Lo Tam Trial Study Arms
The Lo Tam (TAM-01) trial randomized 500 women with breast intraepithelial neoplasia to receive either low-dose tamoxifen (5 mg once daily) or placebo for 3 years 1.
Trial Design
The TAM-01 study was a phase III, randomized, placebo-controlled trial that enrolled women with breast noninvasive disease following surgery with or without radiation 1. The two study arms were:
- Tamoxifen arm: Low-dose tamoxifen 5 mg once daily for 3 years
- Placebo arm: Matching placebo for 3 years
Patient Population
The 500 enrolled women had the following baseline characteristics 1:
- 69% had DCIS (ductal carcinoma in situ)
- 20% had atypical ductal hyperplasia
- 11% had LCIS (lobular carcinoma in situ)
- Mean age: 54 ± 9 years
- 58% were postmenopausal
All participants had hormone-sensitive or unknown receptor status intraepithelial neoplasia.
Key Efficacy Results
After median follow-up of 9.7 years, the low-dose tamoxifen arm demonstrated 1:
- 42% reduction in breast cancer recurrence (HR 0.58; 95% CI 0.35-0.95; P=0.03)
- Annual rate: 11.3 per 1,000 person-years with tamoxifen vs 19.5 with placebo
- 64% reduction in contralateral breast cancer (HR 0.36; 95% CI 0.14-0.92; P=0.025)
- 50% reduction in DCIS cohort specifically (HR 0.50; 95% CI 0.28-0.91; P=0.02)
The number needed to treat was 22 at 5 years and 14 at 10 years 1.
Safety Profile
No significant difference in serious adverse events was reported between arms during the prolonged follow-up period 1. This represents a major advantage over standard 20 mg daily dosing, which carries higher risks of endometrial cancer, thromboembolic events, and vasomotor symptoms 2.