Abstract: Objective To investigate the efficacy of stereotactic body radiotherapy （SBRT） combined with modified FOLFOXIRI （mFOLFOXIRI, irinotecan, oxaliplatin, leucovorin and fluorouracil） and cetuximab in the treatment of postoperative liver metastases in patients with KRAS, BRAF and NRAS gene wild-type colorectal cancer, and to evaluate treatment-related adverse reactions. Methods A total of 86 patients with postoperative liver metastases from colorectal cancer diagnosed in Shandong Daizhuang Hospital from January 2018 to January 2021 were selected, all of whom were KRAS, BRAF and NRAS gene wild-type. All patients were divided into control group and study group according to the random number table method, with 43 cases in each group. The patients in the control group were treated with mFOLFOXIRI and cetuximab, 14 days a cycle, for a total of 12 cycles. The patients in the study group were treated with SBRT for liver metastases on the basis of the control group. Two patients in the control group were withdrawn from the study due to intolerance of myelosuppression （grade 4）, and patients in the study group were withdrawn from the study due to intolerance of 1 case of myelosuppression, 1 case of gastrointestinal reaction and 1 case of abnormal liver function （all grade 4）. The efficacy, median progression-free survival （PFS）, median overall survival （OS） and adverse reactions were compared between the two groups after treatment. Results After 12 cycles of treatment, the objective response rate （ORR） and disease control rate （DCR） of the study group were 55.00% （22/40） and 80.00% （32/40） respectively, which were higher than 31.71% （13/41） and 58.54% （24/41） of the control group, with statistically significant differences （χ²=4.48, P=0.034; χ²=4.37, P=0.037）. After treatment, 14 patients （35.00%） in the study group were resectable, which was higher than 6 patients （14.63%） in the control group, with a statistically significant difference （χ²=4.52, P=0.034）. The median PFS and median OS of the study group were 9.2 months and 19.5 months respectively, which were longer than 6.5 months and 15.2 months of the control group, with statistically significant differences （χ²=8.83, P=0.015; χ²=7.52, P=0.027）. There were no significant differences in incidences of leukopenia [55.00% （22/40） vs. 46.34% （19/41）, χ²=0.61, P=0.436], anemia [45.00% （18/40） vs. 39.02% （16/41）, χ²=0.30, P=0.585], thrombocytopenia [37.50% （15/40） vs. 31.71% （13/41）, χ²=0.30, P=0.584], nausea and vomiting [55.00% （22/40） vs. 48.78% （20/41）, χ²=0.31, P=0.575], constipation and diarrhea [20.00% （8/40） vs. 17.07% （7/41）, χ²=0.12, P=0.734], liver function damage [35.00% （14/40） vs. 29.27% （12/41）, χ²=0.31, P=0.581], peripheral sensory neuropathy [30.00% （12/40） vs. 26.83% （11/41） ）, χ²=0.10, P=0.752], acute cholinergic syndrome [12.50% （5/40） vs. 14.63% （6/41）, χ²=0.08, P=0.779] and fatigue [52.50% （21/40） vs. 43.90% （18/41）, χ²=0.60, P=0.439]. Conclusion SBRT combined with mFOLFOXIRI and cetuximab is more effective than drug therapy alone in patients with liver metastases after colorectal cancer surgery, which can effectively prolong the survival period, and the adverse reactions are tolerable.

Key words: Colorectal neoplasms, Cetuximab, Liver metastases, Stereotactic radiotherapy, Modified FOLFOXIRI