Associations between breast cancer survivorship and adverse mental health outcomes: A matched population-based cohort study in the United Kingdom

Breast cancer is the most common cancer diagnosed in women globally, and 5-year net survival probabilities in high-income countries are generally >80%. A cancer diagnosis and treatment are often traumatic events, and many women struggle to cope during this period. Less is known, however, about the long-term mental health impact of the disease, despite many women living several years beyond their breast cancer and mental health being a major source of disability in modern societies. The objective of this study was to quantify the risk of several adverse mental health-related outcomes in women with a history of breast cancer followed in primary care in the United Kingdom National Health Service, compared to similar women who never had cancer. We conducted a matched cohort study using data routinely collected in primary care across the UK to quantify associations between breast cancer history and depression, anxiety, and other mental health-related outcomes. All women with incident breast cancer in the Clinical Practice Research Datalink (CPRD) GOLD primary care database between 1988 and 2018 (N = 57,571, mean = 62 ± 14 years) were matched 1:4 to women with no prior cancer (N = 230,067) based on age, primary care practice, and eligibility of the data for linkage to hospital data sources. Cox models were used to estimate associations between breast cancer survivorship and each mental health-related outcome, further adjusting for diabetes, body mass index (BMI), and smoking and drinking status at baseline. Breast cancer survivorship was positively associated with anxiety (adjusted hazard ratio (HR) = 1.33; 95% confidence interval (CI): 1.29-1.36; p < 0.001), depression (1.35; 1.32-1.38; p < 0.001), sexual dysfunction (1.27; 1.17-1.38; p < 0.001), and sleep disorder (1.68; 1.63-1.73; p < 0.001), but not with cognitive dysfunction (1.00; 0.97-1.04; p = 0.88). Positive associations were also found for fatigue (HR = 1.28; 1.25-1.31; p < 0.001), pain (1.22; 1.20-1.24; p < 0.001), receipt of opioid analgesics (1.86; 1.83-1.90; p < 0.001), and fatal and nonfatal self-harm (1.15; 0.97-1.36; p = 0.11), but CI was wide, and the relationship was not statistically significant for the latter. HRs for anxiety and depression decreased over time (p-interaction