Breast cancer patients and caregiver inter- and intrapersonal spillover effects on anxiety, depression, pain, and fatigue during the first year of treatment.

Purpose: Breast cancer patients and caregivers experience anxiety, depression, fatigue, and pain symptoms during treatment. The present study sought to determine which times during the first year of breast cancer treatment have the greatest risk of interpersonal spillover on patient and caregiver symptoms.

Methods: Self-report survey data were collected from 55 estrogen-receptor positive (ER+) stage I-III breast cancer patients and their identified caregivers throughout the first year of primary treatment (e.g., surgery, radiation) to assess symptoms of biobehavioral reactivity (i.e., anxiety, depression, fatigue, and pain). Surveys from patients and caregivers were provided at baseline (before treatment), 6 weeks after surgery, 6 months after surgery, and 12 months after surgery. The present sample comprised primarily white, middle-income individuals with an average age of 63 years old. Data were analyzed using longitudinal Actor-Partner Interdependence Modeling in Mplus.

Results: Intrapersonally, preceding symptoms predicted poor future functioning for both patients and caregivers across the majority of time points. Interpersonally, patients' anxiety at 6 weeks (p = .04) and fatigue at baseline (p = .01) and 6 months (p = .04) predicted greater caregiver symptoms at the subsequent clinically relevant times. However, concurrent spillover occurs for all of the measures of biobehavioral reactivity at one or more times during treatment.

Conclusion: Anxiety and fatigue are vulnerable to longitudinal interpersonal "spillover" of symptoms, particularly for caregivers, starting early in treatment. We also find in this pilot study that concurrent biobehavioral reactivity symptom spillover occurs in some form throughout the first year of breast cancer treatment. It is common for interventions that target symptoms of biobehavioral reactivity to focus on the individual patient. However, given the degree of longitudinal and concurrent spillover observed between breast cancer patients and caregivers, we recommend future research test behavioral interventions that teach dyadic coping skills in addition to replicating findings with a fully powered prospective study.