Case Report: Liver Metastasis from Ductal Carcinoma In Situ of the Breast

Purpose: This article reports a rare case of liver metastasis in a patient with breast ductal carcinoma in situ (DCIS) after surgery, aiming to emphasize the rarity and potential metastatic risk of DCIS, especially liver metastasis, and provide reference for clinical diagnosis and treatment. Patients and Methods: The clinical data of a 35-year-old female patient with liver metastasis from DCIS admitted to our hospital were collected, and the latest literature and clinical guidelines were systematically reviewed. Results: The patient was diagnosed with high-grade, HER2-positive, large-volume (5.0 cm × 3.5 cm) DCIS (TisN0M0) in September 2021. Liver metastasis was confirmed 5 months after surgery. After 10 cycles of TCbHP regimen (docetaxel + carboplatin + trastuzumab + pertuzumab), liver metastases achieved complete remission. Subsequent maintenance therapy with HP combined with capecitabine maintained stable disease without recurrence. Conclusion: Distant metastasis of DCIS is extremely rare but can occur in high-risk populations. High-grade, large tumor size (>3 cm), HER2 positivity, and high Ki-67 are independent high-risk factors with moderate-to-high evidence levels. Early identification of high-risk DCIS and active anti-HER2 targeted combination therapy can significantly improve the prognosis of metastatic patients.