Diffuse Gastrointestinal Metastasis From Breast Cancer: A Case Report and Literature Review.

Breast cancer (BC) is one of the most common cancers with rare incidence of possible metastatic disease to the gastrointestinal (GI) tract. Early clinical suspicion is important for a timely referral to gastroenterology and for executing a treatment plan. It is difficult to distinguish primary gastric or colon cancer from metastatic disease, and the diagnosis of metastasis can only be established by pathological and immunohistochemistry analysis. We report an interesting case who had metastatic BC to cervical and axillary lymph nodes and was treated with radiation and endocrine therapy. She remained asymptomatic for years, then was found to have rising tumor markers on regular follow-up visits that led to an extensive workup that was negative for tumor recurrence. Five years after radiation therapy, she developed GI symptoms and was referred for esophagogastroduodenoscopy (EGD) and colonoscopy, revealing extensive GI metastatic disease involving the stomach to the rectum. For a patient with metastatic BC who presents with rising tumor markers or gastric symptoms, it is important to do diagnostic studies to rule out GI metastatic disease when no primary disease is identified in the workup.