Relationship satisfaction predicts lower stress and inflammation in breast cancer survivors: A longitudinal study of within-person and between-person effects.

Background: Breast cancer survivors with elevated inflammation have a greater risk for cancer recurrence, premature mortality, and comorbid disease development. The psychological stress survivors experience when confronted with a breast cancer diagnosis and cancer treatment can heighten inflammation. Identifying factors that reduce stress and inflammation could lead to improvements in survivors' long-term health. Accordingly, this study examined the health-enhancing effects of romantic relationships-a key health determinant-on breast cancer survivors' stress and inflammation.

Methods: Breast cancer survivors (n = 139, stages 0-IIIC) completed a baseline visit before treatment and two follow-up visits 6 and 18 months after treatment ended. Women completed self-report questionnaires assessing their romantic relationship satisfaction and perceived stress, and they provided a blood sample for serum markers of inflammation at each visit. The longitudinal design allowed for examination within and between survivors. We conducted multilevel mediation analyses to assess how changes in survivors' relationship satisfaction were related to changes in stress and inflammation from visit to visit (i.e., within-person effects), as well as how the average effects of relationship satisfaction were associated with average stress and inflammation levels throughout the study (i.e., between-person effects).

Results: At the within-person level, at visits in which survivors were more satisfied with their relationships, they also perceived less stress, which in turn was related to lower than their own average levels of serum C-reactive protein and proinflammatory cytokines (tumor necrosis factor-α, interleukin-6, and interleukin-1β). At the between-person level, survivors who had greater relationship satisfaction throughout the study had lower perceived stress, which was linked to lower levels of inflammation.

Conclusion: Breast cancer survivors in satisfying romantic relationships felt less stressed and in turn had lower inflammation throughout cancer treatment. This study illustrates the utility of a within-person approach to not only consider the average effects of relationship satisfaction, but also how changes in their own relationship satisfaction impact stress and inflammation over time. Our findings demonstrate important psychological and immunological pathways through which satisfying relationships may promote breast cancer survivors' long-term health.