Adjuvant Tamoxifen Therapy for ER-Positive DCIS

Primary Selection Criteria

The American College of Surgeons and the National Comprehensive Cancer Network recommend ER testing for all DCIS cases to guide tamoxifen decision-making 1.
Tamoxifen should only be offered to patients with ER-positive DCIS, as those with ER-negative disease derive no benefit and may experience harm 1, 2, 3.

The National Comprehensive Cancer Network recommends tamoxifen for ER-positive DCIS after breast-conserving surgery with radiation, with a Category 1 recommendation 2, 3.
Tamoxifen may be considered for ER-positive DCIS after excision alone, with a Category 2A recommendation 2, 3.
Tamoxifen may be considered to decrease contralateral breast cancer risk in women with ER-positive DCIS who have undergone mastectomy, with a Category 2B recommendation 2, 3, 5.

Tamoxifen reduces ipsilateral invasive breast cancer at 5 years from 4.2% to 2.1% 2.
Tamoxifen reduces contralateral breast cancer from 2.3% to 1.8% at 5 years 2.

The National Comprehensive Cancer Network and the American College of Surgeons recommend against offering tamoxifen to patients with ER-negative DCIS, as no benefit has been demonstrated in ER-negative disease 1, 2, 3.
ER determination is mandatory, preferably by immunohistochemistry, and reports should include the percentage of ER-positive cells 1.