AUTHOR=Liu Hui-Pu , Wei James Cheng-Chung , Yip Hei-Tung , Yeh Ming-Hsin 

TITLE=Association of Insomnia, Depressive Disorders, and Mood Disorders as Risk Factors With Breast Cancer: A Nationwide Population-Based Cohort Study of 232,108 Women in Taiwan

JOURNAL=Frontiers in Oncology

VOLUME=Volume 11 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2021.757626

DOI=10.3389/fonc.2021.757626

ISSN=2234-943X

ABSTRACT=Background 
Insomnia, depressive disorders, and to a more general view, mood disorders are raising people’s concerns and causing disability of life. Herein, we try to seek the association of such illnesses with subsequent breast cancer.  
Methods 
This population-based, retrospective cohort study used data from Taiwan National Health Insurance Research Database. This study included 232,108 women diagnosed with insomnia, depressive disorders, and mood disorders from January 1, 2000, to December 31, 2013. Physician-diagnosed insomnia, depressive disorders, or mood disorders defined using outpatient and inpatient records before diagnosis of breast cancer. Cox proportional hazards regression analysis adjusted for women with insomnia, depressive disorders, mood disorders, and other factors like insured amount, urbanization, comorbidities had subsequent breast cancer. 
Results 
Sleeping medication was associated with a significantly increased incidence rate of breast cancer (aHR=1.23; 95% CI=1.13, 1.35; p<0.001). Insomnia was associated with significant increased hazard of breast cancer (aHR=1.16; 95% CI=1.07, 1.27; p<0.001). Annual insured amount > 20,000(TWD), high urbanization area, and hyperlipidemia were associated with increased hazard of breast cancer (aHR=1.13; 95% CI=1.01, 1.27; p=0.04, aHR=1.41; 95% CI=1.17, 1.71; p<0.001, aHR=1.14; 95% CI=1.02, 1.29; p=0.02, respectively). There was a positive correlation between depressive disorders and increased incidence rate of breast cancer but not statistically significant (aHR=1.11; 95% CI=0.99, 1.25; p=0.08). Mood disorders were not associated with increased hazard (aHR=1.11; 95% CI=0.91, 1.34; p=0.31).  
Conclusion 
In this study, women with insomnia had increased risk of breast cancer, particularly those in high urbanization or with high insured amounts. Sleeping medication (BZD or non-BZD) and hyperlipidemia were independently associated with a higher hazard ratio of breast cancer. Insomnia along with sleeping medication did not yield more hazards than each alone. Mood disorders appeared to be not associated with subsequent breast cancer.  However, depressive disorders, the subgroups of mood disorders, could possibly increase the incidence rate of breast cancer though not statistically significant.