Coping With Side Effects: A Daily Diary Study in Women With Breast Cancer Living With Adjuvant Endocrine Therapy

Objective Adjuvant endocrine therapy (AET) is increasingly being prescribed for up to 10 years to people diagnosed with hormone receptor‐positive breast cancer. AET intake is often accompanied by side effects that significantly impact the well‐being of people. The way individuals cope with medication‐related side effects might play a pivotal role in their emotional adaption. Methods This intensive‐longitudinal study investigated the association between self‐reported coping strategies (Brief COPE) and psychological well‐being (Patient Health Questionnaire‐4) among women undergoing AET. A multilevel factor analysis resulted in the identification of four coping factors, namely, problem‐focused, support‐focused, meaning‐focused, and avoidance‐focused coping. Daily coping efforts and experienced side effects were analyzed as predictors of psychological well‐being using multilevel modeling. Results A total of 215 women (Mage = 56.5 ± 10.9 years) participated, resulting in a total of n = 2080 daily surveys (M = 9.67 ± 1.08). On average, women reported 3.7 ± 2.2 different side effects per day. Days characterized by an elevated frequency of side effects and increased burden were associated with diminished well‐being. Using more problem‐ and meaning‐focused strategies than usual to cope with side effects correlated positively with well‐being. Conversely, employing more support‐ and avoidance‐focused coping strategies than usual was linked to reduced psychological well‐being. Exploratory analyses focusing on individual coping strategies provided nuanced insights into coping behaviors. Conclusion The present findings underscore the relationship between women's coping efforts concerning medication‐related side effects during AET and their daily well‐being. Psychosocial education (e.g., cognitive behavioral therapy) may offer valuable benefits for patients by helping them develop adaptive coping strategies to manage side effects.