Third-line treatment patterns and clinical outcomes for metastatic colorectal cancer: a retrospective real-world study

Background:There are multiple recommendations on the third-line therapy of metastatic colorectal cancer (mCRC); however, no consensus has been reached.Objectives:This study aimed to explore the patient demographics and the real-world third-line treatment landscape of mCRC.Design:A retrospective real-world cohort study.Methods:Electronic medical records of mCRC patients from Tianjin Medical University Cancer Institute and Hospital between 2013 and 2020 were collected. Upon descriptive, comparative, and survival analyses, a retrospective study was conducted to describe demographics and clinical outcomes of mCRC patients receiving third-line treatment.Results:Among 218 mCRC patients receiving third-line therapy, 65.5% received chemotherapy combined with or without targeted drugs, followed by anti-angiogenic monotherapy (18.4%), anti-epidermal growth factor receptor drugs (6.9%) and immunotherapy (6.4%). The overall response rate and disease control rate reached 10.2% and 59.2%, respectively; and median progression-free survival (PFS) and overall survival were 4.0 m and 10.7 m, respectively. After Cox multivariate analysis, we found that therapeutic regime was an independent prognostic factor. Compared to patients receiving anti-angiogenic monotherapy, those receiving chemotherapy combined with or without targeted drugs exhibited better prognosis. For patients whose PFS were longer in the front-line treatment, the PFS of third-line therapy was also relatively longer (p = 0.023). Multiple types of therapies (>3, p = 0.002) or multiple drugs (>5, p = 0.024) in the whole-course management of mCRC are indicators of longer survival.Conclusion:Chemotherapy combined with or without targeted therapy remained dominated third-line choice and showed favorable efficacy compared with anti-angiogenic monotherapy. With the application of more types and quantities of effective drugs, patients would achieve better survival.