[Prognostic factors affecting the success of conversion chemotherapy in patients with unresectable liver metastases from initially colorectal cancer]

Objective: To investigate the factors affecting the success of conversion therapy in patients with initially unresectable colorectal cancer liver metastases (CRLM) in order to provide evidence-based medical evidence for formulating individualized treatment strategies for patients. Methods: A retrospective case-control study was used in this study. Clinical data of 232 patients with initially unresectable CRLM receiving first-line systemic treatment in Sun Yat-sen University Cancer Center from January 2013 to January 2020 were collected, including 98 patients of successful conversion and 134 patients of failed conversion as control. Conversion therapy scheme: 38 patients received FOLFOXIRI regimen chemotherapy (irinotecan, oxaliplatin, calcium folinate and fluorouracil), 152 patients received FOLFOX regimen (oxaliplatin, calcium folinate and fluorouracil), 19 patients received FOLRIRI regimen (irinotecan, calcium folinate and fluorouracil), 23 patients received systemic chemotherapy combined with fluorouridine hepatic artery infusion chemotherapy; 168 patients received targeted therapy, including 68 of bevacizumab and 100 of cetuximab. Logistics analysis was used to compare the factors affecting the success of conversion therapy. The Kaplan-Meier method was used to calculate progression-free survival (PFS), and the Log-rank test was used for survival comparison. Results: Among 232 patients, 98 patients had successful conversions and 134 patients had failed conversions with a successful conversion rate of 42.2%, meanwhile 30 patients underwent simple hepatectomy and 68 underwent hepatectomy combined with intraoperative radiofrequency ablation. After first-line chemotherapy, 111 patients (47.8%) were partial remission, 57 patients (24.6%) were stable disease, and 64 patients (27.6%) were progression disease. During the median follow-up of 18.8 (1.0-87.9) months, 148 patients were dead or with tumor progression. The median PFS time of patients with successful conversion was longer than that of patients with failed conversion (31.0 months vs. 9.9 months, P<0.001). Univariate analysis found that the bilobar distribution of liver tumors (P=0.003), elevated baseline carcinoembryonic antigen (CEA) levels (P=0.024), tumor invasion of the portal vein (P=0.001), number of metastatic tumor>8 (P<0.001), non-FOLFOXIRI (P=0.005), and no targeted therapy (P=0.038) were high risk factors for the failed conversion therapy. The results of multivariate logistics analysis indicated that the number of metastatic tumor >8 (OR=2.422, 95%CI: 1.291-4.544, P=0.006), portal vein invasion (OR=2.727, 95%CI: 1.237-4.170, P=0.008) were the independent risk factors for failed conversion therapy, while FOLFOXIRI regimen (OR=0.300, 95%CI: 0.135-0.666, P=0.003) and targeted drugs (OR=0.411, 95%CI: 0.209-0.809, P=0.010) were independent protective factors for successful conversion therapy. Conclusions: The number of metastatic tumor and portal vein invasion are key factors that affect the outcomes of conversion therapy for initially unresectable CRLM. If a patient can tolerate chemotherapy, a combination program of three-drug and targeted therapy is preferred for the active conversion therapy.