[Effects of tumor location and mismatch repair on clinicopathological features and survival for non-metastatic colon cancer: A retrospective, single center, cohort study].

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 χ2 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%], χ2=5.462, P=0.019), body mass index (24.2 [21.9, 26.6] kg/m2 vs. 23.2 [21.3, 25.5] kg/m2, U=78,789.0, P<0.001), and well/moderately differentiated cancer (412/442 [93.2%] vs. 344/414 [83.1%], χ2=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%], χ2=34.721, P<0.001) and combined vascular invasion (106/442[24.0%] vs. 125/414[30.2%], χ2=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.

[System analysis of the ecological distribution of bacteriophages in hospital wastewater].

Phage therapy is one of the most important tools for the treatment of infections with multi-drug resistant bacteria. Such phages are usually isolated from hospital effluents, however, no systematic study on the distribution of phages in hospital effluents has been conducted so far. The aim of this study was to isolate the corresponding phages of common pathogenic bacteria isolated in the clinic as hosts, so as to assess the ecological distribution of phages in hospital wastewater and to provide a reference for the isolation and application of phages of drug-resistant bacteria in the clinic. A cross-sectional study design was used in this study. The 125 pathogenic bacteria (belonging to 16 different strains) isolated from the clinical microbiology laboratory of Qilu Hospital of Shandong University from May to June 2023 were selected as the target strains, and the phages corresponding to these strains were isolated and purified from the hospital wastewater by using the double-layer plate sandwich method. At the same time, the distribution of pathogenic bacteria in the same batch of wastewater was analyzed with the help of mNGS sequencing technology, so as to preliminarily investigate the abundance correspondence between pathogenic bacteria and phages in wastewater. The results showed that a total of 56 phage strains were isolated from 125 clinical pathogens as hosts, corresponding to six pathogens, including Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia. All six pathogenic bacteria contained strains with different degrees of drug resistance, with a higher percentage of multi-drug resistant strains in A. baumannii, Escherichia coli and P. aeruginosa. The phage acquisition rates of these six pathogens were, in descending order, Escherichia coli (80%), Stenotrophomonas maltophilia (75%), Pseudomonas aeruginosa (70%), Klebsiella pneumoniae (66.67%), Acinetobacter baumannii (36.36%) and Staphylococcus aureus (12.5%). Preliminary mNGS sequencing results showed that the pathogenic bacteria with higher abundance in the batch of effluent were Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli, Enterococcus faecalis, Acinetobacter baumannii, Klebsiella aerogenes, Klebsiella michiganensis and Pseudomonas aeruginosa. In conclusion, phages of most common clinical Gram-negative pathogens were isolated from hospital wastewater with high isolation rates; however, phages of Gram-positive pathogens were isolated at lower rates, and only phages corresponding to Staphylococcus aureus were isolated in this study. The corresponding mNGS sequencing results showed that the distribution of Gram-negative pathogens in sewage may had a positive correlation with the ecological distribution of phages.

[Comparison of the anorectal function before and after neoadjuvant radiotherapy in mid-low rectal cancer: a retrospective observational study from single center].

Objective: The aim of this study was to evaluate the impact of neoadjuvant radiotherapy on anorectal function of patients with mid-low rectal cancer by means of high-resolution anorectal manometry. Methods: A retrospective observational study was conducted. Information on patients with mid-low rectal cancer was collected from the prospective registry database of Rectal Cancer at Peking Union Medical College Hospital (PUMCH) from June 2020 to April 2023. Anorectal functions were detected using three-dimensional high-resolution manometry system. Logistic regression analysis was performed to identify the factors associated with the changed anorectal manometry. Results: A total of 45 patients with mid-low rectal cancer were included in the study. Thirty-two (71.1%) patients were male, 13 (28.9%) patients were female. The mean age was 60±11 years, and the mean BMI was 23.4±3.7 kg/m2. The mean distance between the lower edge of the tumor and the anal verge was 5.4±1.5 cm. The median size of the tumor was 3.4 (2.9-4.5) cm, and the median circumferential extent of the tumor was 66.0 (45.5-75.0) %. 41 (81.1%) patients were MRI T3-4 and 40 (88.9%) patients were MRI N positive. The resting pressure has a decreasing trend after neoadjuvant radiotherapy (55.3±32.0 mmHg vs. 48.0±28.5 mmHg, t=1.930, P=0.060). There was no significant change in maximum squeezing and the length of the high-pressure zone after neoadjuvant radiotherapy. All volumes describing rectal sensitivity (first sensation, desire to defecate, and maximum tolerance) were lower after neoadjuvant radiotherapy. And maximum tolerance was significantly lower (66.0 [49.0,88.0] ml vs. 52.0 [39.0,73.5] ml, Z=-2.481,P=0.013). Univariate analysis demonstrated that the downstage of N-stage was associated with the decrease in maximum tolerance (OR=6.533, 95%CI:1.254-34.051, P=0.026). Conclusion: Neoadjuvant radiotherapy damages anorectal function by decreasing the resting pressure and rectal sensory threshold of patients. The N-stage downstaging was associated with a decrease in maximum tolerance.