Danielle Fishel was diagnosed with an early form of breast cancer known as ductal carcinoma in situ (DCIS), which is technically stage 0 breast cancer. Her specific diagnosis was "high-grade DCIS with micro-invasion," meaning the cancer was mostly contained within the milk ducts but had begun to show very small areas of invasion outside the ducts, which can sometimes be classified as stage 1. She underwent a lumpectomy surgery to remove the cancer and completed radiation treatment. After treatment, she is expected to start taking Tamoxifen to reduce the risk of recurrence. Fishel has emphasized that her cancer was caught very early through routine screening and encourages women to keep up with mammograms for early detection.