Incidence and temporal trends of depression and anxiety following cancer diagnosis in Japan: Insights from the <scp>LIFE</scp> study

Depression and anxiety are common among cancer patients and are associated with poorer treatment adherence, quality of life, and survival outcomes. While the prevalence of these conditions has been widely reported, less is known about their incidence and temporal trends. This study aimed to clarify the incidence and temporal patterns of depression and anxiety following cancer diagnosis using claims data from 14 Japanese municipalities. The study cohort comprised 22,863 newly diagnosed cancer patients from April 2018 to March 2021. During a follow-up period of up to 24 months after diagnosis, we identified depression and anxiety using recorded diagnoses in the claims data. We calculated crude incidence rates, and then Poisson regression was used to visualize monthly incidence rates and temporal trends for all patients, as well as according to sex, age, treatment modality, and cancer type. The overall crude incidence rates were 3.36 and 3.11 per 1000 person-months for depression and anxiety, respectively. Depression incidence peaked around the second month following cancer diagnosis, while anxiety incidence peaked in the month of cancer diagnosis. Female sex and chemotherapy were associated with higher incidence rates for depression and anxiety. Pancreatic cancer showed the highest incidence rates for both disorders. These findings provide valuable insights into the burden and timing of mental disorders among cancer patients in Japan and emphasize the need for targeted interventions during high-risk periods.