This study aims to comprehensively identify the various treatment patterns of second- or subsequent-line palliative chemotherapy used in patients with metastatic colorectal cancer who have experienced failure of first-line palliative chemotherapy and to evaluate the prognosis of each treatment.

Inclusion Criteria:

• Patients who have signed the informed consent after receiving information about the purpose and method of this study.
• Patients with histologically and radiologically confirmed metastatic colorectal cancer (colorectal cancer) who have evaluable (measurable) lesions.
• Patients scheduled to receive their first second-line palliative chemotherapy following failure of first-line palliative chemotherapy (including those who relapse during or within 6 months after completion of postoperative adjuvant therapy, necessitating palliative chemotherapy).
• Patients who understand the research, are cooperative in the research process, and are deemed capable of participating until the completion date.

Exclusion Criteria:

• Female patients who are pregnant, have childbearing potential, or are breastfeeding.
• Has received an investigational product within 4 weeks from the study enrollment or has plans to participate in another clinical trial during the participation of this study.
• Other subjects who are considered inappropriate to participate in this study by the judgment of the investigator.

Patients with metastatic colorectal cancer (colon and rectal cancer) who have failed first-line palliative chemotherapy