Low-Dose Tamoxifen to Prevent Recurrence in Patients With Breast Noninvasive Neoplasia: 10-Year Follow-up of TAM-01 Trial

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As reported in the Journal of Clinical Oncology by Lazzeroni et al, the 10-year follow-up of the Italian phase III TAM-01 trial has shown that 3 years of low-dose tamoxifen vs placebo continued to be associated with a reduced risk of recurrence of invasive breast cancer or ductal carcinoma in situ in patients with intraepithelial neoplasia.

Study Details

In the multicenter trial, 500 patients with breast intraepithelial neoplasia (atypical ductal hyperplasia, lobular carcinoma in situ, or hormone-sensitive or unknown ductal carcinoma in situ) were randomly assigned to receive tamoxifen at 5 mg once daily (n = 253) or placebo (n = 247) for 3 years after surgery with or without radiotherapy. Among the total population, 20% had atypical ductal hyperplasia, 11% had lobular carcinoma in situ, and 69% had ductal carcinoma in situ. Mean age at the start of treatment was 54 years and 58% of patients were postmenopausal.

The primary endpoint was the incidence of invasive breast cancer or ductal carcinoma in situ. Results at 5 years showed a 52% reduction in recurrence of invasive breast cancer or ductal carcinoma in situ with tamoxifen, with no excess of adverse events vs placebo.

Key Findings

After a median follow-up of 9.7 years (interquartile range = 8.3–10.9 years), 66 breast cancers were diagnosed in the entire population, including 15 in situ and 51 invasive cases. A total of 25 were in the tamoxifen group and 41 in the placebo group, yielding annual rates per 1,000 person-years of 11.3 vs 19.5 (hazard ratio [HR] = 0.58, 95% confidence interval [CI] = 0.35–0.95, P = .03).

Most recurrences were invasive (77%) and ipsilateral (59%). Contralateral breast cancer was observed in 6 patients in the tamoxifen group vs 16 in the placebo group (HR = 0.36, 95% CI = 0.14–0.92, P = .025).

Among patients with ductal carcinoma in situ at baseline, tamoxifen significantly reduced the risk of invasive disease vs placebo (HR = 0.50, 95% CI = 0.28–0.91, P = .02). The number needed to treat with tamoxifen to prevent one recurrence was 22 at 5 years and 14 at 10 years.

No differences between groups were observed in the incidence of serious adverse events during prolonged follow-up.

The investigators concluded, “Tamoxifen [at] 5 mg once daily for 3 years significantly prevents recurrence from noninvasive breast cancer after 7 years from treatment cessation without long-term adverse events.”

Andrea DeCensi, MD, of the Division of Medical Oncology, Ente Ospedaliero Ospedali Galliera, Genoa, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was supported by the Italian Ministry of Health, Italian Association for Cancer Research, and others. For full disclosures of the study authors, visit

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