The following article features coverage from the San Antonio Breast Cancer Symposium (SABCS) 2018 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Tamoxifen 5 mg per day for 3 years halved the risk of recurrence of breast intraepithelial neoplasia (IEN) in the TAM-01 phase III trial ( Identifier: NCT01357772). The trial results were presented at the 2018 San Antonio Breast Cancer Symposium (SABCS) in San Antonio, Texas.1

“We know very well that tamoxifen is very effective in prevention, but its toxicity, namely [in] rare cases of endometrial cancer, deep vein thrombosis, and menopausal symptoms, represent an important barrier for its [use],” said study presenter Andrea De Censi, MD, director of the medical oncology unit at the National Hospital E.O. Ospedali Galliera – S.C. Oncologia Medica in Genoa, Italy.

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In the TAM-01 trial, a total of 500 participants were enrolled between 2008 and 2015 from 14 centers in Italy and randomized to receive ether tamoxifen 5 mg per day or placebo for 3 years and then at least 2 years of follow-up. Eligible patients were women younger than 75 years of age who had IEN.

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At a median follow-up of 5.1 years, 42 primary events had occurred. 

There was a 52% reduction in the cumulative risk of developing a recurrence in the low-dose tamoxifen arm compared with placebo (hazard ratio [HR] = 0.48; 95% confidence interval [CI], 0.26-0.92; = .024). Likewise, there was a 75% reduction in the risk of contralateral breast cancer with low-dose tamoxifen (HR = 0.24; 95% CI, 0.07 – 0.87; P= .018).

Vaginal dryness and musculoskeletal pain in the low-dose tamoxifen arm was not statistically significantly different from the placebo arm. Daily hot flash frequency was greater in the low-dose tamoxifen arm as compared with the placebo arm (= .05). 

In the low-dose tamoxifen arm, 1 case of stage 1 endometrial cancer and 1 case of deep vein thrombosis (DVT) occurred. In the placebo arm, 1 case of pulmonary embolism occurred. 

“If we compare these findings with the NSABP-P1 prevention trial with a dose of 20 mg per day, we would expect 2.7 endometrial cancers on tamoxifen and 2.4 DVT or pulmonary emboli,” Dr De Censi said.

Read more of Cancer Therapy Advisor‘s coverage of the SABCS 2018 meeting by visiting the conference page.


  1. DeCensi A, Puntoni M, Gonzaga AG, et al. A randomized placebo controlled phase III trial of low dose tamoxifen for the prevention of recurrence in women with operated hormone sensitive breast ductal or lobular carcinoma in situ. Oral presentation at: 2018 San Antonio Breast Cancer Symposium; December 4-8, 2018; San Antonio, TX. Abstract GS3-01.