ArticleBMC cancer2026
Endocrine therapy and COVID-19 outcomes in women with breast cancer: a nationwide register- based matched cohort study.
Article in BMC cancer, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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Abstract
purposeThe COVID-19 pandemic posed substantial challenges to cancer care, raising concerns about the safety of ongoing endocrine therapy in women with breast cancer. However, real-world evidence on the association between endocrine therapy and COVID-19 outcomes in population-based cohorts remains limited.
methodsA nationwide, register-based matched cohort study was conducted in Sweden, including women aged ≥ 55 years who received endocrine therapy for breast cancer during 2020. A total of 31,678 women were included: 8,879 treated with tamoxifen, 21,384 with aromatase inhibitors, and 1,415 with sequential therapy. Exposed women were matched 1:1 by age and region to population controls without breast cancer or estrogen-modulating therapy. Stage-stratified analyses were performed for early-stage and locally advanced breast cancer. Outcomes included COVID-19-related mortality (primary outcome), all-cause mortality, intensive care unit admission, COVID-19-related hospitalization, and laboratory-confirmed SARS-CoV-2 infection.
resultsCOVID-19-related mortality did not differ between women receiving endocrine therapy and their matched population controls. Intensive care unit admission risk were comparable across groups. Tamoxifen was associated with lower all-cause mortality in early-stage breast cancer, whereas aromatase inhibitors were linked to higher all-cause mortality and increased COVID-19-related hospitalization in locally advanced disease. A modestly increased risk of SARS-CoV-2 infection was observed among tamoxifen users.
conclusionIn this nationwide Swedish cohort, adjuvant endocrine therapy was not associated with increased COVID-19-specific mortality. These findings support the continued use of adjuvant endocrine therapy in women with breast cancer without added COVID-19 mortality risk and highlight stage-specific differences in outcomes, reinforcing the safety of endocrine therapy during pandemic conditions.
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