What changes, if any, would you make to a patient’s endocrine therapy for a patient with DCIS on tamoxifen for risk reduction who develops a new lesion (LCIS) while on tamoxifen?  

 Assuming post menopausal I would switch to anastrozole.  There are published data on anastrozole for chemoprevention. Although no head to head comparison with tamoxifen A.I.'s superior in every other breast cancer scenario.  (second and first line metastatic and adjuvant) Thus nothin...

It is not an easy answer. I am guessing the clinical scenario that you have in mind is that patients still have breast tissue. The best is always to perform a total mastectomy so that you can make an argument of no need for any endocrine therapy. Also, the question is whether this recurrence is in t...