Quality of life (QoL) is a central outcome for people living with metastatic breast cancer (MBC). This study examined daily-life QoL using ecological momentary assessment (EMA) to capture both between-person differences and within-person fluctuations in symptom severity and positive affect. The aim was to identify which symptoms and positive affect domains relate to QoL differences across individuals and to QoL changes within individuals over time.
From 2023 to 2024, patients with MBC were recruited from five Mid-Atlantic clinical sites. Eligibility required English or Spanish fluency, life expectancy greater than six months, and access to a smartphone. Participants were invited to complete 12 EMA surveys over a 4-week period.
EMA items collected at each prompt included a global QoL rating, nine symptom severity items (depression, anxiety, pain, fatigue, slowed cognition, appetite loss, nausea, gastrointestinal distress, and decreased libido), and three positive affect items (social connection, peace, and joy). The dataset therefore allowed repeated measures within individuals and comparison across the cohort.
The investigators used multilevel mixed-effects models to analyze relationships between QoL and symptom severity and positive affect. Models distinguished between-person effects (how individuals who generally report more severe symptoms or lower positive affect differ in QoL from other individuals) and within-person effects (how an individual's QoL varies at times when their symptoms or positive affect deviate from their own average). The study also explored associations between QoL and years since MBC diagnosis at study entry, and assessed baseline demographic correlates of QoL estimates.
The analytic sample included 108 participants with a mean age of 57.8 years. On average participants were 4.4 years post-MBC diagnosis (range 0.06 to 20.65 years). Additional baseline sociodemographic and clinical details are reported in the source; effect estimates for some baseline predictors are presented in the abstract.
Between-person analyses examined whether individuals who typically reported higher symptom severity or lower positive affect also reported lower QoL compared with peers. The source reports two significant between-person associations: higher typical nausea was associated with worse QoL (β = -0.109, p = 0.035), and lower typical joy was associated with worse QoL (β = 0.593, p < 0.001). These findings indicate that individuals who, on average, experienced more nausea or less joy had poorer overall QoL compared with other participants.
Within-person analyses tested whether departures from an individual's usual symptom or affect level coincided with concurrent changes in QoL. The source reports multiple significant within-person associations. QoL was lower at times when an individual reported greater-than-usual depression (β = -0.177, p < 0.001), anxiety (β = -0.049, p = 0.023), fatigue (β = -0.052, p = 0.009), appetite loss (β = -0.053, p = 0.028), and decreased libido (β = -0.058, p = 0.036). Conversely, QoL was higher at times when an individual reported greater-than-usual social connectedness (β = 0.091, p = 0.001), peace (β = 0.107, p < 0.001), and joy (β = 0.055, p = 0.047). These within-person effects emphasize that short-term symptom worsening and reductions in positive affect are associated with contemporaneous declines in QoL for the same person.
In the analyses reported by the source, QoL was not associated with years since MBC diagnosis (β = 0.106, p = 0.956), indicating no detectable linear relationship between time since diagnosis and EMA-measured QoL within this sample. Baseline predictors reported in the abstract included age and partnership status: older age (β = 0.482, p = 0.013) and being partnered (β = 13.356, p = 0.005) were positively associated with estimated QoL at MBC diagnosis. The source also reports that changes in QoL per year since diagnosis were positively associated with being employed at baseline (β = 2.453, p < 0.001) and were negatively associated with another predictor; however, the source text available here is truncated and the remainder of that specific result was not reported in the provided material.
The public source text includes the abstract and author and affiliation metadata; portions of the results were truncated in the source file provided here. As a result, some specific estimates and the full description of certain associations (for example, the variable negatively associated with QoL change per year mentioned at the end of the abstract) are not available from the excerpt. Detailed methods (sample heterogeneity, EMA adherence rates, instrument scaling and scoring), full multivariable model specifications, and secondary analyses are reported in the full article but were not present in the provided source excerpt.
Findings underscore that both stable between-person differences (notably nausea and joy) and short-term within-person fluctuations in symptoms and positive affect meaningfully relate to QoL in adults with metastatic breast cancer. Routine, repeated assessment—such as EMA—can reveal clinically relevant within-person changes that may be missed by cross-sectional or clinic-only assessments. Interventions to reduce symptom burden (depression, anxiety, fatigue, appetite loss, decreased libido, nausea) and to support positive affect (social connectedness, peace, joy) may help maintain or improve QoL in this population. Future reports of the full manuscript are needed to review complete model specifications, sensitivity analyses, and other details not present in the abstract excerpt.