Abstract: The coexistence of autoimmune gastritis (AIG) with colon cancer is exceeding uncommom in clinical settings.This article presents a case involving an older patient with autoimmune gastritis complicated by colon cancer, who concurrently exhibited vitamin B12 deficiency,iron-deficiency anemia, malnutrition, and frailty. A favorable therapeutic result was attained through a comprehensive intervention by a geriatric interdisciplinary team. By elucidating the diagnostic and therapeutic procedures employed in this case, we aim to deepen clinicians' comprehension of the integrated management strategies for rare diseases accompanied by complex comorbidities in elderly patients.