Presurgical Oral Tamoxifen vs Transdermal 4-Hydroxytamoxifen in Women With Ductal Carcinoma In Situ: A Randomized Clinical Trial.

Importance: Oral tamoxifen citrate benefits women with ductal carcinoma in situ (DCIS), but concern about toxic effects has limited acceptance. Previous pilot studies have suggested transdermal 4-hydroxytamoxifen gel has equivalent antiproliferative efficacy to oral tamoxifen, with low systemic exposure.

Objective: To demonstrate that 4-hydroxytamoxifen gel applied to the breast skin is noninferior to oral tamoxifen in its antiproliferative effect in DCIS lesions.