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Long-term Follow-up of the TAM-01 Study and Pooled Analysis of Low-dose Tamoxifen Studies in Non-invasive or Microinvasive Breast Neoplasms

NCT06982313 · Status: COMPLETED · Type: OBSERVATIONAL · Enrollment: 1545

Last updated 2026-03-11

No results posted yet for this study

Summary

Low-dose tamoxifen (5 mg/day for three years, BabyTam) has emerged as a safer and effective alternative to the standard regimen (20 mg/day), reducing breast cancer recurrence with fewer adverse events. The TAM-01 phase III trial demonstrated a 42% reduction in breast cancer events over ten years compared to placebo in women with ductal carcinoma in situ (DCIS) or high-risk lesions (HRL, ADH, LCIS), supporting its inclusion in clinical guidelines.

The phase III TAM-01 trial enrolled 500 women, comparing low-dose tamoxifen to placebo over three years, with a median follow-up of 9.7 years (IQR, 8.3-10.9). Results showed a significant reduction in invasive breast cancer (HR = 0.58; 95% CI: 0.35-0.95; p = 0.03) and in contralateral breast cancer, CBC (HR = 0.36; 95% CI: 0.14-0.92; p = 0.025), with no increase in serious adverse events.

Exploratory analyses suggested a greater benefit in postmenopausal women (HR = 0.30; 95% CI: 0.11-0.82), compared to premenopausal women (HR = 0.73; 95% CI: 0.30-1.76), though this interaction did not reach statistical significance (p-interaction = 0.13). However, our unpublished data indicate a remarkable reduction of CBC in premenopausal women on BabyTam.

The TAM-01 long-term follow-up study aims to extend the follow-up of TAM-01 participants, evaluating long-term outcomes, including incidence of invasive breast cancer and DCIS, with a focus on tumor laterality and menopausal status, as well as to assess other non-invasive events (LCIS, ADH, or ALH) and adverse outcomes of special interest.

We will also perform a pooled analysis of our three low-dose tamoxifen studies to increase the statistical power of our findings, with special attention to the effect according to menopausal status and site of recurrence. The primary endpoint will be the breast cancer-free interval.

The findings are expected to strengthen the evidence supporting low-dose tamoxifen as a viable prevention strategy in high-risk populations with intraepithelial neoplasia (IEN or DCIS+HRLs) or microinvasive disease.

Conditions

  • Breast Cancer Invasive

Interventions

DRUG

Tamoxifen (Nolvadex) placebo

Tamoxifen (Nolvadex) placebo per day for 3 years during TAM-01 phase III trial.

DRUG

Tamoxifen (Nolvadex)

5 mg per day for 3 years during TAM-01 phase III trial

Sponsors & Collaborators

  • Fundacao Champalimaud

    collaborator OTHER

  • European Institute of Oncology

    collaborator OTHER

  • Ente Ospedaliero Ospedali Galliera

    lead OTHER

Principal Investigators

  • Andrea De Censi, MD · Champalimaud Foundation - Champalimaud Clinical Center

Eligibility

Min Age
18 Years
Sex
FEMALE
Healthy Volunteers
No

Timeline & Regulatory

Start
1996-07-01
Primary Completion
2026-03-01
Completion
2026-03-08

Countries

  • Italy

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT06982313 on ClinicalTrials.gov