Emotional Functioning as a Dimension of Quality of Life in Breast Cancer Survivors: A Systematic Review and Meta-Analysis

<b>Background</b>: As survival rates among breast cancer (BC) patients continue to rise, Emotional Functioning (EF)-has become increasingly clinically relevant; however, researchers have yet to fully characterize its long-term, dynamic trajectories following surgery. This systematic review and meta-analysis aimed to (1) characterize the longitudinal trajectories of EF after BC surgery and (2) examine the moderating effects of surgical modality and age. <b>Methods</b>: We conducted this systematic review and meta-analysis in accordance with PRISMA 2020 guidelines. We synthesized data from studies published between 2000 and 2024 that assessed EF using the EORTC QLQ-C30 at multiple post-surgical time points. Using multilevel random-effects meta-analytic models, we examined EF trajectories across 116 effect sizes derived from 40 studies, and evaluated time, surgical modality (breast-conserving surgery (BCS), mastectomy (MA), mastectomy with immediate reconstruction (Mx + IR) and age group as moderators. <b>Results</b>: The overall pooled estimate for EF was 73.44 (95% CI: 70.29-76.58, <i>p</i> < 0.001). Time since surgery significantly influenced EF: scores were lowest during the initial 6 months (66.82, 95% CI: 59.75-73.89), peaked at 7-15 months (77.86, 95% CI: 74.51-81.22) and 31-54 months (77.52, 95% CI: 70.44-84.59), and showed lower values at 16-30 months (72.58, 95% CI: 61.45-83.72) and 55-72 months (69.81, 95% CI: 64.08-75.54). Surgical modality significantly shaped these trajectories (<i>p</i> = 0.013). The overall pooled estimate for EF was 73.44 (95% CI: 70.29-76.58, <i>p</i> < 0.001). Time since surgery significantly influenced EF: scores were lowest during the initial 6 months (66.82, 95% CI: 59.75-73.89), peaked at 7-15 months (77.86, 95% CI: 74.51-81.22) and 31-54 months (77.52, 95% CI: 70.44-84.59), and showed lower values at 16-30 months (72.58, 95% CI: 61.45-83.72) and 55-72 months (69.81, 95% CI: 64.08-75.54). Surgical modality significantly shaped these trajectories (<i>p</i> = 0.013). The BCS group showed a significant inverted-U trajectory in EF scores, with a positive linear slope (β = 1.22, SE = 0.50, <i>p</i> = 0.046) and a small negative quadratic term (β = -0.02, SE = 0.01, <i>p</i> = 0.046), indicating initial improvement followed by decline. A similar pattern was observed for MA, where the linear term (β = 1.19, SE = 0.51, <i>p</i> = 0.054) and quadratic curvature (β = -0.02, SE = 0.01, <i>p</i> = 0.054) suggested an early rise with subsequent decline. In contrast, Mx + IR displayed a high intercept (β = 71.46, SE = 4.46, <i>p</i> < 0.001) but no significant trajectory over time (<i>p</i> = 0.582), indicating stability. The 45-60 year group demonstrated a significant inverted-U trajectory in EF scores, with a positive linear coefficient (β = 0.87, SE = 0.38, <i>p</i> = 0.067) and a negative quadratic coefficient (β = -0.01, SE = 0.01, <i>p</i> = 0.067), suggesting an early rise in emotional functioning followed by a subsequent decline. Participants <45 years also showed a significant inverted-U pattern, starting from a moderately high baseline (β = 67.56, SE = 4.26, <i>p</i> < 0.001) with a positive linear slope (β = 0.82, SE = 0.34, <i>p</i> = 0.051) and a negative quadratic curvature (β = -0.01, SE = 0.01, <i>p</i> = 0.051). In contrast, the >60 year group reported the highest baseline scores (β = 75.60, SE = 5.18, <i>p</i> < 0.001) with no significant trajectory, indicating overall stability. These findings confirm that EF follows a significant inverted-U trajectory (<i>p</i> < 0.001) and is influenced by time, surgical modality, and age.