With the widespread application of colorectal cancer screening, the surveillance and management of the increasing number of screened population has become a pivotal aspect in preventing and controlling colorectal cancer. In recent years, researches have been conducted on the risk of colorectal cancer incidence and mortality in the population after screening. At the same time, various organizations in Europe and the United States have continuously updated colonoscopy surveillance after screening and polypectomy based on the latest research evidence. In this review, we summarized the current progress of studies on colorectal cancer risk in post-screening colorectal cancer populations and the key points of relevant guideline updates, in order to provide a reference for conducting relevant studies and formulating surveillance guidelines or consensus in China.

With the widespread application of colorectal cancer screening, the surveillance and management of the increasing number of screened population has become a pivotal aspect in preventing and controlling colorectal cancer. In recent years, researches have been conducted on the risk of colorectal cancer incidence and mortality in the population after screening. At the same time, various organizations in Europe and the United States have continuously updated colonoscopy surveillance after screening and polypectomy based on the latest research evidence. In this review, we summarized the current progress of studies on colorectal cancer risk in post-screening colorectal cancer populations and the key points of relevant guideline updates, in order to provide a reference for conducting relevant studies and formulating surveillance guidelines or consensus in China.

Objective:The incidence of early-onset colorectal cancer (EOCRC) is increasing globally; however, the molecular characteristics and prognosis of sporadic EOCRC are unclear. In this systematic review and meta-analysis, we aimed to investigate the incidence of gene mutations and their association with cancer survival in sporadic EOCRC, focusing on six common gene mutations ( TP53, BRAF, KRAS, NRAS, PTEN, and APC). Methods:Ovid Embase and Ovid Medline electronic databases were searched for studies involving patients with sporadic EOCRC (i.e., diagnosed with colorectal cancer before the age of 50 years and with no evidence of hereditary syndromes predisposing to colorectal cancer). The included articles were evaluated using quality assessment tools. Meta-analysis was performed using random-effects and fixed-effects models. Cochran's Q statistic and the I2 index were used to assess heterogeneity. The incidence of the six common gene mutations listed above in sporadic EOCRC and their association with cancer survival were evaluated.Results:(1) Incidence of specific gene mutations in sporadic EOCRC. A total of 34 articles were included in this meta-analysis. The incidence of APC gene mutation was 36% (from 13 articles, 95%CI: 19%-55%, P=0.043); of KRAS gene mutation 30% (from 26 articles, 95%CI: 24%-35%, P=0.190); of BRAF gene mutation 7% (from 18 articles, 95%CI: 5%-11%, P=0.422); of NRAS gene mutation 4% (from five articles, 95%CI: 3%-5%, P=0.586); of PTEN gene mutation 6% (from six articles, 95%CI: 4%-10%, P=0.968); and of TP53 gene mutation 59% (from 13 articles, 95%CI: 49%-68%, P=0.164). (2) Association between gene mutations and survival in sporadic EOCRC . A total of six articles were included in this meta-analysis. Compared with wild-type BRAF, mutant BRAF was significantly associated with increased overall mortality risk in patients with EOCRC (pooled HR=2.85, 95%CI: 1.45-5.60, P=0.002). Subgroup analysis showed that the incidence of BRAF gene mutation was higher in Eastern than in Western countries, whereas the incidence of TP53, KRAS, NRAS, and APC gene mutations was lower. There was no significant difference in the incidence of PTEN gene mutation between different regions. Conclusion:Compared with colorectal cancer occurring in the general population, the incidence of APC and KRAS mutations is lower in EOCRC, whereas the incidence of TP53 mutation remains consistent. BRAF mutation is associated with increased overall mortality risk in patients with EOCRC.

Objective:The incidence of early-onset colorectal cancer (EOCRC) is increasing globally; however, the molecular characteristics and prognosis of sporadic EOCRC are unclear. In this systematic review and meta-analysis, we aimed to investigate the incidence of gene mutations and their association with cancer survival in sporadic EOCRC, focusing on six common gene mutations ( TP53, BRAF, KRAS, NRAS, PTEN, and APC). Methods:Ovid Embase and Ovid Medline electronic databases were searched for studies involving patients with sporadic EOCRC (i.e., diagnosed with colorectal cancer before the age of 50 years and with no evidence of hereditary syndromes predisposing to colorectal cancer). The included articles were evaluated using quality assessment tools. Meta-analysis was performed using random-effects and fixed-effects models. Cochran's Q statistic and the I2 index were used to assess heterogeneity. The incidence of the six common gene mutations listed above in sporadic EOCRC and their association with cancer survival were evaluated.Results:(1) Incidence of specific gene mutations in sporadic EOCRC. A total of 34 articles were included in this meta-analysis. The incidence of APC gene mutation was 36% (from 13 articles, 95%CI: 19%-55%, P=0.043); of KRAS gene mutation 30% (from 26 articles, 95%CI: 24%-35%, P=0.190); of BRAF gene mutation 7% (from 18 articles, 95%CI: 5%-11%, P=0.422); of NRAS gene mutation 4% (from five articles, 95%CI: 3%-5%, P=0.586); of PTEN gene mutation 6% (from six articles, 95%CI: 4%-10%, P=0.968); and of TP53 gene mutation 59% (from 13 articles, 95%CI: 49%-68%, P=0.164). (2) Association between gene mutations and survival in sporadic EOCRC . A total of six articles were included in this meta-analysis. Compared with wild-type BRAF, mutant BRAF was significantly associated with increased overall mortality risk in patients with EOCRC (pooled HR=2.85, 95%CI: 1.45-5.60, P=0.002). Subgroup analysis showed that the incidence of BRAF gene mutation was higher in Eastern than in Western countries, whereas the incidence of TP53, KRAS, NRAS, and APC gene mutations was lower. There was no significant difference in the incidence of PTEN gene mutation between different regions. Conclusion:Compared with colorectal cancer occurring in the general population, the incidence of APC and KRAS mutations is lower in EOCRC, whereas the incidence of TP53 mutation remains consistent. BRAF mutation is associated with increased overall mortality risk in patients with EOCRC.

Objective:To explore the differences in distribution of colorectal cancer-related risk factors between patients with early-onset colorectal cancer (EOCRC) and those with late-onset colorectal cancer (LOCRC) in a Chinese cohort, and to provide reference and guidance for the prevention, diagnosis, and treatment of EOCRC.Methods:Using data from the National Colorectal Cancer Cohort study cohort, 5377 patients with newly diagnosed colorectal cancer (CRC) attending the Department of Colorectal Surgery and Oncology of the Second Affiliated Hospital, Zhejiang University School of Medicine from June 2018 to February 2023 were included in the study cohort. Questionnaires capturing epidemiological features, including lifestyle and dietary habits, were administered. The patients were divided into two groups, the cut-off age being 50 years. Those aged ≥50 years were defined as having LOCRC and those aged <50 years as having EOCRC. Wilcoxon (continuous variates) or χ 2 tests (categorical variates) were performed to compare differences in epidemiological features. Results:A total of 3799 people who had completed the questionnaire were included in this study, 491 of whom had EOCRC and 3308 LOCRC. The response rate to the questionnaire was 70.7%. The median ages of patients in the EOCRC and LOCRC groups were 43 and 66 years, respectively. There was a higher proportion of female patients (48.5% [253/491] vs. 35.8% [1184/3308], χ 2=28.8, P<0.001) in the EOCRC than the LOCRC group. Patients with EOCRC and lower body mass index (medium 22.1 kg/m 2 vs. 22.9 kg/m 2, W=744 793, P=0.005) and lower proportion of abdominal obesity (87.2% [428/491] vs. 93.8% [3103/3308], χ 2=38.3, P<0.001). Patients with EORC significantly less commonly reported a history of hypertension (5.9% [29/491] vs. 41.6% [1375/3308], χ 2=231.8, P<0.001), diabetes (1.4% [7/491] vs. 14.4% [476/3308], χ 2=63.6, P<0.001) and cardiovascular and cerebrovascular diseases (0.8% [4/491] vs. 7.3% [241/3308], χ 2=28.6, P<0.001). However, the proportion of patients with a family history of CRC was significantly higher ( P<0.05) in the EOCRC group (10.2% [50/491] vs. 6.9% [227/3 308], χ 2=6.5, P=0.010]. In terms of lifestyle, patients with EOCRC had shorter sleep duration (median: 8.0 hours vs. 8.5 hours, W=578 989, P<0.001), and were less likely to participate in physical exercise (29.5% [145/491] vs. 38.7% [1281/3308] χ 2=15.0, P<0.001) or engage in physical work (65.2% [320/491] vs. 74.1% [2450/3308], χ 2=16.7, P<0.001). Meanwhile, in the EOCRC group a lower percentage of patients were smokers (29.3% [144/491] vs. 42.7% [1411/3308], χ 2=46.9, P<0.001) and they smoked less (median 17.6 pack/year vs. 30.0 pack/year,W=55 850, P<0.001). Fewer patients in the EOCRC group habitually drank alcohol (21.0% [103/491] vs. 38.0% [1257/3308], χ 2=57.5, P<0.001) or tea (17.5% [86/491] vs. 28.7% [948/3308], χ 2=26.2, P<0.001) than in the LOCRC group. Compared with the LOCRC group, patients with EOCRC had a higher frequency of intake of fresh meat, fresh fruit, eggs, and dairy products and a lower frequency of intake of preserved meat and pickled vegetables; these differences are statistically significant (all P<0.05). There was no statistically significant difference in consumption of fresh vegetables or a high-sugar diet between the two groups (both P>0.05). Conclusions:This study highlights disparities in adverse lifestyle and dietary habits between patients in China with EOCRC versus LOCRC.

Objective:To explore the differences in distribution of colorectal cancer-related risk factors between patients with early-onset colorectal cancer (EOCRC) and those with late-onset colorectal cancer (LOCRC) in a Chinese cohort, and to provide reference and guidance for the prevention, diagnosis, and treatment of EOCRC.Methods:Using data from the National Colorectal Cancer Cohort study cohort, 5377 patients with newly diagnosed colorectal cancer (CRC) attending the Department of Colorectal Surgery and Oncology of the Second Affiliated Hospital, Zhejiang University School of Medicine from June 2018 to February 2023 were included in the study cohort. Questionnaires capturing epidemiological features, including lifestyle and dietary habits, were administered. The patients were divided into two groups, the cut-off age being 50 years. Those aged ≥50 years were defined as having LOCRC and those aged <50 years as having EOCRC. Wilcoxon (continuous variates) or χ 2 tests (categorical variates) were performed to compare differences in epidemiological features. Results:A total of 3799 people who had completed the questionnaire were included in this study, 491 of whom had EOCRC and 3308 LOCRC. The response rate to the questionnaire was 70.7%. The median ages of patients in the EOCRC and LOCRC groups were 43 and 66 years, respectively. There was a higher proportion of female patients (48.5% [253/491] vs. 35.8% [1184/3308], χ 2=28.8, P<0.001) in the EOCRC than the LOCRC group. Patients with EOCRC and lower body mass index (medium 22.1 kg/m 2 vs. 22.9 kg/m 2, W=744 793, P=0.005) and lower proportion of abdominal obesity (87.2% [428/491] vs. 93.8% [3103/3308], χ 2=38.3, P<0.001). Patients with EORC significantly less commonly reported a history of hypertension (5.9% [29/491] vs. 41.6% [1375/3308], χ 2=231.8, P<0.001), diabetes (1.4% [7/491] vs. 14.4% [476/3308], χ 2=63.6, P<0.001) and cardiovascular and cerebrovascular diseases (0.8% [4/491] vs. 7.3% [241/3308], χ 2=28.6, P<0.001). However, the proportion of patients with a family history of CRC was significantly higher ( P<0.05) in the EOCRC group (10.2% [50/491] vs. 6.9% [227/3 308], χ 2=6.5, P=0.010]. In terms of lifestyle, patients with EOCRC had shorter sleep duration (median: 8.0 hours vs. 8.5 hours, W=578 989, P<0.001), and were less likely to participate in physical exercise (29.5% [145/491] vs. 38.7% [1281/3308] χ 2=15.0, P<0.001) or engage in physical work (65.2% [320/491] vs. 74.1% [2450/3308], χ 2=16.7, P<0.001). Meanwhile, in the EOCRC group a lower percentage of patients were smokers (29.3% [144/491] vs. 42.7% [1411/3308], χ 2=46.9, P<0.001) and they smoked less (median 17.6 pack/year vs. 30.0 pack/year,W=55 850, P<0.001). Fewer patients in the EOCRC group habitually drank alcohol (21.0% [103/491] vs. 38.0% [1257/3308], χ 2=57.5, P<0.001) or tea (17.5% [86/491] vs. 28.7% [948/3308], χ 2=26.2, P<0.001) than in the LOCRC group. Compared with the LOCRC group, patients with EOCRC had a higher frequency of intake of fresh meat, fresh fruit, eggs, and dairy products and a lower frequency of intake of preserved meat and pickled vegetables; these differences are statistically significant (all P<0.05). There was no statistically significant difference in consumption of fresh vegetables or a high-sugar diet between the two groups (both P>0.05). Conclusions:This study highlights disparities in adverse lifestyle and dietary habits between patients in China with EOCRC versus LOCRC.