After completing this course, the reader will be able to:1. Discuss the role of radiation therapy in the adjuvant treatment of DCIS.2. Describe the impact of tamoxifen in the treatment of DCIS.3. Discuss evolving strategies in neoadjuvant treatment for DCIS.Access and take the CME test online and receive 1 AMA PRA Category 1 Credit ™ at CME.TheOncologist.com CME CME ABSTRACTDuctal carcinoma in situ (DCIS) is the fastest growing subtype of breast cancer, mainly because of the aging of our populations and improvements in diagnostic mammography and core biopsy. DCIS represents a proliferation of malignant-appearing cells that have not invaded beyond the ductal basement membrane and is a precursor for the development of invasive breast cancer (IBC). Approximately 40% of patients with DCIS treated with biopsy alone, without complete excision or further therapy, develop IBC. Most DCIS itself is harmless if it is detected and excised before it can progress to IBC, and the current approach to DCIS treatment is aimed at just that goal. Typically, it consists of multimodal treatment including segmental mastectomy followed by radiation therapy to the whole breast and then hormonal therapy or total mastectomy followed by hormonal therapy.This review discusses the state-of-the-art in DCIS detection and treatment and highlights promising new strategies in the care of DCIS patients. The data regarding the effectiveness of breast-conserving surgery versus total mastectomy, the possible avoidance of radiation therapy in some subgroups of patients, and the role of hormonal agents are reviewed. Neoadjuvant therapy and the use of trastuzumab for DCIS are currently under investigation and may be future treatment options for DCIS. The Oncologist