Objective:To compare the impact of different treatment strategies on the survival outcomes in rectal cancer patients with poor response to neoadjuvant therapy, and to explore the survival-related influencing factors.Methods:A retrospective cohort study was conducted. Between January 2018 and November 2022, the clinical, pathological, and follow-up data of 106 rectal cancer patients who received neoadjuvant therapy and were evaluated as grade 4 or 5 based on the Magnetic Resonance Tumor Regression Grade (mrTRG) from the rectal cancer database at Peking Union Medical College Hospital were retrospectively collected. Based on the post-neoadjuvant therapy assessment, patients were classified into three groups: the chemotherapy-radiotherapy group (23 patients), the consolidation therapy group (18 patients), and the standard treatment group (65 patients). General condition, pathological findings, selection of neoadjuvant therapy, comorbidities, as well as 3-year expected DMFS and OS were observed in the three groups.Results:All 106 patients were followed up, with a median follow-up time of 28 (21, 38) months. The overall 3-year DMFS rate was 60%, and the 3-year OS rate was 74%. The 3-year DMFS in the standard treatment and consolidation therapy groups were 74% and 72%, respectively; the 3-year OS were 84%, 81%, respectively. The Log-rank test showed that there was no significant difference in the 3-year expected DMFS and OS between the standard treatment group and the consolidation therapy group (both P>0.05), but both groups had better survival outcomes than the chemotherapy-radiotherapy group (10% and 39%, respectively; all P<0.001). Multivariate Cox regression analysis indicated that the chemotherapy-radiotherapy only regimen was an independent risk factor for DMFS (HR=12.425, 95% CI: 4.436–34.594, P<0.001), and the independent risk factors for OS were chemotherapy-radiotherapy only regimen (HR=8.991, 95%CI:2.220–36.403, P=0.002) and age≥65 years (HR=3.495, 95%CI: 1.017–12.009, P=0.047). Stratified analysis showed that chemotherapy-radiotherapy only regimen was the independent risk factors for DMFS and OS in patients with extramural vascular invasion (EMVI) positive ( n=66) and mesorectal fascial invasion (MRF) positive (n=56) (all P<0.05). Whether consolidation therapy was added to the standard neoadjuvant treatment regimen was not an independent factor affecting 3-year expected DMFS or OS in rectal cancer patients with poor response to neoadjuvant therapy. Further comparisons between the standard neoadjuvant treatment and consolidation therapy groups showed no statistically significant differences in spincter-preservation rate or postoperative complication rates (both P>0.05). However, the consolidation therapy group had a longer interval between the end of radiotherapy and surgery [80.1 (50.8, 109.4) days vs. 61.8 (48.8, 74.8) days, P<0.001], and a higher incidence of chemotherapy-related adverse effects ([10/18] vs. 26.2% [17/65], P=0.018). Conclusion:In rectal cancer patients with poor response to neoadjuvant therapy and clear adverse prognostic features before surgery (locally advanced stage, MRF positive or EMVI positive), the addition of short- or long-course chemotherapy-based systemic therapy does not provide short- or long-term survival benefits. Moreover, an extended chemotherapy duration increases the incidence of chemotherapy-related adverse effects.

Objective:To investigate the completion rate of tumor evaluation at initial assessment and after neoadjuvant therapy for mid and low rectal cancer patients in the national multicenter real-world database.Methods:The prospective real-world study was conducted. The clinicopathological data of 1 074 patients who underwent surgical treatment for mid and low rectal cancer in 47 national medical institutions, including Peking Union Medical College Hospital et al, from May 12,2023 to May 11,2024 were collected. Observation indicators: (1) clinical characteristics of patients with mid and low rectal cancer; (2) initial colonoscopy and pathologic evaluation of tumors in patients with mid and low rectal cancer; (3) initial imaging evaluation of patients with mid and low rectal cancer; (4) imaging evaluation after neoadjuvant therapy for patients with mid and low rectal cancer. Measurement data with normal distribution were represented as Mean± SD, and measurement data with skewed distribution were represented as M( Q1, Q3). Count data were described as absoluter numbers and/or percentages. Results:(1) Clinical characteristics of patients with mid and low rectal cancer. Of the 1 074 patients, there were 713 males and 361 females, aged 63(56,70)years. The body mass index of 1 074 patients was 24(21,26)kg/m 2.For American Society of Anesthesiologists classification, there were 147 cases of stage Ⅰ, 641 cases of stage Ⅱ, 157 cases of stage Ⅲ, 2 cases of stage Ⅳ, and there were 127 cases missing data. (2) Initial colonoscopy and pathologic evaluation of tumors in patients with mid and low rectal cancer. Of the 1 074 patients, there were 787 cases (73.28%) undergoing complete colonoscopy, and there were only 197 cases (18.34%) undergoing immunohistochemical evaluation of all four mismatch repair proteins. (3) Initial imaging evaluation of patients with mid and low rectal cancer. Of the 1 074 patients, there were 842(78.40%) patients completing magnetic resonance imaging (MRI) or ultrasound evaluation, and there were 914(85.10%) patients completing chest, abdomen, and pelvis enhanced computed tomography (CT) evaluation. In the 149 patients completing rectal ultrasound evaluation, there were 122 cases (81.88%) comple-ting T staging evaluation, and there were 81 cases (54.36%) completing N staging evaluation. In the 808 patients completing rectal MRI evaluation, there were 708 cases (87.62%) completing T staging evaluation, and there were 590 cases (73.02%) completing N staging evaluation. (4) Imaging evalua-tion after neoadjuvant therapy for patients with mid and low rectal cancer. Of the 388 patients with neoadjuvant therapy, there were 332 patients (85.57%) completing MRI or ultrasound evaluation, and there were 327 patients (84.28%) completing chest, abdomen, and pelvis enhanced CT evalua-tion. In the 70 patients completing rectal ultrasound evaluation, there were 65 cases (92.86%) com-pleting T staging evaluation, and there were 49 cases (70.00%) completing N staging evaluation. In the 327 patients completing rectal MRI evaluation, there were 246 cases (75.23%) completing T staging, and there were 228 cases (69.72%) completing N staging evaluation. Conclusion:The com-pletion rate of tumor imaging evaluation at initial assessment and after neoadjuvant therapy for mid and low rectal cancer patients on a national scale is relatively good.

Objective:To compare the prognostic impact of complete mesocolic excision (CME) versus D2 lymphadenectomy in patients with stage III right-sided colon cancer.Methods:A retrospective cohort study was conducted. Clinical data of 263 patients with stage III colon cancer undergoing right hemicolectomy in the Division of Colorectal Surgery, Department of General Surgery, Peking Union Medical College Hospital (January 1, 2016 to August 8, 2023) were included. Of the 263 patients, 152 underwent CME and 111 received D2 dissection. Propensity score matching (PSM) was employed to balance baseline characteristics between the two groups. Continuous variables were compared using the Mann-Whitney U test or Student's t-test; categorical variables were compared using the χ2 test or Fisher exact test. Survival curves were constructed using the Kaplan-Meier method, and the Log-Rank test was used to compare disease-free survival (DFS) and overall survival (OS) between groups. Cox proportional hazards models were utilized to analyze prognostic factors, with subgroup analyses performed.Results:Patients undergoing CME surgery were younger (proportion >75 years: 4.6% vs. 25.2%, P<0.001), had a lower burden of comorbidities (Charlson comorbidity index ≥ 1: 25.0% vs. 36.9%, P=0.045), The rates of open surgery and converted open surgery were lower [0.6% (1/152) vs. 4.5% (5/111) and 0.6% (1/152) vs. 2.7% (3/111), respectively; P=0.040].They also had a higher rate of receiving adjuvant therapy (92.7% vs. 76.0%, P<0.001). In terms of short-term postoperative outcomes, the CME group had a greater number of harvested lymph nodes (median: 30 vs. 25, P<0.001) and less blood loss (median: 20 ml vs. 20 ml, P=0.041). There were no significant differences between the groups in terms of the number of metastatic lymph nodes, operation time, and the incidence of postoperative complications. Survival analysis demonstrated significantly longer DFS in the CME group both before and after PSM. CME was an independent favorable prognostic factor for DFS (pre-PSM: HR=0.53, 95%CI: 0.31-0.91, P=0.022; post-PSM: HR=0.50, 95%CI: 0.26-0.97, P=0.042). No significant difference in OS was detected between the two groups across models. The subgroup analysis based on clinicopathological features revealed DFS benefits associated with CME in patients with tumor deposits (HR=0.41, 95%CI: 0.18-0.94, P=0.035), moderately-to-well-differentiated adenocarcinoma(HR=0.48, 95%CI: 0.26-0.90, P=0.023), proficient mismatch repair tumors (HR=0.55, 95%CI: 0.32-0.94, P=0.030), and pN2 stage disease (HR=0.43, 95%CI: 0.19-0.95, P=0.036). Conclusion:An extended lymph node dissection, as exemplified by CME, may confer a DFS advantage in patients with stage III right-sided colon cancer, especially those exhibiting a substantial burden of lymph node metastases.

Objective:To compare the impact of different treatment strategies on the survival outcomes in rectal cancer patients with poor response to neoadjuvant therapy, and to explore the survival-related influencing factors.Methods:A retrospective cohort study was conducted. Between January 2018 and November 2022, the clinical, pathological, and follow-up data of 106 rectal cancer patients who received neoadjuvant therapy and were evaluated as grade 4 or 5 based on the Magnetic Resonance Tumor Regression Grade (mrTRG) from the rectal cancer database at Peking Union Medical College Hospital were retrospectively collected. Based on the post-neoadjuvant therapy assessment, patients were classified into three groups: the chemotherapy-radiotherapy group (23 patients), the consolidation therapy group (18 patients), and the standard treatment group (65 patients). General condition, pathological findings, selection of neoadjuvant therapy, comorbidities, as well as 3-year expected DMFS and OS were observed in the three groups.Results:All 106 patients were followed up, with a median follow-up time of 28 (21, 38) months. The overall 3-year DMFS rate was 60%, and the 3-year OS rate was 74%. The 3-year DMFS in the standard treatment and consolidation therapy groups were 74% and 72%, respectively; the 3-year OS were 84%, 81%, respectively. The Log-rank test showed that there was no significant difference in the 3-year expected DMFS and OS between the standard treatment group and the consolidation therapy group (both P>0.05), but both groups had better survival outcomes than the chemotherapy-radiotherapy group (10% and 39%, respectively; all P<0.001). Multivariate Cox regression analysis indicated that the chemotherapy-radiotherapy only regimen was an independent risk factor for DMFS (HR=12.425, 95% CI: 4.436–34.594, P<0.001), and the independent risk factors for OS were chemotherapy-radiotherapy only regimen (HR=8.991, 95%CI:2.220–36.403, P=0.002) and age≥65 years (HR=3.495, 95%CI: 1.017–12.009, P=0.047). Stratified analysis showed that chemotherapy-radiotherapy only regimen was the independent risk factors for DMFS and OS in patients with extramural vascular invasion (EMVI) positive ( n=66) and mesorectal fascial invasion (MRF) positive (n=56) (all P<0.05). Whether consolidation therapy was added to the standard neoadjuvant treatment regimen was not an independent factor affecting 3-year expected DMFS or OS in rectal cancer patients with poor response to neoadjuvant therapy. Further comparisons between the standard neoadjuvant treatment and consolidation therapy groups showed no statistically significant differences in spincter-preservation rate or postoperative complication rates (both P>0.05). However, the consolidation therapy group had a longer interval between the end of radiotherapy and surgery [80.1 (50.8, 109.4) days vs. 61.8 (48.8, 74.8) days, P<0.001], and a higher incidence of chemotherapy-related adverse effects ([10/18] vs. 26.2% [17/65], P=0.018). Conclusion:In rectal cancer patients with poor response to neoadjuvant therapy and clear adverse prognostic features before surgery (locally advanced stage, MRF positive or EMVI positive), the addition of short- or long-course chemotherapy-based systemic therapy does not provide short- or long-term survival benefits. Moreover, an extended chemotherapy duration increases the incidence of chemotherapy-related adverse effects.

Objective:To investigate the completion rate of tumor evaluation at initial assessment and after neoadjuvant therapy for mid and low rectal cancer patients in the national multicenter real-world database.Methods:The prospective real-world study was conducted. The clinicopathological data of 1 074 patients who underwent surgical treatment for mid and low rectal cancer in 47 national medical institutions, including Peking Union Medical College Hospital et al, from May 12,2023 to May 11,2024 were collected. Observation indicators: (1) clinical characteristics of patients with mid and low rectal cancer; (2) initial colonoscopy and pathologic evaluation of tumors in patients with mid and low rectal cancer; (3) initial imaging evaluation of patients with mid and low rectal cancer; (4) imaging evaluation after neoadjuvant therapy for patients with mid and low rectal cancer. Measurement data with normal distribution were represented as Mean± SD, and measurement data with skewed distribution were represented as M( Q1, Q3). Count data were described as absoluter numbers and/or percentages. Results:(1) Clinical characteristics of patients with mid and low rectal cancer. Of the 1 074 patients, there were 713 males and 361 females, aged 63(56,70)years. The body mass index of 1 074 patients was 24(21,26)kg/m 2.For American Society of Anesthesiologists classification, there were 147 cases of stage Ⅰ, 641 cases of stage Ⅱ, 157 cases of stage Ⅲ, 2 cases of stage Ⅳ, and there were 127 cases missing data. (2) Initial colonoscopy and pathologic evaluation of tumors in patients with mid and low rectal cancer. Of the 1 074 patients, there were 787 cases (73.28%) undergoing complete colonoscopy, and there were only 197 cases (18.34%) undergoing immunohistochemical evaluation of all four mismatch repair proteins. (3) Initial imaging evaluation of patients with mid and low rectal cancer. Of the 1 074 patients, there were 842(78.40%) patients completing magnetic resonance imaging (MRI) or ultrasound evaluation, and there were 914(85.10%) patients completing chest, abdomen, and pelvis enhanced computed tomography (CT) evaluation. In the 149 patients completing rectal ultrasound evaluation, there were 122 cases (81.88%) comple-ting T staging evaluation, and there were 81 cases (54.36%) completing N staging evaluation. In the 808 patients completing rectal MRI evaluation, there were 708 cases (87.62%) completing T staging evaluation, and there were 590 cases (73.02%) completing N staging evaluation. (4) Imaging evalua-tion after neoadjuvant therapy for patients with mid and low rectal cancer. Of the 388 patients with neoadjuvant therapy, there were 332 patients (85.57%) completing MRI or ultrasound evaluation, and there were 327 patients (84.28%) completing chest, abdomen, and pelvis enhanced CT evalua-tion. In the 70 patients completing rectal ultrasound evaluation, there were 65 cases (92.86%) com-pleting T staging evaluation, and there were 49 cases (70.00%) completing N staging evaluation. In the 327 patients completing rectal MRI evaluation, there were 246 cases (75.23%) completing T staging, and there were 228 cases (69.72%) completing N staging evaluation. Conclusion:The com-pletion rate of tumor imaging evaluation at initial assessment and after neoadjuvant therapy for mid and low rectal cancer patients on a national scale is relatively good.

Objective:To compare the prognostic impact of complete mesocolic excision (CME) versus D2 lymphadenectomy in patients with stage III right-sided colon cancer.Methods:A retrospective cohort study was conducted. Clinical data of 263 patients with stage III colon cancer undergoing right hemicolectomy in the Division of Colorectal Surgery, Department of General Surgery, Peking Union Medical College Hospital (January 1, 2016 to August 8, 2023) were included. Of the 263 patients, 152 underwent CME and 111 received D2 dissection. Propensity score matching (PSM) was employed to balance baseline characteristics between the two groups. Continuous variables were compared using the Mann-Whitney U test or Student's t-test; categorical variables were compared using the χ2 test or Fisher exact test. Survival curves were constructed using the Kaplan-Meier method, and the Log-Rank test was used to compare disease-free survival (DFS) and overall survival (OS) between groups. Cox proportional hazards models were utilized to analyze prognostic factors, with subgroup analyses performed.Results:Patients undergoing CME surgery were younger (proportion >75 years: 4.6% vs. 25.2%, P<0.001), had a lower burden of comorbidities (Charlson comorbidity index ≥ 1: 25.0% vs. 36.9%, P=0.045), The rates of open surgery and converted open surgery were lower [0.6% (1/152) vs. 4.5% (5/111) and 0.6% (1/152) vs. 2.7% (3/111), respectively; P=0.040].They also had a higher rate of receiving adjuvant therapy (92.7% vs. 76.0%, P<0.001). In terms of short-term postoperative outcomes, the CME group had a greater number of harvested lymph nodes (median: 30 vs. 25, P<0.001) and less blood loss (median: 20 ml vs. 20 ml, P=0.041). There were no significant differences between the groups in terms of the number of metastatic lymph nodes, operation time, and the incidence of postoperative complications. Survival analysis demonstrated significantly longer DFS in the CME group both before and after PSM. CME was an independent favorable prognostic factor for DFS (pre-PSM: HR=0.53, 95%CI: 0.31-0.91, P=0.022; post-PSM: HR=0.50, 95%CI: 0.26-0.97, P=0.042). No significant difference in OS was detected between the two groups across models. The subgroup analysis based on clinicopathological features revealed DFS benefits associated with CME in patients with tumor deposits (HR=0.41, 95%CI: 0.18-0.94, P=0.035), moderately-to-well-differentiated adenocarcinoma(HR=0.48, 95%CI: 0.26-0.90, P=0.023), proficient mismatch repair tumors (HR=0.55, 95%CI: 0.32-0.94, P=0.030), and pN2 stage disease (HR=0.43, 95%CI: 0.19-0.95, P=0.036). Conclusion:An extended lymph node dissection, as exemplified by CME, may confer a DFS advantage in patients with stage III right-sided colon cancer, especially those exhibiting a substantial burden of lymph node metastases.

Objective:To analyze the differences in clinicopathological features of colon cancers and survival between patients with right- versus left-sided colon cancers.Methods:This was a retrospective cohort study. Information on patients with colon cancer from January 2016 to August 2020 was collected from the prospective registry database at Peking Union Medical College Hospital . Primary tumors located in the cecum, ascending colon, and proximal two‐thirds of the transverse colon were defined as right-sided colon cancers (RCCs), whereas primary tumors located in the distal third of the transverse colon, descending colon, or sigmoid colon were defined as left‐sided colon cancers (LCCs). Clinicopathological features were compared using the χ 2 test or Mann‐Whitney U test. Survival was estimated by Kaplan‐Meier curves and the log‐rank test. Factors that differed significantly between the two groups were identified by multivariate survival analyses performed with the Cox proportional hazards function. One propensity score matching was performed to eliminate the effects of confounding factors. Results:The study cohort comprised 856 patients, with TNM Stage I disease, 391 (45.7%) with Stage II, and 336 (39.3%) with Stage III, including 442 (51.6%) with LCC and 414 (48.4%) with RCC and 129 (15.1%). Defective mismatch repair (dMMR) was identified in 139 patients (16.2%). Compared with RCC, the proportion of men (274/442 [62.0%] vs. 224/414 [54.1%], χ 2=5.462, P=0.019), body mass index (24.2 [21.9, 26.6] kg/m 2 vs. 23.2 [21.3, 25.5] kg/m 2, U=78,789.0, P<0.001), and well/moderately differentiated cancer (412/442 [93.2%] vs. 344/414 [83.1%], χ 2=22.266, P<0.001) were higher in the LCC than the RCC group. In contrast, the proportion of dMMR (40/442 [9.0%] vs. 99/414 [23.9%], χ 2=34.721, P<0.001) and combined vascular invasion (106/442[24.0%] vs. 125/414[30.2%], χ 2=4.186, P=0.041) were lower in the LCC than RCC group. The median follow‐up time for all patients was 48 (range 33, 59) months. The log‐rank test revealed no significant differences in disease-free survival (DFS) ( P=0.668) or overall survival (OS) ( P=0.828) between patients with LCC versus RCC. Cox proportional hazards model showed that dMMR was significantly associated with a longer DFS (HR=0.419, 95%CI: 0.204?0.862, P=0.018), whereas a higher proportion of T3‐4 (HR=2.178, 95%CI: 1.089?4.359, P=0.028), N+ (HR=2.126, 95%CI: 1.443?3.133, P<0.001), and perineural invasion (HR=1.835, 95%CI: 1.115?3.020, P=0.017) were associated with poor DFS. Tumor location was not associated with DFS or OS (all P>0.05). Subsequent analysis showed that RCC patients with dMMR had longer DFS than did RCC patients with pMMR (HR=0.338, 95%CI: 0.146?0.786, P=0.012). However, the difference in OS between the two groups was not statistically significant (HR=0.340, 95%CI:0.103?1.119, P=0.076). After propensity score matching for independent risk factors for DFS, the log‐rank test revealed no significant differences in DFS ( P=0.343) or OS ( P=0.658) between patients with LCC versus RCC, whereas patient with dMMR had better DFS ( P=0.047) and OS ( P=0.040) than did patients with pMMR. Conclusions:Tumor location is associated with differences in clinicopathological features; however, this has no impact on survival. dMMR status is significantly associated with longer survival: this association may be stronger in RCC patients.

Objective:To analyze the differences in clinicopathological features of colon cancers and survival between patients with right- versus left-sided colon cancers.Methods:This was a retrospective cohort study. Information on patients with colon cancer from January 2016 to August 2020 was collected from the prospective registry database at Peking Union Medical College Hospital . Primary tumors located in the cecum, ascending colon, and proximal two‐thirds of the transverse colon were defined as right-sided colon cancers (RCCs), whereas primary tumors located in the distal third of the transverse colon, descending colon, or sigmoid colon were defined as left‐sided colon cancers (LCCs). Clinicopathological features were compared using the χ 2 test or Mann‐Whitney U test. Survival was estimated by Kaplan‐Meier curves and the log‐rank test. Factors that differed significantly between the two groups were identified by multivariate survival analyses performed with the Cox proportional hazards function. One propensity score matching was performed to eliminate the effects of confounding factors. Results:The study cohort comprised 856 patients, with TNM Stage I disease, 391 (45.7%) with Stage II, and 336 (39.3%) with Stage III, including 442 (51.6%) with LCC and 414 (48.4%) with RCC and 129 (15.1%). Defective mismatch repair (dMMR) was identified in 139 patients (16.2%). Compared with RCC, the proportion of men (274/442 [62.0%] vs. 224/414 [54.1%], χ 2=5.462, P=0.019), body mass index (24.2 [21.9, 26.6] kg/m 2 vs. 23.2 [21.3, 25.5] kg/m 2, U=78,789.0, P<0.001), and well/moderately differentiated cancer (412/442 [93.2%] vs. 344/414 [83.1%], χ 2=22.266, P<0.001) were higher in the LCC than the RCC group. In contrast, the proportion of dMMR (40/442 [9.0%] vs. 99/414 [23.9%], χ 2=34.721, P<0.001) and combined vascular invasion (106/442[24.0%] vs. 125/414[30.2%], χ 2=4.186, P=0.041) were lower in the LCC than RCC group. The median follow‐up time for all patients was 48 (range 33, 59) months. The log‐rank test revealed no significant differences in disease-free survival (DFS) ( P=0.668) or overall survival (OS) ( P=0.828) between patients with LCC versus RCC. Cox proportional hazards model showed that dMMR was significantly associated with a longer DFS (HR=0.419, 95%CI: 0.204?0.862, P=0.018), whereas a higher proportion of T3‐4 (HR=2.178, 95%CI: 1.089?4.359, P=0.028), N+ (HR=2.126, 95%CI: 1.443?3.133, P<0.001), and perineural invasion (HR=1.835, 95%CI: 1.115?3.020, P=0.017) were associated with poor DFS. Tumor location was not associated with DFS or OS (all P>0.05). Subsequent analysis showed that RCC patients with dMMR had longer DFS than did RCC patients with pMMR (HR=0.338, 95%CI: 0.146?0.786, P=0.012). However, the difference in OS between the two groups was not statistically significant (HR=0.340, 95%CI:0.103?1.119, P=0.076). After propensity score matching for independent risk factors for DFS, the log‐rank test revealed no significant differences in DFS ( P=0.343) or OS ( P=0.658) between patients with LCC versus RCC, whereas patient with dMMR had better DFS ( P=0.047) and OS ( P=0.040) than did patients with pMMR. Conclusions:Tumor location is associated with differences in clinicopathological features; however, this has no impact on survival. dMMR status is significantly associated with longer survival: this association may be stronger in RCC patients.

Objective:To investigate the interactive effect of mismatch repair (MMR) protein status and adverse clinicopathological features on prognosis of stage Ⅰ-Ⅲ colon cancer.Methods:The retrospective cohort study was conducted. The clinicopathological data of 1 650 patients with colon cancer of stage Ⅰ-Ⅲ who were admitted to 7 hospitals in China from January 2016 to December 2017 were collected. There were 963 males and 687 females, aged 62(53,71)years. Patients were classified as 230 cases of MMR deficiency (dMMR) and 1 420 cases of MMR proficiency (pMMR) based on their MMR protein status. Observation indicators: (1) comparison of clinicopathological characteristics between patients of different MMR protein status; (2) analysis of factors affecting the survival outcomes of patients of dMMR; (3) analysis of factors affecting the survival outcomes of patients of pMMR; (4) interaction analysis of MMR and adverse clinicopathological features on survival outcomes. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was conducted using the independent t test. Measurement data with skewed distribution were represented as M( Q1, Q3), and comparison between groups was conducted using the Mann-Whitney U test. Count data were described as absolute numbers, and comparison between groups was conducted using the chi-square test or Fisher exact probability. Comparison of ordinal data was conducted using the Mann-Whitney U test. The random forest interpolation method was used for missing values in data interpolation. Univariate analysis was conducted using the COX proportional risk regression model, and multivariate analysis was conducted using the COX stepwise regression with forward method. The coefficient of multiplication interaction effect was obtained using the interaction term coefficient of COX proportional risk regression model. Evaluation of additive interaction effects was conducted using the relative excess risk due to interaction ( RERI). Results:(1) Comparison of clinicopathological characteristics between patients of different MMR protein status. There were significant differences in age, T staging, the number of lymph node harvest, the number of lymph node harvest <12, high grade tumor between patients of dMMR and pMMR ( P<0.05). (2) Analysis of factors affecting the survival outcomes of patients of dMMR. Results of multivariate analysis showed that T staging, N staging, the number of lymph node harvest <12 were independent factors affecting the disease-free survival (DFS) of colon cancer patients of dMMR ( hazard ratio=3.548, 2.589, 6.702, 95% confidence interval as 1.460-8.620, 1.064-6.301, 1.886-23.813, P<0.05). Age and N staging were independent factors affecting the overall survival (OS) of colon cancer patients of dMMR ( hazard ratio=1.073, 10.684, 95% confidence interval as 1.021-1.126, 2.311-49.404, P<0.05). (3) Analysis of factors affecting the survival outcomes of patients of pMMR. Results of multivariate analysis showed that age, T staging, N staging, vascular tumor thrombus were independent factors affecting the DFS of colon cancer patients of pMMR ( hazard ratio=1.018, 2.214, 2.598, 1.549, 95% confidence interval as 1.006-1.030, 1.618-3.030, 1.921-3.513, 1.118-2.147, P<0.05). Age, T staging, N staging, high grade tumor were independent factors affecting the OS of colon cancer patients of pMMR ( hazard ratio=1.036, 2.080, 2.591, 1.615, 95% confidence interval as 1.020-1.052, 1.407-3.075, 1.791-3.748, 1.114-2.341, P<0.05). (4) Interaction analysis of MMR and adverse clinicopathological features on survival outcomes. Results of interaction analysis showed that the multiplication interaction effect between the number of lymph node harvest <12 and MMR protein status was significant on DFS of colon cancer patients ( hazard ratio=3.923, 95% confidence interval as 1.057-14.555, P<0.05). The additive interaction effects between age and MMR protein status, between high grade tumor and MMR protein status were significant on OS of colon cancer patients ( RERI=-0.033, -1.304, 95% confidence interval as -0.049 to -0.018, -2.462 to -0.146). Conclusions:There is an interaction between the MMR protein status and the adverse clinicopathological features (the number of lymph node harvest <12, high grade tumor) on prognosis of colon cancer patients of stage Ⅰ-Ⅲ. In patients of dMMR, the number of lymph node harvest <12 has a stronger predictive effect on poor prognosis. In patients of pMMR, the high grade tumor has a stronger predictive effect on poor prognosis.

Objective To investigate the mechanism of action of integrin α4 (ITGA4) in liver fibrosis based on the anti-liver fibrosis effect of sticky sugar amino acid (SSAA) in rats. Methods A rat model of liver fibrosis was induced by intraperitoneal injection of CCl 4 , and then colchicine and low-, middle-, and high-dose SSAA were used for intervention, with blank control group and SSAA group as control. After 12 weeks of experimental intervention, serum and liver samples were collected to measure the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and HE staining and Sirius Red staining were used to observe the pathological conditions of liver tissue; quantitative real-time PCR was used to measure the transcriptional level of ITGA4, integrin β1 (ITGB1), transforming growth factor-β1 (TGFβ1), alpha-smooth muscle actin (α-SMA), and TIMP2 in liver tissue; Western blot was used to measure the relative protein expression levels of ITGA4, ITGB1, TGFβ1, α-SMA, MMP2, TIMP1, and TIMP2; immunohistochemistry was used to observe the protein expression of TGFβ1 and α-SMA. A one-way analysis of variance was used for comparison of continuous data between multiple groups, and the least significant difference t -test was used for comparison between two groups. Results There were significant increases in AST and ALT in the CCl 4 model group, and intervention with colchicine or low-, middle-, and high-dose SSAA reduced the levels of AST and ALT, with a significant difference between the CCl 4 model group and the other groups (all P < 0.05). HE staining and Sirius Red staining showed disordered structure of hepatic lobules and an increase in collagen fibers in the CCl 4 model group, and the structure of hepatic lobules was improved after intervention with colchicine or low-, middle-, and high-dose SSAA. The CCl 4 model group had significantly higher transcriptional levels of ITGA4, TGFβ1, α-SMA, and TIMP2 than the other groups, and there were significant reductions in the transcriptional levels of each factor after intervention with colchicine or SSAA, with a significant difference between the CCl 4 model group and the other groups (all P < 0.05). The CCl 4 model group had significantly higher protein expression levels of ITGA4, TGFβ1, α-SMA, TIMP2, and TIMP1 and a significantly lower protein expression level of MMP2 than the other groups, and intervention with colchicine or SSAA inhibited the expression of ITGA4, TGFβ1, α-SMA, TIMP2, and TIMP1 and promoted the expression of MMP2. Immunohistochemistry showed that the CCl 4 model group had significantly higher expression levels of TGFβ1 and α-SMA than the other groups, which was inhibited by intervention with colchicine or SSAA. The high-dose SSAA group had the most significant effect in reducing aminotransferases, improving lobular structure, and inhibiting the protein expression of liver fibrosis factors. Conclusion The high expression of ITGA4 in the liver is associated with the development of liver fibrosis, which is consistent with the increases in the expression of TGFβ1 and α-SMA. Inhibiting the expression of ITGA4 can provide more therapeutic targets for liver fibrosis and expand the anti-liver fibrosis mechanism of SSAA.