Affective morbidity after cancer diagnosis: Nationwide incidence and pharmacotherapy patterns across five major cancer types.

[BACKGROUND] Psychiatric morbidity after cancer diagnosis impairs quality of life and may worsen survival. Cancer-type-specific risks and real-world pharmacotherapy patterns in Asian populations remain incompletely defined. We estimated the post-diagnosis incidence of depression, anxiety disorder, and adjustment disorder in five common cancers and characterized psychotropic treatment using dose-standardized exposure.

[METHODS] Nationwide Korean claims from the Health Insurance Review and Assessment Service were used to assemble incident cohorts of thyroid, colorectal, lung, breast, and gastric cancers. Psychiatric outcomes after diagnosis were identified, and hazard ratios were estimated with multivariable Cox models adjusting for age, sex, socioeconomic status, and comorbidity. Among patients with any diagnosis, psychotropic utilization and dose-standardized exposure were summarized using WHO-defined daily dose metrics.

[RESULTS] The cohort included 550,829 patients. The post-diagnosis incidence was 12.1% for depression (range by cancer 9.4-14.6%), 13.3% for anxiety disorder (11.5-15.8%), and 1.7% for adjustment disorder (1.2-2.9%), with the highest burden for breast and lung cancer and the lowest for thyroid cancer. Female, older age, lower economic status, and higher comorbidity were associated with increased risk for psychiatric disorders across cancer types. Among those diagnosed, antidepressant use was 43% and benzodiazepine use was 70%, with higher dose-standardized benzodiazepine exposure.

[CONCLUSIONS] Affective disorders after cancer diagnosis were common but cancer-type specific, with higher risk in vulnerable subgroups. Pharmacotherapy was marked by high benzodiazepine use and comparatively lower antidepressant treatment and exposure. These findings support cancer type and risk stratified screening, linkage to mental health care, and guideline concordant treatment, including benzodiazepine stewardship.