure movements or accelerations of the human body in real time, which can be translated into understandable, behavior-oriented metrics. Step count is one of the most accessible and widely used metrics for monitoring physical activity levels, serving both as a tool for goal setting from the patient's perspective and as a method of monitoring from the clinician's perspective. Yet, no study has investigated the relationship between daily step count trajectories after a cancer diagnosis and patient-reported outcomes or survival among early breast cancer survivors. The breast cancer weight loss (bwel) trial is an NCI-funded phase III randomized trial in the US testing the impact of a supervised weight loss intervention (WLI) on invasive disease-free survival (idfs) in 3180 women with stage II-III breast cancer and a BMI ≥27 KG/M2. Wrist-worn actigraph devices were used to measure objective physical activity in a subset of 540 WLI and control participants at baseline and at 6, 24 and 36 months. All WLI participants received a fitbit tracker as a motivational device. After beginning my postdoc training, i was able to derive step count data from the fitbit and actigraph, enabling me to track activity metrics over time in bwel participants. The goal of this K99/R00 proposal is to develop, validate and apply daily step count metrics from fitbit and actigraph (aim 1) and evaluate the longitudinal relationship of daily step count metrics with patient-reported outcomes (aim 2) and recurrence-free survival in early breast cancer survivors (aim 3). Through coursework and mentorship, i will develop expertise in cancer survivorship, digital health, epidemiologic and biostatistics methods, and primary data collection in oncology settings. Building on my training in oncology population sciences, i aim to establish an independent research program in digital healthy living for cancer control, focusing on real-world evidence and leveraging wearable devices to deliver targeted behavorial interventions for diverse cancer survivors.