{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T23:44:21Z","timestamp":1792107861682,"version":"4.4.0"},"reference-count":45,"publisher":"Oxford University Press (OUP)","license":[{"start":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T00:00:00Z","timestamp":1788998400000},"content-version":"am","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002794","name":"Swedish Cancer Society","doi-asserted-by":"publisher","award":["CAN 21 to 1660; CAN 24 to 0943 SIA; 21 to 0454 FE"],"award-info":[{"award-number":["CAN 21 to 1660; CAN 24 to 0943 SIA; 21 to 0454 FE"]}],"id":[{"id":"10.13039\/501100002794","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Kamprad Foundation","award":["20150052"],"award-info":[{"award-number":["20150052"]}]},{"DOI":"10.13039\/501100004359","name":"Swedish Research Council","doi-asserted-by":"publisher","award":["E0718301"],"award-info":[{"award-number":["E0718301"]}],"id":[{"id":"10.13039\/501100004359","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Tamoxifen reduces breast cancer incidence and recurrence, but uptake for primary prevention remains limited, largely because of concerns regarding adverse effects at the standard 20-mg dose. Understanding systemic endocrine effects of lower tamoxifen doses may help improve future prevention strategies.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We analyzed data from 1055 healthy women enrolled in the randomized, double-blind, placebo-controlled KARISMA trial (ClinicalTrials.gov identifier NCT03346200) assigned to either placebo or tamoxifen 1, 2.5, 5, 10, or 20\u2009mg daily for 6\u2009months. Plasma concentrations of endocrine biomarkers and tamoxifen metabolites were measured at study end. Associations between randomized tamoxifen dose, circulating metabolite concentrations, and endocrine biomarker plasma concentration (estrogens, androgens, progestogens, cortisol, prolactin, and sex hormone\u2013binding globulin [SHBG]) were evaluated.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Tamoxifen dose was associated with measurable endocrine changes after 6 months, most consistently increased SHBG levels, with additional associations observed for cortisol and hydroxyprogesterone. Sex hormone\u2013binding globulin demonstrated the clearest dose\u2013response relationship, with increasing levels across tamoxifen dose groups and evidence of attenuated increase at intermediate doses. Large relative differences between placebo and tamoxifen 20\u2009mg were additionally observed for estrone, estrone sulphate, and estradiol. Unadjusted analyses of circulating endoxifen showed broadly similar endocrine patterns; however, these associations were substantially attenuated after adjustment for randomized tamoxifen dose. Circulating tamoxifen metabolites were strongly correlated with administered dose and with one another.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Low-dose tamoxifen was associated with measurable endocrine changes, particularly in SHBG, cortisol, and hydroxyprogesterone. These findings show that endocrine pharmacodynamic responses during low-dose tamoxifen therapy warrant further investigation as a potential component of future individualized prevention and adjuvant endocrine therapy strategies.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Trial registration<\/jats:title>\n                    <jats:p>ClinicalTrials.gov: NCT03346200.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1093\/jnci\/djag321","type":"journal-article","created":{"date-parts":[[2026,9,9]],"date-time":"2026-09-09T11:54:29Z","timestamp":1788954869000},"source":"Crossref","is-referenced-by-count":0,"title":["Endocrine biomarker changes in a randomized low-dose tamoxifen trial for breast cancer prevention"],"prefix":"10.1093","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2086-1740","authenticated-orcid":false,"given":"Stephen","family":"Nash","sequence":"first","affiliation":[{"name":"Department of Medical 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Institutet, Karolinska University Hospital , Stockholm,","place":["Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0397-6538","authenticated-orcid":false,"given":"Magnus","family":"B\u00e4cklund","sequence":"additional","affiliation":[{"name":"Department of Medical Epidemiology and Biostatistics, Karolinska Institutet , Stockholm,","place":["Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8135-4270","authenticated-orcid":false,"given":"Mikael","family":"Eriksson","sequence":"additional","affiliation":[{"name":"Department of Medical Epidemiology and Biostatistics, Karolinska Institutet , Stockholm,","place":["Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sara","family":"Margolin","sequence":"additional","affiliation":[{"name":"Department of Oncology, S\u00f6dersjukhuset , Stockholm,","place":["Sweden"]},{"name":"Department of Clinical Science, Education S\u00f6dersjukhuset and Karolinska Institutet , Stockholm,","place":["Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Linda","family":"Thor\u00e9n","sequence":"additional","affiliation":[{"name":"Department of Oncology, S\u00f6dersjukhuset , Stockholm,","place":["Sweden"]},{"name":"Department of Clinical Science, Education S\u00f6dersjukhuset and Karolinska Institutet , Stockholm,","place":["Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7938-8893","authenticated-orcid":false,"given":"Signe","family":"Borgquist","sequence":"additional","affiliation":[{"name":"Department of Clinical Sciences Lund, Division of Oncology, Lund University and Sk\u00e5ne University Hospital , Lund,","place":["Sweden"]},{"name":"Department of Oncology, Aarhus University Hospital and Aarhus University , Aarhus,","place":["Denmark"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3233-5695","authenticated-orcid":false,"given":"Kamila","family":"Czene","sequence":"additional","affiliation":[{"name":"Department of Medical Epidemiology and Biostatistics, Karolinska Institutet , Stockholm,","place":["Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5640-9126","authenticated-orcid":false,"given":"Per","family":"Hall","sequence":"additional","affiliation":[{"name":"Department of Medical Epidemiology and Biostatistics, Karolinska Institutet , Stockholm,","place":["Sweden"]},{"name":"Department of Oncology, S\u00f6dersjukhuset , Stockholm,","place":["Sweden"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3171-1556","authenticated-orcid":false,"given":"Marike","family":"Gabrielson","sequence":"additional","affiliation":[{"name":"Department of 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