Neoadjuvant Therapy for Locally Advanced Rectal Cancer: Recent Advances and Ongoing Challenges

Oncological outcomes of local excision versus radical surgery for early rectal cancer in the context of staging and surveillance: A systematic review and meta-analysis

BACKGROUND

Local resection (LR) methods for rectal cancer are generally considered in the palliative setting or for patients deemed a high anaesthetic risk. This systematic review and meta-analysis aimed to compare oncological outcomes of LR and radical resection (RR) for early rectal cancer in the context of staging and surveillance assessment.

METHODS

A literature search of MEDLINE, Embase and Emcare databases was performed for studies that reported data on clinical outcomes for both LR and RR for early rectal cancer from January 1995 to April 2023. Meta-analysis was performed using random-effect models and between-study heterogeneity was assessed. The quality of assessment was assessed using the Newcastle-Ottawa Scale for observational studies and the Cochrane Risk of Bias 2.0 tool for randomised controlled trials.

RESULTS

Twenty studies with 12,022 patients were included: 6,476 patients had LR and 5,546 patients underwent RR. RR led to an improvement in 5-year overall survival (OR 1.84; 95 % CI 1.54-2.20; p < 0.0001; I2 20 %) and local recurrence (OR 3.06; 95 % CI 2.02-4.64; p < 0.0001; I2 39 %) when compared to LR. However, when staging and surveillance methods were clearly adopted in LR cases, there was an improvement in R0 rates (96.7 % vs 85.6 %), 5-year disease-free survival (93.0 % vs 77.9 %) and overall survival (81.6 % vs 79.0 %) compared to when staging and surveillance was not reported/performed.

CONCLUSIONS

LR may be appropriate for selected patients without poor prognostic factors in early rectal cancer. This study also highlights that there is currently no single standardised staging or surveillance approach being adopted in the management of early rectal cancer. A more specified and standardised preoperative staging for patient selection as well as clinical and image-based surveillance protocols is needed.

The survival prediction of advanced colorectal cancer received neoadjuvant therapy-a study of SEER database

PURPOSE

The aim of study was to screen factors associated with the overall survival of colorectal cancer patients with lymph nodes metastasis who received neoadjuvant therapy and construct a nomogram model.

METHODS

All enrolled subjects of the SEER database were randomly assigned to the training and testing group in a ratio of 3:2. The patients of Tangdu Hospital were seemed as validation group. Univariate cox regression analysis, lasso regression and random forest survival were used to screen variables related to the survival of advanced CRC patients received neoadjuvant therapy in the training group. Area under curves were adopted to evaluate the 1,3,5-year prediction value of the optimal model in three cohorts. Calibration curves were drawn to observe the prediction accuracy of the nomogram model. Decision curve analysis was used to assess the potential clinical value of the nomogram model.

RESULTS

A total of 1833 subjects were enrolled in this study. After random allocation, 1055 cases of the SEER database served as the training group, 704 cases as the testing group and 74 patients from our center as the external validation group. Variables were screened by univariate cox regression used to construct a nomogram survival prediction model, including M, age, chemotherapy, CEA, perineural invasion, tumor size, LODDS, liver metastasis and radiation. The AUCs of the model for predicting 1-year OS in the training group, testing and validation group were 0.765 (0.703,0.827), 0.772 (0.697,0.847) and 0.742 (0.601,0.883), predicting 3-year OS were 0.761 (0.725,0.780), 0.742 (0.699,0.785), 0.733 (0.560,0.905) and 5-year OS were 0.742 (0.711,0.773), 0.746 (0.709,0.783), 0.838 (0.670,0.980), respectively. The calibration curves showed the difference between prediction probability of the model and the actual survival was not significant in three cohorts and the decision curve analysis revealed the practice clinical application value. And the prediction value of model was better for young CRC than older CRC patients.

CONCLUSION

A nomogram model including LODDS for the prognosis of advanced CRC received neoadjuvant therapy was constructed and verified based on the SEER database and single center practice. The accuracy and potential clinical application value of the model performed well, and the model had better predictive value for EOCRC than LOCRC.

Compare clinical efficacy and safety of neoadjuvant therapy and neoadjuvant chemoradiotherapy for locally advanced rectal cancer: Meta-analysis

BACKGROUND

To compare the efficacy and safety of total neoadjuvant therapy (TNT) and neoadjuvant chemoradiotherapy (nCRT) in the treatment of middle and low locally advanced rectal cancer. Our study will systematically collect and integrate studies to evaluate the ability of these two treatments to improve tumor shrinkage rates, surgical resection rates, tumor-free survival, and severe adverse events.

AIM

To provide clinicians and patients with more reliable treatment options to optimize treatment outcomes and quality of life for patients with locally advanced rectal cancer by comparing the advantages and disadvantages of the two treatment options.

METHODS

A full search of all clinical studies on the effectiveness and safety of TNT and nCRT for treating locally advanced rectal cancer identified in Chinese (CNKI, Wanfang, China Biomedical Literature Database) and English (PubMed, Embase) databases was performed. Two system assessors independently screened the studies according to the inclusion and exclusion criteria. Quality evaluation and data extraction were performed for the included literature. We used RevMan 5.3 software to perform a meta-analysis of the pathologic complete response (pCR) rate, T stage degradation rate, resection 0 (R0) rate, anal grade 3/4 acute toxicity rate, perioperative complications, overall survival (OS), and disease-free survival (DFS) in the TNT and nCRT groups.

RESULTS

Finally, 14 studies were included, six of which were randomized controlled studies. A total of 3797 patients were included, including 1865 in the TNT group and 1932 in the nCRT group. The two sets of baseline data were comparable. The results of the meta-analysis showed that the pCR rate [odds ratio (OR) = 1.57, 95% confidence interval (CI): 1.30-1.90, P < 0.00001], T stage degradation rate (OR = 2.16, 95%CI: 1.63-2.57, P < 0.00001), and R0 resection rate (OR = 1.42, 95%CI: 1.09-1.85, P = 0.009) were significantly greater in the nCRT group than in the nCRT group. There was no significant difference in the incidence of grade 3/4 acute toxicity or perioperative complications between the two groups. The 5-year OS [hazard ratio (HR) = 0.84, 95%CI: 0.69-1.02, P = 0.08] and DFS (HR = 0.94, 95%CI: 0.03-1.39, P = 0.74) of the TNT group were similar to those of the nCRT group.

CONCLUSION

TNT has greater clinical efficacy and safety than nCRT in the treatment of locally advanced rectal cancer.

Pharmacological modulation of RB1 activity mitigates resistance to neoadjuvant chemotherapy in locally advanced rectal cancer

Resistance to neoadjuvant chemotherapy leads to poor prognosis of locally advanced rectal cancer (LARC), representing an unmet clinical need that demands further exploration of therapeutic strategies to improve clinical outcomes. Here, we identified a noncanonical role of RB1 for modulating chromatin activity that contributes to oxaliplatin resistance in colorectal cancer (CRC). We demonstrate that oxaliplatin induces RB1 phosphorylation, which is associated with the resistance to neoadjuvant oxaliplatin-based chemotherapy in LARC. Inhibition of RB1 phosphorylation by CDK4/6 inhibitor results in vulnerability to oxaliplatin in both intrinsic and acquired chemoresistant CRC. Mechanistically, we show that RB1 modulates chromatin activity through the TEAD4/HDAC1 complex to epigenetically suppress the expression of DNA repair genes. Antagonizing RB1 phosphorylation through CDK4/6 inhibition enforces RB1/TEAD4/HDAC1 repressor activity, leading to DNA repair defects, thus sensitizing oxaliplatin treatment in LARC. Our study identifies a RB1 function in regulating chromatin activity through TEAD4/HDAC1. It also provides the combination of CDK4/6 inhibitor with oxaliplatin as a potential synthetic lethality strategy to mitigate oxaliplatin resistance in LARC, whereby phosphorylated RB1/TEAD4 can serve as potential biomarkers to guide the patient stratification.

Pre-operative Neo-adjuvant Chemotherapy Related miRNAs as Key Regulators and Therapeutic Targets in Colorectal Cancer

BACKGROUND

In colorectal cancer, the investigation of cancer pathogenesis and the determination of the relevant gene and gene pathways is particularly important to provide a basis for treatment-oriented studies. miRNAs which affect gene regulation in the molecular pathogenesis of cancer, have an active role in carcinogenesis. In the literature, miRNA expression levels have been associated with metastasis and prognosis in different cancers.

OBJECTIVE

In our study, expression profiling of miRNAs involved in oncogenic and apoptotic pathways in patients with locally advanced colorectal cancer receiving neoadjuvant therapy was performed.

METHODS

miRNAs were isolated from three different FFPE tissue samples taken at different times of the same patient (tumor tissue taken at the time of diagnosis, normal tissue samples, and after neoadjuvant therapy). The expression analysis of 84 miRNAs determined by PCR array (Fluidigm, USA) and mediated meta-analysis was performed comparatively to each study and non-cancerous control group. Evaluations were performed with ΔΔCT calculations.

RESULTS

As a result of the miRNA PCR array study, in addition to differences were observed in miRNA expression between control and study groups. The potential biomarkers which were hsamiR- 215-5p, hsa-miR-9-59, hsa-miR-193a-5p, hsa-miR-206, hsa-miR-1, hsa-miR-96-5p have been detected for possible treatment resistance, prognosis and predispositions to cancers.

CONCLUSION

In patients with colorectal cancer, miRNA expression in the tumoral regions before and after neoadjuvant therapy has represented a variable pattern. It has been shown that miRNA studies can be used to predict the clinical course and response to treatment with differences in expression levels. It has been concluded that specific miRNAs may be candidate biomarkers for colorectal cancer.

.

Prognostic prediction value of the clinical-radiomics tumour-stroma ratio in locally advanced rectal cancer

PURPOSE

To develop and validate a radiomics model based on high-resolution T2WI and a clinical-radiomics model for tumour-stroma ratio (TSR) evaluation with a gold standard of TSR evaluated by rectal specimens without therapeutic interference and further apply them in prognosis prediction of locally advanced rectal cancer (LARC) patients who received neoadjuvant chemoradiotherapy.

METHODS

A total of 178 patients (mean age: 59.35, range 20-85 years; 65 women and 113 men) with rectal cancer who received surgery alone from January 2016 to October 2020 were enrolled and randomly separated at a ratio of 7:3 into training and validation sets. A senior radiologist reviewed after 2 readers manually delineated the whole tumour in consensus on preoperative high-resolution T2WI in the training set. A total of 1046 features were then extracted, and recursive feature elimination embedded with leave-one-out cross validation was applied to select features, with which an MR-TSR evaluation model was built containing 6 filtered features via a support vector machine classifier trained by comparing patients' pathological TSR. Stepwise logistic regression was employed to integrate clinical factors with the radiomics model (Fusion-TSR) in the training set. Later, the MR-TSR and Fusion-TSR models were replicated in the validation set for diagnostic effectiveness evaluation. Subsequently, 243 patients (mean age: 53.74, range 23-74 years; 63 women and 180 men) with LARC from October 2012 to September 2017 who were treated with NCRT prior to surgery and underwent standard pretreatment rectal MR examination were enrolled. The MR-TSR and Fusion-TSR were applied, and the Kaplan-Meier method and log-rank test were used to compare the survival of patients with different MR-TSR and Fusion-TSR. Cox proportional hazards regression was used to calculate the hazard ratio (HR).

RESULTS

Both the MR-TSR and Fusion-TSR models were validated with favourable diagnostic power: the AUC of the MR-TSR was 0.77 (p = 0.01; accuracy = 69.8 %, sensitivity = 88.9 %, specificity = 65.9 %, PPV = 34.8 %, NPV = 96.7 %), while the AUC of the Fusion-TSR was 0.76 (p = 0.014; accuracy = 67.9 %, sensitivity = 88.9 %, specificity = 63.6 %, PPV = 33.3 %, NPV = 96.6 %), outperforming their effectiveness in the training set: the AUC of the MR-TSR was 0.65 (p = 0.035; accuracy = 66.4 %, sensitivity = 61.9 %, specificity = 67.3 %, PPV = 27.7 %, NPV = 90.0 %), while the AUC of the Fusion-TSR was 0.73 (p = 0.001; accuracy = 73.6 %, sensitivity = 71.4 %, specificity = 74.0 %, PPV = 35.73 %, NPV = 92.8 %). With further prognostic analysis, the MR-TSR was validated as a significant prognostic factor for DFS in LARC patients treated with NCRT (p = 0.020, HR = 1.662, 95 % CI = 1.077-2.565), while the Fusion-TSR was a significant prognostic factor for OS (p = 0.005, HR = 2.373, 95 % CI = 1.281-4.396).

CONCLUSIONS

We developed and validated a radiomics TSR and a clinical-radiomics TSR model and successfully applied them to better risk stratification for LARC patients receiving NCRT and for better decision making.

Endoscopic ultrasound-guided injection of carbon nanoparticles suspension to label rectal cancer before neoadjuvant chemoradiotherapy: a retrospective cohort study

Background

Localization of the primary tumor and ensuring safe distal surgical margins (DSMs) following neoadjuvant chemoradiotherapy (nCRT) are challenging in locally advanced rectal cancers (LARCs). This study investigated the effectiveness of carbon nanoparticles suspension (CNS) for labeling the primary tumor and allowing precise tumor resection after nCRT.

Methods

Clinicopathological data of LARC patients who underwent nCRT followed by laparoscopic radical anal preservation surgery at our center between January 2018 and February 2023 were prospectively collected. The patients were divided into the CNS tattooed (CNS) and non-tattooed (control) groups. In the CNS group, CNS was injected in four quadrants on the anal side 1 cm away from the lower tumor margin. DSMs were determined through intraoperative distal rectal examination in the control group and observation of CNS tattoos in the CNS group. DSM lengths and positive DSM rates were compared between the two groups to analyse the feasibility and effectiveness of CNS for labeling LARCs before nCRT.

Results

There was no statistically significant difference in the basic demographic data, effectiveness of nCRT, or post-operative recovery rates between the two groups (all P > 0.05). In the CNS group, CNS tattoos were observed on the outside of the rectal wall, with an overall efficiency of 87.1% (27/31). The CNS group had fewer positive DSMs and safer DSM lengths (2.73 ± 0.88 vs 2.12 ± 1.15 cm, P = 0.012) than the control group (P < 0.05).

Conclusions

Endoscopic ultrasound-guided injection of CNS tattoos before nCRT could effectively label the LARCs, ensuring safe DSMs during anus-preserving surgeries (Chictr.org.cn No.: ChiCTR2300068991).

Can neoadjuvant chemoradiotherapy combined with immunotherapy benefit patients with microsatellite stable locally advanced rectal cancer? a pooled and integration analysis

Objective

To assess the clinical efficacy of neoadjuvant chemoradiotherapy combined with immunotherapy for patients with microsatellite stable (MSS) locally advanced rectal cancer and provide evidence to support clinical decision-making.

Methods

A systematic search was conducted on the PubMed, Embase, Cochrane Collaboration databases, conference summaries, and Chinese databases for clinical studies that investigated neoadjuvant chemoradiotherapy combined with immunotherapy for the treatment of locally advanced rectal cancer with MSS status. The search spanned from the inception of each database through July 2023. Data from the identified studies were extracted using a pre-designed table, and efficacy outcomes were analyzed. An integrated analysis was conducted using Stata 12.0 software.

Results

Eight studies were included, comprising 204 patients with locally advanced MSS rectal cancer who received chemoradiotherapy combined with immunotherapy. The integrated analysis revealed a pathologic complete remission rate of 0.33, a sphincter preservation rate of 0.86, an R0 resection rate of 0.83, a major pathologic remission rate of 0.33, and a clinical complete remission rate of 0.30.

Conclusion

Neoadjuvant chemoradiotherapy combined with immunotherapy demonstrates significant short-term efficacy in MSS-type locally advanced rectal cancer, notably enhancing the pathologic complete remission and sphincter preservation rates. This combination is a recommended treatment for patients with MSS-type rectal cancer.

Total neoadjuvant therapy versus standard neoadjuvant treatment strategies for the management of locally advanced rectal cancer: network meta-analysis of randomized clinical trials

BACKGROUND

This study compared the advantages and disadvantages of total neoadjuvant therapy (TNT) strategies for patients with locally advanced rectal cancer, compared with the more traditional multimodal neoadjuvant management strategies of long-course chemoradiotherapy (LCRT) or short-course radiotherapy (SCRT).

METHODS

A systematic review and network meta-analysis of exclusively RCTs was undertaken, comparing survival, recurrence, pathological, radiological, and oncological outcomes. The last date of the search was 14 December 2022.

RESULTS

In total, 15 RCTs involving 4602 patients with locally advanced rectal cancer, conducted between 2004 and 2022, were included. TNT improved overall survival compared with LCRT (HR 0.73, 95 per cent credible interval 0.60 to 0.92) and SCRT (HR 0.67, 0.47 to 0.95). TNT also improved rates of distant metastasis compared with LCRT (HR 0.81, 0.69 to 0.97). Reduced overall recurrence was observed for TNT compared with LCRT (HR 0.87, 0.76 to 0.99). TNT showed an improved pCR compared with both LCRT (risk ratio (RR) 1.60, 1.36 to 1.90) and SCRT (RR 11.32, 5.00 to 30.73). TNT also showed an improvement in cCR compared with LCRT (RR 1.68, 1.08 to 2.64). There was no difference between treatments in disease-free survival, local recurrence, R0 resection, treatment toxicity or treatment compliance.

CONCLUSION

This study provides further evidence that TNT has improved survival and recurrence benefits compared with current standards of care, and may increase the number of patients suitable for organ preservation, without negatively influencing treatment toxicity or compliance.

Pathologic complete response to TNT + camrelizumab for rectal cancer with surgical anus-preservation: case report and literature review

Background

This case report demonstrates the efficacy of total neoadjuvant therapy (TNT) based on pathological complete response (PCR). We also discuss the surgical approach to preserving the anus and its perioperative management.

Case presentaion

The patient was a 26-year-old woman, with blood in the stool and stool thinning for over two months. Preoperative examination revealed locally advanced rectal cancer invading the left anal raphe and enlarged lymph nodes adjacent to the left internal iliac vessels. The lesion was preoperatively classified as T4bN1bM0 IIIC. Considering the size and depth of the tumor, it was difficult to have sufficient margins for radical resection, and the tumor was too close to the anal orifice. Considering the patient's youth and strong desire to preserve the anus, it was decided to use TNT combined with a camrelizumab regimen. After the entire course of neoadjuvant radiotherapy, the tumor size significantly reduced in fibrotic manifestations, and no enlargement of the lymph nodes adjacent to the left internal iliac vessels was observed. She underwent robotic laparoscopic ultra-low anterior rectal resection, left lateral lymph node dissection, and temporary ileostomy, and no significant residue was observed after all bowel tubes were taken for examination, nor was there cancerous involvement at the distal or radial cut edges, or metastasis. The patient was discharged nine days postoperatively, and no major complications were detected. Follow-up was performed without adjuvant chemotherapy.

Conclusions

TNT may be a better surgical option for preserving the anus and for complete radical resection in patients with LARC for whom Miles' resection is indicated.

Regional transarterial chemoembolization combined with chemoradiotherapy for locally advanced rectal cancer: a retrospective study of a new combination

Objectives

Locally advanced rectal cancer (LARC) has a high risk of distant metastasis (DM). Currently, many treatment courses of LARC have arisen, but patients' DM status has not significantly improved. This study was designed to compare the effect between preoperative regional transarterial chemoembolization combined with neoadjuvant chemoradiotherapy and standard neoadjuvant therapy on preventing DM in patients with LARC.

Methods

A total of 81 LARC patients between July 2013 and May 2018 were enrolled in this retrospective study. Among them, 44 patients received preoperative regional transarterial chemoembolization combined with concurrent chemoradiotherapy (the interventional group), and 37 patients received only neoadjuvant chemoradiotherapy (the control group). The baseline data; preoperative toxicities; postoperative DM rate within 1, 2, and 3 years; and postoperative complications were compared between the two groups.

Results

All patients successfully completed their treatments. There were no significant differences between the two groups in age, gender, tumor size, distance between the tumor and anal verge, CEA level, lymphovascular invasion, or tumor stage before treatment. The pathological T staging post-treatment in the interventional group was significantly reduced compared to that of the control group (p = 0.025). There were no significant differences between groups in DM rates within 1 and 2 years after surgery. In terms of DM rate within 3 years after surgery, the interventional group was significantly lower than that of the control group (9.1% vs. 29.7%, p = 0.036).

Conclusion

Preoperative regional transarterial chemoembolization combined with concurrent chemoradiotherapy may play an important role in reducing postoperative DM in LARC.

Emerging evidence of immunotherapy for colorectal cancer

Since the advent of immune checkpoint inhibitors, which modulate the interplay between the tumor cell and immune system, immunotherapy has become widely recognized as a new standard treatment for cancers including microsatellite instability-high (MSI-H) colorectal cancer. Immune checkpoint inhibitors such as pembrolizumab and nivolumab (anti-PD-1 antibodies) that act in the effector phase of T cells and ipilimumab (anti-CTLA-4 antibody) that acts mainly in the priming phase are now in clinical use. These antibodies have shown therapeutic efficacy in MSI colorectal cancer patients who have failed to respond to existing standard therapies. Pembrolizumab is also strongly recommended as first-line therapy for MSI-H metastatic colorectal cancer. Therefore, the MSI status and tumor mutation burden of the tumor should be clarified before starting treatment. Because many patients do not respond to immune checkpoint inhibitors, combination therapies with immune checkpoint inhibitors, including chemotherapy, radiotherapy, or molecularly targeted agents, are being investigated. Furthermore, treatment methods for preoperative adjuvant therapy for rectal cancer are being developed.

Meta-analysis of neoadjuvant immunotherapy for non-metastatic colorectal cancer

Background

Immunotherapy has been approved for the treatment of metastatic colorectal cancer. The efficacy and safety of neoadjuvant immunotherapy for the treatment of non-metastatic colorectal cancer remains unclear. We tried to explore clinical effect of neoadjuvant immunotherapy in the treatment of non-metastatic colorectal cancer.

Methods

We searched the databases (PubMed, Wanfang Embase, Cochrane Library and China National Knowledge Infrastructure databases) to obtain suitable articles up to September 2022. The primary outcomes of pathological complete response (pCRs), major pathological response (MPR), objective response rate (ORR), R0-resection and anus preserving rate were collected and evaluated. Secordary outcomes (pCRs and MPR) of subgroup analysis between deficient mismatch repair/microsatellite instability-high group (dMMR/MSI-H) and proficient mismatch repair/microsatellite stable group (pMMR/MSS) and outcomes for rectal cancer were analyzed for the final results.

Results

We included ten articles and 410 cases of non-metastatic colorectal cancer with neoadjuvant immunotherapy. There were 113 (27.5%) cases with the dMMR/MSI-H status and 167 (40.7%) cases with the pMMR/MSS status. pCRs was found in 167/373 (44.6%) patients (ES: 0.49, 95% CI: 0.36 to 0.62, P<0.01, chi² = 65.3, P<0.01, I ² = 86.2%) and MPR was found in 194/304 (63.8%) patients (ES: 0.66, 95% CI: 0.54 to 0.78, P<0.01, chi² = 42.55, P<0.01, I ² = 81.2%) with the random-effects model and huge heterogeneity. In the subgroup analysis, pCRs was higher in the dMMR/MSI-H group than the pMMR/MSS group in the fixed-effects model with minimal heterogeneity (OR: 3.55, 95% CI: 1.74 to 7.27, P<0.01, chi² = 1.86, P=0.6, I ² = 0%). pCRs was found in 58/172 (33.9%) rectal cancer patients (ES: 0.33, 95% CI: 0.26 to 0.40, P<0.01, chi² = 3.04, P=0.55, I ² = 0%) with the fixed-effects model and little heterogeneity.

Conclusion

Neoadjuvant immunotherapy could increase pCRs and MPR rate for non-metastatic colorectal cancer. Neoadjuvant immunotherapy could achieve better pCRs rate in dMMR/MSI-H group than in the pMMR/MSS group. Neoadjuvant immunotherapy could be another treatment option for non-metastatic colorectal cancer.

Systematic review registration

https://www.crd.york.ac.uk/prospero/#myprospero, identifier CRD42022350523.

Gut microbiome in tumorigenesis and therapy of colorectal cancer

Colorectal cancer (CRC) is the malignant tumor with the highest incidence in the digestive system, and the gut microbiome plays a crucial role in CRC tumorigenesis and therapy. The gastrointestinal tract is the organ harboring most of the microbiota in humans. Changes in the gut microbiome in CRC patients suggest possible host-microbe interactions, thereby hinting the potential tumorigenesis, which provides new perspective for preventing, diagnosing, or treating CRC. In this review, we discuss the effects of gut microbiome dysbiosis on CRC, and reveal the mechanisms by which gut microbiome dysbiosis leads to CRC. Gut microbiome modulation with the aim to reverse the established gut microbial dysbiosis is a novel strategy for the prevention and treatment of CRC. In addition, this review summarizes that probiotic antagonize CRC tumorigenesis by protecting intestinal barrier function, inhibiting cancer cell proliferation, resisting oxidative stress, and enhancing host immunity. Finally, we highlight clinical applications of the gut microbiome, such as gut microbiome analysis-based biomarker screening and prediction, and microbe modulation-based CRC prevention, treatment enhancement, and treatment side effect reduction. This review provides the reference for the clinical application of gut microbiome in the prevention and treatment of CRC.

Current Surgical Methods in Local Rectal Excision

Background

The treatment of rectal cancer has evolved with the advancement of surgical techniques. Less invasive approaches are becoming more accepted as the primary treatment method.

Summary

Such methods as transanal excision, transanal endoscopic microsurgery, and transanal minimally invasive surgery can reduce morbidity and mortality rates. However, not all patients are suitable candidates for these procedures, and proper diagnostics are necessary to establish indications. Compared to total mesorectal excision, transanal excision techniques have been shown to have fewer complications and comorbidities while still being able to remove cancerous tissue entirely. Transanal excision is the simplest method, where the operator removes visible rectal lesions. The basic principle of transanal endoscopic microsurgery is to dilate the rectum mechanically and by air insufflation and then use special surgical instruments to remove suspicious lesions under the vision of a telescope. Transanal minimally invasive surgery combines transanal endoscopic microsurgery and single-incision laparoscopic surgery, making the hard-to-reach proximal rectum accessible to classic laparoscopic instruments.

Key Message

Local excision techniques, when used as a monotherapy for treating patients with rectal cancer, have established themselves as a curative and less radical treatment for strictly selected patients with early rectal carcinoma, leading to improved quality of life. When combined with other modalities such as neoadjuvant chemoradiotherapy, total neoadjuvant therapy, and immunotherapy, transanal surgery can be offered to patients with locally advanced rectal cancer as part of the organ preservation strategy. This review will discuss the patient selection and technical aspects of transanal surgery, showcasing its current role in treating rectal carcinoma.

Oncological outcomes of multimodality treatment for patients undergoing surgery for locally recurrent rectal cancer: A systematic review

BACKGROUND

There are several strategies in the management of locally recurrent rectal cancer (LRRC) with the optimum treatment yet to be established. This systematic review aims to compare oncological outcomes in patients undergoing surgery for LRRC who underwent neoadjuvant radiotherapy or chemoradiotherapy (CRT), adjuvant CRT, surgery only or surgery and intraoperative radiotherapy (IORT).

METHODS

A literature search of MEDLINE, EMBASE and CINAHL was performed for studies that reported data on oncological outcomes for the different treatment modalities in patients with LRRC from January 1990 to January 2022. Weighted means were calculated for the following outcomes: postoperative resection status, local control, and overall survival at 3 and 5 years.

RESULTS

Fifteen studies of 974 patients were included and they received the following treatment: 346 neoadjuvant radiotherapy, 279 neoadjuvant CRT, 136 adjuvant CRT, 189 surgery only, and 24 surgery and IORT. The highest proportion of R0 resection was found in the neoadjuvant CRT group followed by neoadjuvant radiotherapy and adjuvant CRT groups (64.07% vs 52.46% vs 47.0% respectively). The neoadjuvant CRT group had the highest mean 5-year local control rate (49.50%) followed by neoadjuvant radiotherapy (22.0%). Regarding the 5-year overall survival rate, the neoadjuvant CRT group had the highest mean of 34.92%, followed by surgery only (29.74%), neoadjuvant radiotherapy (28.94%) and adjuvant CRT (20.67%).

CONCLUSIONS

The findings of this systematic review suggest that neoadjuvant CRT followed by surgery can lead to improved resection status, long-term disease control and survival in the management of LRRC. However, treatment strategies in LRRC are complex and further comparisons, particularly taking into account previous treatments for the primary rectal cancer, are required.

Prior endoscopic resection does not affect the outcome of secondary surgery for T1 colorectal cancer, a systematic review and meta-analysis

BACKGROUND

It remains unclear the effect of prior endoscopic resection (ER) on the secondary surgery (SS) for T1 colorectal cancer (CRC). This study aimed to compare the short- and long-term outcomes between primary surgery (PS) and ER followed by SS for T1 CRC.

METHODS

A systematic literature search was performed in PubMed and Ovid for studies comparing PS with ER followed by SS for T1 colorectal cancer. The last search was performed on 18 May 2021. The primary outcomes were surgical parameters and the secondary outcomes were survival indicators. The meta-analysis was performed with Review Manager Software (version 5.3).

RESULTS

A total of fifteen studies published between 2013 and 2021 with 4349 patients were included in this meta-analysis finally. No significant difference was observed between the two groups for operative time (P = 0.75, WMD = 3.16, 95%CI [-15.88, 22.19], I² = 64%), blood loss (P = 0.86, WMD = 12.33, 95%CI [-122.99, 147.65], I² = 95%), and postoperative complications (P = 0.59, OR = 0.93, 95%CI [0.71, 1.22], I² = 0%). Besides, the two groups showed comparable survival outcomes, including overall recurrence rate (P = 0.15, OR = 0.78, 95%CI [0.56, 1.09], I² = 23%) and 5-year overall survival (P = 0.76, OR = 0.86, 95%CI [0.33, 2.25], I² = 0%). In the subgroup analysis for studies with propensity matching score or lesions located in the rectum, the results were not changed.

CONCLUSION

ER followed by SS is feasible for T1 CRC with high-risk factors. The prior ER would not bring additional adverse effects to the SS. More advanced tools should be developed to improve the diagnostic accuracy for the high-risk factors before treatment for T1 CRC.

Machine Learning Algorithms for Predicting Surgical Outcomes after Colorectal Surgery: A Systematic Review

BACKGROUND

Machine learning (ML) has been introduced in various fields of healthcare. In colorectal surgery, the role of ML has yet to be reported. In this systematic review, an overview of machine learning models predicting surgical outcomes after colorectal surgery is provided.

METHODS

Databases PubMed, EMBASE, Cochrane, and Web of Science were searched for studies using machine learning models for patients undergoing colorectal surgery. To be eligible for inclusion, studies needed to apply machine learning models for patients undergoing colorectal surgery. Absence of machine learning or colorectal surgery or studies reporting on reviews, children, study abstracts were excluded. The Probast risk of bias tool was used to evaluate the methodological quality of machine learning models.

RESULTS

A total of 1821 studies were analysed, resulting in the inclusion of 31 articles. A vast proportion of ML algorithms have been used to predict the course of disease and response to neoadjuvant chemoradiotherapy. Radiomics have been applied most frequently, along with predictive accuracies up to 91%. However, most studies included a retrospective study design without external validation or calibration.

CONCLUSIONS

Machine learning models have shown promising potential in predicting surgical outcomes after colorectal surgery. However, large-scale data is warranted to bridge the gap between calibration and external validation. Clinical implementation is needed to demonstrate the contribution of ML within daily practice.

Restoring HOXD10 Exhibits Therapeutic Potential for Ameliorating Malignant Progression and 5-Fluorouracil Resistance in Colorectal Cancer

Emerging evidence suggests that hypermethylation of HOXD10 plays an important role in human cancers. However, the biological and clinical impacts of HOXD10 overmethylation and its downstream targets in colorectal cancer remain unknown. We evaluated the methylation level of HOXD10 in paired cancer and normal tissues (n = 42) by using pyrosequencing, followed by validation of the methylation status of HOXD10 from The Cancer Genome Atlas (TCGA) datasets with 302 cancer tissues and 38 normal tissues. The biological function of HOXD10 was characterized in cell lines. We further evaluated the effects of HOXD10 and its targets on chemoresistance in our established resistant cell lines and clinical cohort (n = 66). HOXD10 was found frequently methylated in colorectal cancer, and its hypermethylation correlates with its low expression level, advanced disease, and lymph node metastasis. Functionally, HOXD10 acts as a tumor suppressor gene, in which HOXD10-expressing cells showed suppressed cell proliferation, colony formation ability, and migration and invasion capacity. Mechanistically, DNMT1, DNMT3B, and MeCP2 were recruited in the HOXD10 promoter, and demethylation by 5-Aza-2′-deoxycytidine (5-Aza-CdR) treatment or MeCP2 knockdown can sufficiently induce HOXD10 expression. HOXD10 regulates the expressions of miR-7 and IGFBP3 in a promoter-dependent manner. Restoration of the expression of HOXD10 in 5-fluorouracil (5-FU)-resistant cells significantly upregulates the expressions of miR-7 and IGFBP3 and enhances chemosensitivity to 5-FU. In conclusion, we provide novel evidence that HOXD10 is frequently methylated, silenced, and contributes to the development of colorectal cancers. Restoration of HOXD10 activates the expressions of miR-7 and IGFBP3 and results in an inhibited phenotype biologically, suggesting its potential therapeutic relevance in colorectal cancer (CRC).