**DCIS: RECAST Trial** This study is for people with DCIS, which is a very early stage of breast cancer. The goal is to see if monitoring the cancer with regular check-ups (active surveillance) and using hormone therapy can work just as well as surgery. Normally, surgery is done to remove DCIS, but the trial wants to see if watching and using medicine can be a good option. If you join, you might take a study medicine or a regular hormone therapy. You’ll have MRI scans at 3 and 6 months. If the scans show you’re doing well, you can choose to keep going with the treatment. If not, surgery might be recommended. You’ll also give blood and saliva samples for tests, and part of any tissue removed during surgery will be used for research. **Key Points:** - The study lasts up to 10 years with annual follow-ups. - Regular evaluations with MRI and mammograms to check progress. - Participation includes providing blood, saliva, and tissue samples for research.