(30) Socioeconomic Position, Psychiatric Medical Treatment and Risk of Breast Cancer Recurrence and Mortality: A Danish Population-Based Cohort Study

Publication Number: 361

Background: Low socioeconomic position (SEP) among breast cancer patients has been associated with increased risk of recurrence and mortality. Yet, data on how psychiatric morbidity influences the association between SEP and breast cancer prognosis is scarce.

Objectives: To investigate the influence of prior psychiatric medical treatment on the association between SEP and breast cancer recurrence and mortality in a cohort of premenopausal women diagnosed with non-distant metastatic breast cancer in Denmark.

Methods: We conducted a nationwide cohort study, and cross-linked data from Danish registries on breast cancer, prescriptions for psychiatric medication, comorbidities, marital status, cohabitation, income, education, and employment. From the Danish Breast Cancer Group (DBCG) registry we assembled a cohort of all premenopausal women diagnosed with non-distant metastatic breast cancer between 2002 and 2011, who were aged <=54 years. We classified the women as prior users of psychiatric medication if before breast cancer diagnosis they had redeemed two or more prescriptions of psychiatric medication with one of the ATC codes: N05A (antipsychotics), N05B (anxiolytics) and N06A (antidepressants). We followed the women from the date of breast cancer surgery until death, emigration, recurrence, other malignancy, 10 years after diagnosis or 25th September 2017. Using Cox regression, we estimated hazard ratios (HR) and 95% confidence intervals associating SEP with (1) recurrence (including breast cancer-specific mortality) and (2) all-cause mortality, stratifying models according to prior use of psychiatric medication.

Results: The study cohort included 5,861 women. Of these, 976 developed recurrence and 857 women died during follow up (median 7 and 9 years of follow up, respectively). Women with low SEP had increased risk of recurrence and all-cause mortality. Among women with low education level, HRs of recurrence and mortality were higher among prior users of psychiatric medication than seen in women with no prior use, indicating potential effect-measure modification. No differences were observed for the remaining SEP exposures.

Conclusion: Psychiatric morbidity may partly explain the increased risk of recurrence and all-cause mortality seen in women with low education level. For the remaining SEP exposures, use of psychiatric medication prior to breast cancer diagnosis did not influence the association between SEP and breast cancer prognosis.