Kefah Mokbel, Chair of Breast Cancer Surgery at London Breast Institute and Honorary Professor of Medicine at Cardiff University School of Medicine, shared a post on LinkedIn:
“Surgery-free Tamoxifen for low-risk DCIS – fell short of the safety bar
LORETTA (JCOG1505) – single-arm prospective study of tamoxifen 20 mg daily (no surgery) in 341 women with ER+, HER2–, low-risk DCIS (≤25 mm, no comedo necrosis; imaging negative for invasion) – was stopped early because the 5-year cumulative incidence of ipsilateral invasive breast cancer was 9.8% (95% CI 5.2–16.1), exceeding the prespecified safety threshold of 7%. Key outcomes: 5-yr surgery-free survival 82%; surgical conversion 9.7%; 5-yr OS 98.8%; grade ≥3 AEs 3.8%.
SABCS 2025, Abstract GS2-09
Interpretation
Tamoxifen-only management did not meet the trial’s safety criteria and therefore should not be adopted broadly. However, it should be noted that breast cancer–specific survival was 100% with no deaths attributable to breast cancer.
It may be a reasonable option only for highly selected patients who strictly match trial criteria – e.g., small, screen-detected, ER-positive, HER2-negative, grade 1 DCIS (≤15mm, no comedo necrosis), or patients with prohibitive surgical risk – but only after explicit counselling about the ~10% 5-yr invasive risk and close surveillance.”
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