SABCS 2022: 10-Year Update on Role of Low-Dose Tamoxifen in Noninvasive Breast Cancer

By: Julia Fiederlein Cipriano
Posted: Wednesday, December 7, 2022

According to Andrea De Censi, MD, of E.O. Ospedali Galliera, Genoa, Italy, and colleagues, at a median follow-up of 5.1 years, the recurrence rate of invasive breast cancer or ductal carcinoma in situ decreased by 52% in patients with excised noninvasive breast cancer who received low-dose tamoxifen for 3 years. The 10-year updated results of this multicenter phase III trial were presented during the 2022 San Antonio Breast Cancer Symposium (SABCS; Abstract GS4-08).

“Our findings indicate that low-dose tamoxifen given for 3 years still significantly prevents recurrences from noninvasive breast cancer after a median of 6 years from treatment cessation,” the investigators commented. “[These data provide] a valid prevention/interception option in this disease group.”

A total of 500 patients with ductal carcinoma in situ (69%), atypical ductal hyperplasia (20%), and lobular carcinoma in situ (11%) who underwent surgical excision were randomly assigned to receive 5 mg of tamoxifen daily or a placebo for 3 years. Those with high-grade or comedo/necrotic ductal carcinoma in situ were administered 25 fractions of 50 Gy of adjuvant radiotherapy. After a median follow-up of 9.1 years, neoplastic events were reported in 22 of the patients treated with tamoxifen and in 37 of those who received the placebo (hazard ratio = 0.56; P = .03); this resulted in a 5-year number needed to treat of 18. A total of 71% of the recurrences were invasive breast cancer.

“The follow-up was updated with the most recent visit within 12 months in two-thirds of the participants, so an update of all participants will be performed by September 30 with full analysis of neoplastic events, annual risk rate ratio, serious adverse events, and deaths,” the investigators explained. “Moreover, an updated analysis of potential effect modifiers will be conducted, including menopausal status, baseline estradiol levels, menopausal symptoms, body mass index, smoking status, and Ki67 of the primary lesion.”

Disclosures: The study authors reported no conflicts of interest.

2022 San Antonio Breast Cancer Symposium

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