We herein present the case of a 30-year-old Japanese male patient with ulcerative colitis (UC) who was admitted to our hospital because of significant ascites. Upon evaluation, the patient was diagnosed with unresectable UC-associated colon cancer (UCAC), localized in the transverse colon. Using gene profiling of the tumor tissue, anti-epidermal growth factor receptor (EGFR) antibody combination chemotherapy was selected. Subsequently, the patient exhibited a temporary response to this regimen, with an enhancement in his quality of life and he was able to survive for 12 months. This case underscores the potential benefits of aggressive chemotherapy tailored to the gene profile in UCAC treatment, offering insights into potential avenues for improving the patient prognosis.