Endocrine Therapy Initiation among Older Women with Ductal Carcinoma In Situ.

Less than half of older women with DCIS initiate endocrine therapy to prevent second breast cancers. Our findings suggest use was more common, but not exclusive, among women with ER-positive DCIS, but not among women who underwent BCS alone. Endocrine therapy should be targeted toward patients most likely to benefit from its use.