Positive affect and inflammation in women with breast cancer: A systematic review

Positive affect has been implicated in psychobiological processes relevant to cancer adaptation and survivorship. However, evidence linking positive affect to objective inflammatory and immune-related biomarkers in women with breast cancer remains limited, fragmented, and methodologically heterogeneous. This systematic review was conducted to provide a focused and transparent synthesis of studies examining associations between positive affect and inflammatory or immune-related outcomes in this population.

Five electronic databases were systematically searched. The review protocol was prospectively registered in PROSPERO (CRD420261304159). Studies were included if they assessed positive affect using validated measures and reported at least one objective inflammatory or immune-related biomarker in women with breast cancer. Observational studies and randomized controlled trials were eligible. Six studies met predefined PICO criteria.

Six studies examined associations between positive affect and inflammatory or immune-related outcomes across treatment and survivorship phases. Higher low-arousal positive affect was associated with lower C-reactive protein (CRP) in longitudinal analyses. Randomized controlled trials of Mindful Awareness Practices increased positive affect and meaning-related well-being; effects on circulating interleukin-6 (IL-6) and CRP were inconsistent, whereas transcriptional analyses indicated reduced or buffered pro-inflammatory gene expression. Increases in eudaimonic well-being were linked to reductions in conserved transcriptional response to adversity (CTRA) profiles. Affiliative positive emotions were associated with enhanced T helper type 1 (Th1)-type cytokine production.

Current evidence suggests that positive affect may be associated with reduced inflammatory activity or more adaptive immune functioning in women with breast cancer. However, heterogeneity in affect conceptualization and biomarker assessment underscores the need for larger, methodologically harmonized longitudinal and intervention studies.