BACKGROUND: Psychological distress is prevalent in patients with breast cancer and is viewed as a non-pathological occurrence. Severe distress and mental disorder display a substantial overlap in both conceptual contexts and studies in oncological settings. A domain that may contribute to distinguishing non-pathological distress from signs of potential disorder is the transiency of distress.

AIM: To examine the transiency of distress response in breast cancer patients by investigating the changes in clinical caseness of depression and anxiety during one year following surgery.

METHODS: Data on the Hospital Anxiety and Depression Scale from a cohort of 715 women with breast cancer on three assessments within one year following breast surgery were subjected to Generalized Estimation Equation Analysis, McNemar's test, and logistic regression.

RESULTS: There was a significant decrease in the proportions of anxiety cases from baseline (37.7%) to 4 months (26.7%) but no significant change from 4 to 12 months. Caseness in depression significantly increased from baseline (18.5%) to 4 months (21.5%) but decreased to 15.3% at 12 months. Only experience of major adverse life events contributed to 12 months caseness of anxiety and depression beyond baseline caseness.

DISCUSSION: The average decrease in caseness of anxiety and depression a year following surgery lends support to the view of distress as a transient non-pathological response. A subgroup of patients, however, displayed enduring or recurrent severe distress indicating the presence of potential disorder. The findings emphasize the importance of screening and follow up monitoring of distress.