- Low-dose tamoxifen (5 mg/day for 3 years) halves recurrence of hormone receptor (HR)-positive breast intraepithelial neoplasia with limited toxicity.
Why this matters
- Low-dose tamoxifen offers a new treatment option for breast intraepithelial neoplasia, a condition that increases risk for invasive breast cancer 5- to 10-fold.
- Multicenter, double-blinded, randomized controlled trial (RCT) of low-dose tamoxifen (n=253) vs placebo (n=247) in women who had undergone surgery for breast intraepithelial neoplasia, including atypical ductal hyperplasia and lobular or ductal carcinoma in situ (DCIS).
- Primary outcome was neoplastic events (invasive breast cancer or DCIS).
- Funding: Italian Ministry of Health; others.
- Median follow-up was 5.1 years.
- Low-dose tamoxifen yielded 52% fewer neoplastic events vs placebo (11.6 vs 23.9/1000 person-years; HR, 0.48; P=.02).
- Low-dose tamoxifen yielded 75% fewer neoplastic events in the contralateral breast vs placebo (HR, 0.25; P=.02).
- No differences between groups in patient-reported outcomes, except for a small increase in the frequency of daily hot flashes with low-dose tamoxifen vs placebo (P=.02).
- Low-dose tamoxifen was associated with fewer serious adverse events; they included 1 deep vein thrombosis and 1 stage I endometrial cancer.
- Fewer than planned breast events.