Hello and welcome to the forum. Thank you for your question. Are you working with your doctor and this is results of a recent test? Hopefully your doctor is proactive in discussions with you regarding what the terminology means. Always ask if they are not as it is their duty to leave you with no questions unanswered about important matters like this.
DCIS stands for Ductal Carcinoma In Situ. This is a type of breast cancer that is very common and involves an abnormal growth of cells inside the breast ducts that have not invaded outside that area. It's important to diagnose and treat because it can change and become invasive cancer if not. DCIS is considered the earliest stage of beast cancer and when caught at this stage, is well treated with success. It is not considered an emergency but is best to treat as soon as you can. Here is information on DCIS https://www.mayoclinic.org/diseases-conditions/dcis/symptoms-causes/syc-20371889
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