Danielle Fishel was diagnosed with an early form of breast cancer known as ductal carcinoma in situ (DCIS), which is a stage 0 breast cancer. More specifically, she had a "high-grade DCIS with micro-invasion," meaning the cancer was technically invasive to a small degree but caught very early. She underwent surgery and radiation therapy and is now on Tamoxifen to reduce the risk of recurrence. Fishel has emphasized the importance of routine mammograms for early detection, which was key to catching her cancer at this early stage.