In a long-term individual patient-level pooled analysis reported in the Journal of Clinical Oncology, Gandini et al found that low-dose tamoxifen was associated with good outcomes in patients with noninvasive breast neoplasia.
Study Details
The study used individual patient data from three clinical studies involving women with estrogen receptor–positive or unknown ductal carcinoma in situ (DCIS), microinvasive carcinoma, or high-risk breast lesions. In the studies, patients received low-dose tamoxifen at 5 mg once daily or 10 mg once every other day for 2 to 5 years, or a control intervention (placebo or no intervention). The primary endpoint was breast cancer–free interval, defined as first occurrence of any ipsilateral or contralateral invasive breast cancer, DCIS, regional recurrence, or distant recurrence.
Key Findings
Among 1,545 women included in the analysis, median follow-up was 9.4 years.
Patients receiving low-dose tamoxifen had a reduced risk for breast cancer events overall, with a heterogeneity of treatment effect being observed according to menopausal status (P = .01).
Among postmenopausal women, breast cancer events occurred in 40 of 335 receiving low-dose tamoxifen vs 93 of 401 receiving control interventions (hazard ratio [HR] = 0.51, 95% confidence interval [CI] = 0.35–0.73, P < .001); low-dose tamoxifen was associated with a 10-year absolute reduction of 11.2% in breast cancer events.
Among premenopausal women, events occurred in 127 of 448 women receiving low-dose tamoxifen and in 107 of 335 receiving control interventions (HR = 0.90, 95% CI = 0.70–1.17, P = .45). A reduction in risk for contralateral breast cancer was observed with low-dose tamoxifen (HR = 0.45, 95% CI = 0.26–0.76).
Serious adverse events were uncommon and similar in the low-dose tamoxifen and control intervention groups.
The investigators concluded: “Low-dose tamoxifen was associated with a sustained reduction in breast cancer events, with differences by menopausal status and site of event. These findings support endocrine dose de-escalation to improve the benefit-risk profile of preventive therapy in DCIS and high-risk lesions.”
Andrea DeCensi, MD, of Medical Oncology Unit, EO Ospedali Galliera, Genoa, Italy, is the corresponding author for the Journal of Clinical Oncology article.
DISCLOSURE: The study was supported by the Italian Ministry of Health and others. For full disclosures of the study authors, visit ascopubs.org.
