{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,28]],"date-time":"2026-04-28T21:24:51Z","timestamp":1777411491903,"version":"3.51.4"},"reference-count":25,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,2,2]],"date-time":"2026-02-02T00:00:00Z","timestamp":1769990400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100019476","name":"Siriraj Foundation","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100019476","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Current Oncology"],"abstract":"<jats:p>Background: Adjuvant tamoxifen reduces recurrence in patients with ER-positive DCIS treated with lumpectomy and radiation, but its benefit after mastectomy remains unclear. Methods: We retrospectively analyzed 287 patients who underwent mastectomy for pure DCIS at Siriraj Hospital between 2008 and 2017. Recurrence risk factors were assessed using log-rank test, and survival probabilities were estimated with Kaplan\u2013Meier analysis. Results: Of 180 patients with hormone receptor (HR)-positive pure DCIS treated with mastectomy, 120 (66.7%) received tamoxifen, while the remaining 60 (33.3%) did not. The median follow-up was 8.07 years (0.05\u201313.8 years). Sixteen (8.9%) recurrences were identified, with 5 in the tamoxifen group and 11 in non-endocrine-therapy (ET) group. The 10-year recurrence-free survival (RFS) was 94.7% in the tamoxifen group compared with 77.9% in the non-ET group. Patients with HR-positive DCIS treated with tamoxifen following mastectomy had significantly less subsequent breast cancer (HR = 0.178; p = 0.001). Conclusions: Recurrence of breast cancer after mastectomy for DCIS is rare; however, it carries a high mortality rate for those who relapse. Adjuvant tamoxifen after mastectomy demonstrated a significant reduction in the risk of recurrence in ER-positive DCIS. This study supports the decision to prescribe adjuvant ET in patients with DCIS who underwent mastectomy.<\/jats:p>","DOI":"10.3390\/curroncol33020089","type":"journal-article","created":{"date-parts":[[2026,2,3]],"date-time":"2026-02-03T10:48:01Z","timestamp":1770115681000},"page":"89","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Tamoxifen Reduces Breast Cancer Recurrence in Women with DCIS Who Underwent Mastectomy"],"prefix":"10.3390","volume":"33","author":[{"given":"Netchanok","family":"Sae-sim","sequence":"first","affiliation":[{"name":"Division of Head Neck and Breast Surgery, Department of Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Norasate","family":"Samarnthai","sequence":"additional","affiliation":[{"name":"Department of Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9027-7406","authenticated-orcid":false,"given":"Warapan","family":"Numprasit","sequence":"additional","affiliation":[{"name":"Division of Head Neck and Breast Surgery, Department of Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,2,2]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"134","DOI":"10.1093\/jncimonographs\/lgq035","article-title":"Ductal carcinoma in situ: Terminology, classification, and natural history","volume":"2010","author":"Allred","year":"2010","journal-title":"J. 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