Abstract：
BACKGROUND: The beneficial role of gut microbiota and bacterial metabolites, including short-chain fatty acids (SCFAs), is well recognized, although the available literature around their role in colorectal cancer (CRC) has been inconsistent.
METHODS: We performed a systematic review and meta-analysis to examine the associations of fecal SCFA concentrations to the incidence and risk of CRC. Data extraction through Medline, Embase, and Web of Science was carried out from database conception to June 29, 2022. Predefined inclusion/exclusion criteria led to the selection of 17 case-control and six cross-sectional studies for quality assessment and analyses. Studies were categorized for CRC risk or incidence, and RevMan 5.4 was used to perform the meta-analyses. Standardized mean differences (SMD) with 95% confidence intervals (CI) were calculated using a random-effects model. Studies lacking quantitation were included in qualitative analyses.
RESULTS: Combined analysis of acetic, propionic, and butyric acid revealed significantly lower concentrations of these SCFAs in individuals with a high-risk of CRC (SMD = 2.02, 95% CI 0.31 to 3.74, P = 0.02). Additionally, CRC incidence was higher in individuals with lower levels of SCFAs (SMD = 0.45, 95% CI 0.19 to 0.72, P = 0.0009), compared to healthy individuals. Qualitative analyses identified 70.4% of studies reporting significantly lower concentrations of fecal acetic, propionic, butyric acid, or total SCFAs in those at higher risk of CRC, while 66.7% reported significantly lower concentrations of fecal acetic and butyric acid in CRC patients compared to healthy controls.
CONCLUSIONS: Overall, lower fecal concentrations of the three major SCFAs are associated with higher risk of CRC and incidence of CRC.
METHODS: We performed a systematic review and meta-analysis to examine the associations of fecal SCFA concentrations to the incidence and risk of CRC. Data extraction through Medline, Embase, and Web of Science was carried out from database conception to June 29, 2022. Predefined inclusion/exclusion criteria led to the selection of 17 case-control and six cross-sectional studies for quality assessment and analyses. Studies were categorized for CRC risk or incidence, and RevMan 5.4 was used to perform the meta-analyses. Standardized mean differences (SMD) with 95% confidence intervals (CI) were calculated using a random-effects model. Studies lacking quantitation were included in qualitative analyses.
RESULTS: Combined analysis of acetic, propionic, and butyric acid revealed significantly lower concentrations of these SCFAs in individuals with a high-risk of CRC (SMD = 2.02, 95% CI 0.31 to 3.74, P = 0.02). Additionally, CRC incidence was higher in individuals with lower levels of SCFAs (SMD = 0.45, 95% CI 0.19 to 0.72, P = 0.0009), compared to healthy individuals. Qualitative analyses identified 70.4% of studies reporting significantly lower concentrations of fecal acetic, propionic, butyric acid, or total SCFAs in those at higher risk of CRC, while 66.7% reported significantly lower concentrations of fecal acetic and butyric acid in CRC patients compared to healthy controls.
CONCLUSIONS: Overall, lower fecal concentrations of the three major SCFAs are associated with higher risk of CRC and incidence of CRC.
摘要：
背景：肠道菌群和细菌代谢产物的有益作用，包括短链脂肪酸（SCFA），是公认的，尽管关于它们在结直肠癌（CRC）中的作用的现有文献并不一致。
方法：我们进行了系统评价和荟萃分析，以检查粪便SCFA浓度与CRC发生率和风险的关系。通过Medline进行数据提取，Embase,和WebofScience是从数据库概念到2022年6月29日进行的。预定义的纳入/排除标准导致选择了17项病例对照和6项横断面研究进行质量评估和分析。研究对CRC风险或发病率进行了分类，使用RevMan5.4进行荟萃分析。使用随机效应模型计算具有95％置信区间（CI）的标准化平均差（SMD）。缺乏定量的研究包括在定性分析中。
结果：乙酸，丙酸,和丁酸显示，在CRC高危个体中，这些SCFA的浓度显着降低（SMD=2.02，95％CI0.31至3.74，P=0.02）。此外,SCFA水平较低的个体CRC发生率较高（SMD=0.45，95％CI0.19至0.72，P=0.0009），与健康个体相比。定性分析确定70.4％的研究报告粪便乙酸的浓度显着降低，丙酸,丁酸,或总SCFA在CRC风险较高的人群中，而与健康对照相比,66.7%报告CRC患者的粪便乙酸和丁酸浓度显著降低.
结论：总体而言，3种主要SCFA的粪便浓度较低与CRC风险和CRC发生率较高相关.
方法：我们进行了系统评价和荟萃分析，以检查粪便SCFA浓度与CRC发生率和风险的关系。通过Medline进行数据提取，Embase,和WebofScience是从数据库概念到2022年6月29日进行的。预定义的纳入/排除标准导致选择了17项病例对照和6项横断面研究进行质量评估和分析。研究对CRC风险或发病率进行了分类，使用RevMan5.4进行荟萃分析。使用随机效应模型计算具有95％置信区间（CI）的标准化平均差（SMD）。缺乏定量的研究包括在定性分析中。
结果：乙酸，丙酸,和丁酸显示，在CRC高危个体中，这些SCFA的浓度显着降低（SMD=2.02，95％CI0.31至3.74，P=0.02）。此外,SCFA水平较低的个体CRC发生率较高（SMD=0.45，95％CI0.19至0.72，P=0.0009），与健康个体相比。定性分析确定70.4％的研究报告粪便乙酸的浓度显着降低，丙酸,丁酸,或总SCFA在CRC风险较高的人群中，而与健康对照相比,66.7%报告CRC患者的粪便乙酸和丁酸浓度显著降低.
结论：总体而言，3种主要SCFA的粪便浓度较低与CRC风险和CRC发生率较高相关.
