Would you give adjuvant anti-hormonal therapy after bilateral mastectomies for multifocal/multicentric high grade DCIS?  

No. Since DCIS does not metastasize, the purpose of endocrine therapy, with either tamoxifen or and AI after DCIS, is to decrease the risk of local recurrence and new breast cancers. Having bilateral mastectomy decreases the risk by >90%, such that the additional benefit of preventive endocrine t...