Gastric metastasis from hormone receptor-positive breast cancer ten years after radical mastectomy: a case report and literature review.

Breast cancer is the most common malignancy among women, whereas gastrointestinal metastasis is uncommon and gastric involvement is particularly rare. We report a 59-year-old woman who presented with epigastric discomfort and dysphagia 10 years after surgery and postoperative chemotherapy for right breast cancer. Gastroscopy and histopathological examination with immunohistochemistry confirmed hormone receptor-positive, HER2-negative metastatic breast carcinoma involving the stomach, and staging evaluation also revealed multiple bone metastases. Because the clinical manifestations closely mimicked primary gastric cancer, the diagnosis was challenging and required careful clinicopathological correlation. This case highlights the importance of considering late gastrointestinal metastasis in long-term breast cancer survivors and underscores the critical role of endoscopic biopsy, immunohistochemistry, and multidisciplinary evaluation in establishing an accurate diagnosis. Treatment with a CDK4/6 inhibitor combined with an aromatase inhibitor resulted in rapid symptom relief and short-term disease stabilization.