Tumour response following preoperative chemotherapy is affected by body mass index in patients with colorectal liver metastases

BACKGROUND Colorectal cancer is the third most prevalent malignancy globally and ranks second in cancer-related mortality,with the liver being the primary organ of metastasis.Preoperative chemotherapy is widely recommended for initially or potentially resectable colorectal liver metastases(CRLMs).Tumour pathological response serves as the most important and intuitive indicator for assessing the efficacy of chemotherapy.However,the postoperative pathological results reveal that a considerable number of patients exhibit a poor response to preoperative chemotherapy.Body mass index(BMI)is one of the factors affecting the tumori-genesis and progression of colorectal cancer as well as prognosis after various antitumour therapies.Several studies have indicated that overweight and obese patients with metastatic colorectal cancer experience worse prognoses than those with normal weight,particularly when receiving first-line chemotherapy regimens in combination with bevacizumab.AIM To explore the predictive value of BMI regarding the pathologic response following preoperative chemotherapy for CRLMs.METHODS A retrospective analysis was performed in 126 consecutive patients with CRLM who underwent hepatectomy following preoperative chemotherapy at four different hospitals from October 2019 to July 2023.Univariate and multivariate logistic regression models were applied to analyse potential predictors of tumour pathological response.The Kaplan-Meier method with log rank test was used to compare progression-free survival(PFS)between patients with high and low BMI.BMI<24.0 kg/m^(2) was defined as low BMI,and tumour regression grade 1-2 was defined as complete tumour response.RESULTS Low BMI was observed in 74(58.7%)patients and complete tumour response was found in 27(21.4%)patients.The rate of complete tumour response was significantly higher in patients with low BMI(29.7%vs 9.6%,P=0.007).Multivariate analysis revealed that low BMI[odds ratio(OR)=4.56,95%confidence interval(CI):1.42-14.63,P=0.011],targeted therapy with bevacizumab(OR=3.02,95%CI:1.10-8.33,P=0.033),preoperative carcinoembryonic antigen level<10 ng/mL(OR=3.84,95%CI:1.19-12.44,P=0.025)and severe sinusoidal dilatation(OR=0.17,95%CI:0.03-0.90,P=0.037)were independent predictive factors for complete tumour response.The low BMI group exhibited a significantly longer median PFS than the high BMI group(10.7 mo vs 4.7 mo,P=0.011).CONCLUSION In CRLM patients receiving preoperative chemotherapy,a low BMI may be associated with better tumour response and longer PFS.