Anterior resection syndrome: a randomized clinical trial of a 5-HT3 receptor antagonist (ramosetron) in male patients with rectal cancer

Treatment of anterior resection syndrome: A systematic review and network meta-analysis

INTRODUCTION

There has been a lack of research comparing the efficacy of various treatments for low anterior resection syndrome (LARS).

METHODS

We conducted a comprehensive search across six electronic databases and a paired meta-analysis was undertaken to assess the effectiveness of the interventions. Furthermore, a network meta-analysis was utilized to compare the efficacy of different treatments for LARS.

RESULTS

This study encompassed nine randomized controlled trials, involving a total of 450 patients. Compared to routine care, 5-HT3 receptor antagonists (follow-up<3 months) and percutaneous tibial nerve stimulation (3 months ≤ follow-up <6 months) were effective in reducing the LARS score. Pelvic floor rehabilitation (follow-up≤3 months) was effective in decreasing daily number of bowel movements when compared to routine care. The network meta-analysis indicated that 5-HT3 receptor antagonists (follow-up<3 months) were the most effective in reducing both the LARS score and the daily number of bowel movements. Transanal irrigation (3 months ≤ follow-up ≤ 12 months) was most effective in reducing the LARS score. Additionally, 5-HT3 receptor antagonists demonstrated relative efficacy in improving patients' quality of life (follow-up ≤ 1 month).

CONCLUSIONS

This review indicates that 5-HT3 receptor antagonists and anal irrigation show significant promise in the treatment of LARS. Nevertheless, the contributions of percutaneous tibial nerve stimulation and pelvic floor rehabilitation to LARS treatment should not be overlooked. Given the clinical heterogeneity observed among the studies, the results should be interpreted with caution.

Ondansetron for Low Anterior Resection Syndrome (LARS): A Double-Blind, Placebo-Controlled, Cross-Over, Randomized Study

OBJECTIVE

The aim of the study was to examine the efficacity and safety of ondansetron, a serotonin receptor antagonist, to treat patients with low anterior resection syndrome (LARS).

BACKGROUND

LARS after rectal resection is common and debilitating. Current management strategies include behavioral and dietary modifications, physiotherapy, antidiarrheal drugs, enemas, and neuromodulation, but the results are not always satisfactory.

METHODS

This is a randomized, multicentric, double-blinded, placebo-controlled, and cross-over study. Patients with LARS (LARS score >20) no longer than 2 years after rectal resection were randomized to receive either 4 weeks of ondansetron followed by 4 weeks of placebo (O-P group) or 4 weeks of placebo followed by 4 weeks of ondansetron (P-O group). The primary endpoint was LARS severity measured using the LARS score; secondary endpoints were incontinence (Vaizey score) and irritable bowel syndrome quality of life (IBS-QoL questionnaire). Patients' scores and questionnaires were completed at baseline and after each 4-week treatment period.

RESULTS

Of 46 randomized patients, 38 were included in the analysis. From baseline to the end of the first period, in the O-P group, the mean (SD) LARS score decreased by 25% [from 36.6 (5.6) to 27.3 (11.5)] and the proportion of patients with major LARS (score >30) went from 15/17 (88%) to 7/17 (41%), ( P =0.001). In the P-O group, the mean (SD) LARS score decreased by 12% [from 37 (4.8) to 32.6 (9.1)], and the proportion of major LARS went from 19/21 (90%) to 16/21 (76%). After crossover, LARS scores deteriorated again in the O-P group receiving placebo, but further improved in the P-O group receiving ondansetron. Mean Vaizey scores and IBS QoL scores followed a similar pattern.

CONCLUSIONS

Ondansetron is a safe and simple treatment that appears to improve both symptoms and QoL in LARS patients.

Bibliometric analysis and visualization of research trends in total mesorectal excision in the past twenty years

BACKGROUND

Rectal cancer leads a major disease burden worldwide. Total mesorectal excision (TME) is the standard treatment for locally advanced or node-positive rectal cancer, while attempts to improve the surgery such as laparoscopic and transanal TME are widely used but have their inherent limitations. This bibliometric study analyzed research trends, cooperation, and knowledge dissemination on TME over the past 20 years to inform future directions.

METHODS

Relevant literature from 2003 to 2023 was extracted from the Web of Science Core Collection and analyzed with VOSviewer, CiteSpace, and R for publication patterns, countries, institutions, authors, and research hotspots.

RESULTS

Five thousand three hundred forty-five related publications were included, with rising annual output and citations. The US and China contributed the most studies, while the Netherlands had greater influence. Leiden University ranked first in publications. The top authors were Heald, Kapiteijn, Sauer, Nagtegaal, and Peeters. Research shifted from cancer-focused to patient-centered care and from radiotherapy/chemotherapy to advanced surgery. Multicenter trials became more common.

CONCLUSION

Although the United States and China have the largest number of publications, it should be noted that the influence of these two countries in the field of TME research is not the highest, which does not match the number of publications. In addition, telemedicine, interdisciplinary, medical-industrial integration, etc. may be potential directions for future research in the field of TME.

Clinical Management of Low Anterior Resection Syndrome: Review of the Current Diagnosis and Treatment

BACKGROUND

Low anterior resection syndrome (LARS) is a series of bowel dysfunction symptoms, including altered bowel frequency, irregular bowel rhythms, fecal incontinence, and constipation. LARS occurs in 80% of patients undergoing sphincter-preserving surgery, affecting patients' quality of life along with social avoidance. Different measurements and treatments have been raised to deal with LARS, but no systematic standard has been developed.

OBJECTIVE AND METHODS

To promote the standardization of clinical trials and clinical management of LARS, this review summarizes the latest findings up until 2023 regarding the diagnostic criteria, assessment protocols, and treatment modalities for postoperative LARS in rectal cancer.

RESULTS

The diagnostic criteria for LARS need to be updated to the definition proposed by the LARS International Collaborative Group, replacing the current application of the LARS score. In both clinical trials and clinical treatment, the severity of LARS should be assessed using at least one symptom assessment questionnaire, the LARS score or MSKCC BFI, and at least one scale related to quality of life. Anorectal manometry, fecoflowmetry, endoscopic ultrasonography, and pelvic floor muscle strength testing are recommended to be adopted only in clinical trials. After analysis of the latest literature on LARS treatment, a stepwise classification model is established for the standardized clinical management of LARS. Patients with minor LARS can start with first-line treatment, including management of self-behavior with an emphasis on diet modification and medication. Lamosetron, colesevelam hydrochloride, and loperamide are common antidiarrheal agents. Second-line management indicates multi-mode pelvic floor rehabilitation and transanal irrigation. Patients with major LARS should select single or several treatments in second-line management. Refractory LARS can choose antegrade enema, neuromodulation, or colostomy.

CONCLUSIONS

In clinical trials of LARS treatment between 2020 and 2022, the eligibility criteria and evaluation system have been variable. Therefore, it is urgent to create a standard for the diagnosis, assessment, and treatment of LARS. Failure to set placebos and differentiate subgroups are limitations of many current LARS studies. Randomized controlled trials comparing diverse therapies and long-term outcomes are absent, as well. Moreover, a new scale needs to be developed to incorporate the patient's perspective and facilitate outpatient follow-up. Though the establishment of a stepwise classification model for LARS treatment here is indispensable, the refinement of the guidelines may be improved by more standardized studies.

Low anterior resection syndrome

Low anterior resection syndrome (LARS) is the distressful defecatory functional problem after sphincter-saving surgery for rectal cancer. Although the symptoms of fecal urgency, frequency, and incontinence may develop in most of the patients after surgery, there is no definitive treatments for LARS. Multifactorial etiologies and various risk factors have been identified, but the reduction of storage capacity in the rectum is one of the main reasons for LARS. Anal sphincter muscle or nerve damage during rectoanal resection or anastomosis construction, and intersphincteric resection for low-lying tumors or hand-sewing anastomosis, are the absolute risk factors for LARS. Preoperative radiotherapy, postoperative complications, such as anastomosis leakage, or longer duration of stoma, are also risk factors. The severity of LARS can be confirmed using the LARS score questionnaire. The questionnaire has been translated to numerous language versions including Korean and have been validated. Diverse empirical treatments, such as loperamide, fiber, probiotics, or enema, have been tried, but the safety and efficacy have not been verified yet. The 5-Hydroxytryptamine (5-HT) receptor antagonist, ramosetron, used for diarrhea-dominant irritable bowel syndrome, is one potential drug for relieving the symptoms of major LARS. A randomized-controlled trial suggested the use of ramosetron could be safe and efficacious for patients who have major LARS after sphincter-saving rectal cancer surgery. Novel techniques or drugs for relieving the symptoms of LARS should be developed more and further studies are necessary.

Gut microbiome associated with low anterior resection syndrome after rectal cancer surgery

This study aimed to assess the likely association of gut microbiome with low anterior resection syndrome (LARS) symptoms. Postoperative stool samples from patients with minor or major LARS after sphincter-preserving surgery (SPS) for rectal cancer were collected and analyzed using 16S ribosomal RNA sequencing method. The symptom patterns of LARS were classified into two groups (PC1LARS, PC2LARS) using principal component analysis. The dichotomized sum of questionnaire items (sub1LARS, sub2LARS) was used to group patients according to the main symptoms. According to microbial diversity, enterotype, and taxa, PC1LARS and sub1LARS were associated with frequency-dominant LARS symptoms and patients, while PC2LARS and sub2LARS were grouped as incontinence-dominant LARS symptoms and patients. Butyricicoccus levels decreased while overall LARS scores increased. The α-diversity richness index Chao1 showed a significantly negative correlation in sub1LARS and a positive correlation in sub2LARS. In sub1LARS, the severe group showed a lower Prevotellaceae enterotype and higher Bacteroidaceae enterotype than the mild group. Subdoligranulum and Flavonifractor showed a negative and a positive correlation with PC1LARS, respectively, while showing a negative relationship with PC2LARS. Lactobacillus and Bifidobacterium were negatively correlated to PC1LARS. Frequency-dominant LARS had decreased diversity of gut microbiome and showed lower levels of lactic acid-producing bacteria.

Systematic review and meta-analysis of randomized clinical trials on the treatment of low anterior resection syndrome

BACKGROUND

We conducted a systematic review of randomized clinical trials on treating low anterior resection syndrome to help inform current practice.

METHODS

This Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review of randomized clinical trials involved different treatments for low anterior resection syndrome. The risk of bias 2 tool was used to assess the risk of bias. The main outcomes were improvement in low anterior resection syndrome after treatment assessed by change in low anterior resection syndrome, fecal incontinence scores, and adverse treatment effects.

RESULTS

After an initial screening of 1,286 studies, 7 randomized clinical trials were included. Sample sizes ranged between 12 to 104 patients. Posterior tibial nerve stimulation was the most frequently assessed treatment in 3 randomized clinical trials. The weighted mean difference between posterior tibial nerve stimulation and medical treatment or sham therapy in follow-up low anterior resection syndrome score (-3.31, P = .157) was insignificant. Transanal irrigation reduced major low anterior resection syndrome symptoms by 61.5% compared with 28.6% after posterior tibial nerve stimulation with a significantly lower 6-month follow-up low anterior resection syndrome score. Pelvic floor training achieved better improvement in low anterior resection syndrome than standard care (47.8% vs 21.3%) at 6 months, but this was not maintained at 12 months (40.0% vs 34.9%). Ramosetron was associated with a greater short-term improvement in major low anterior resection syndrome (23% vs 8%) and a lower low anterior resection syndrome score (29.5 vs 34.6) at 4-weeks follow-up than Kegels or Sitz baths. No significant improvement in bowel function was noted after probiotics use as probiotics and placebo had similar follow-up low anterior resection syndrome scores (33.3 vs 36).

CONCLUSION

Transanal irrigation was associated with improvement in low anterior resection syndrome according to 2 trials, and ramosetron showed promising short-term results in one trial. Posterior tibial nerve stimulation had a marginal benefit compared with standard care. In contrast, pelvic floor training was associated with short-term symptomatic improvement, and probiotics showed no tangible improvement in low anterior resection syndrome symptoms. Firm conclusions cannot be drawn due to the small number of trials published.