Factors Influencing the Duration of Maintenance Therapy in Metastatic Colorectal Cancer

Background/objectives: Metastatic colorectal cancer (mCRC) is mainly treated with 5-Fluoro-Uracil (5-FU), Oxaliplatin and Irinotecan chemotherapies and anti-Epidermal Growth Factor Receptor (EGFR) or anti-Vascular Endothelial Growth Factor (VEGF) targeted therapies. Due to chemotherapy-related toxicity, patients receive induction treatment to achieve tumour response followed by maintenance therapy with less cytotoxic molecules or a chemotherapy-free interval to reduce chemotherapy-related toxicity. In this study, the aim was to determine the patient, cancer and treatment factors that influence the duration of maintenance therapy (DMT).

Methods: We collected retrospective data on a cohort of 133 patients treated at the Centre Georges François Leclerc (CGFL) cancer centre in Dijon between March 2014 and June 2022. Patients had unresectable or potentially resectable diseases. They received first-line induction treatment with chemotherapy and/or targeted therapy and maintenance treatment, defined as the interruption of at least one chemotherapy agent.

Results: In the multivariate analysis, age (HR: 1.02, 95% CI 1.00-1.04, p = 0.031), N2 nodal status (HR: 1.78, 95% CI 1.09-2.89, p = 0.021) and the presence of peritoneal metastases (HR: 2.05, 95% CI 1.25-3.36, p = 0.004), as well as baseline carcino-embryonic antigen (CEA) level (HR: 1.10, 95% CI 1.00-1.20, p = 0.052), were significantly associated to poor DMT. Local treatment of liver metastases also significantly reduced the DMT (HR: 0.49, 95% CI 0.28-0.86, p = 0.013). In our cohort, induction triplet chemotherapy significantly increased the CEA delta (70% vs. 44%, p = 0.047) compared to doublet chemotherapy and led to a higher rate of liver surgery (40% vs. 21%, p = 0.014) and a trend for a higher rate of local treatment of metastases (62% vs. 45%, p = 0.059).

Conclusions: Duration of maintenance therapy is determined by the initial patient and colorectal cancer characteristics. However, it is significantly increased by local treatment of liver metastases. By reducing the tumour burden, a triplet induction chemotherapy regimen increases the rate of liver metastase resection.