Colonic Metastasis in a Patient With Hereditary Diffuse Gastric Cancer: A Case Report.

Metastasis of gastric carcinoma to atypical locations can complicate management, often leading clinicians to rely heavily on chemotherapy. While instances of gastric carcinoma spreading to the liver, peritoneum, and lymphatics are well documented in the literature, there is limited evidence of its spread to intraintestinal organs, particularly the colon. This scarcity of reports complicates diagnosis, given the variations in histopathology. This case report highlights a 35-year-old patient diagnosed with colonic metastasis from hereditary diffuse gastric cancer (HDGC) while being evaluated for potential causes of iron deficiency anemia. A mutation in the E-cadherin (CDH1) tumor suppressor gene is associated with HDGC. Dysregulation of CDH1 leads to tumor proliferation, invasion, migration, and metastasis. Treatment options for gastric cancer include surgical resection with neoadjuvant or adjuvant chemotherapy or palliative care with chemotherapy in metastatic disease. Although colonic metastasis from gastric cancer is rare, documented incidents can offer valuable insights that avoid misdiagnosing primary tumors and help guide further management.