JMIR Publications

ABSTRACT

Background:

Survivors of childhood cancer have an increased risk of cardiovascular disease (CVD), but that risk may be reduced by following healthy lifestyle behaviors.

Objective:

Using a sequential multiple assignment randomized trial (SMART) design, we sought to test different approaches to improve physical activity (PA) and diet quality among long-term survivors at increased risk of CVD over a 12-month period. The primary study outcomes are sedentary time and Healthy Eating Index (HEI) scores.

Methods:

Participants were recruited from the Childhood Cancer Survivor Study cohort, with eligibility defined as current age 18-54 years, and at least one of three self-reported criteria: 1) <30 minutes/day of moderate to vigorous PA; 2) HEI-2015 score <60; or 3) BMI ≥25 kg/m2. Eligible participants completed baseline surveys including a food frequency questionnaire and had PA measured by research-grade accelerometry, and were then randomized to one of three conditions: 1) control; 2) clinician-guided action plan [every 2-month sessions with study provider]; 3) mHealth-supported goal-setting [weekly PA and monthly diet goals based on PA and diet tracker feedback]. Following SMART principles, after 3-months, all participants’ PA levels and HEI scores were reassessed; participants from the two intervention groups who did not achieve ≥20-minute/day reduction in sedentary time or a ≥4-point increase in HEI score were classified as non-responders and re-randomized to the alternative intervention or a more intensive lifestyle coaching intervention (weekly sessions with study health coach). Intervention participants then entered a less intensive maintenance phase from months 7-12. All participants’ PA levels and HEI scores were reassessed at 12 months. Goal accrual was 375 with 95 controls and 140 in each of the initial intervention groups, which will allow the study to detect changes of 0.35 SD (~30 minutes/day) in sedentary time and 0.41 SD (~4 points) in HEI score between the control and intervention groups (combined). Secondary analyses will test whether there are differences in efficacy across the different intervention strategies, and which intervention sequences are associated with the greatest reduction in sedentary time and improvements in diet quality.

Results:

From April 2022 to August 2025, the trial randomized 374 participants out of 2268 approached. The last participant is expected to complete all procedures by the end of 2026 and final results will follow.

Conclusions:

Findings will inform whether any of these intervention strategies (and/or their combinations) can improve PA levels and diet quality in cancer survivors at increased risk of CVD. Clinical Trial: Clnicaltrials.gov NCT05075759