No studies have examined the prognostic value of the log odds of negative lymph nodes/T stage (LONT) in locally advanced rectal cancer (LARC) treated with neoadjuvant chemoradiotherapy (nCRT). We aimed to assess the prognostic value of LONT and develop a machine learning model to predict overall survival (OS) and disease-free survival (DFS) in LARC patients treated with nCRT. The study included 820 LARC patients who received nCRT between September 2010 and October 2017. Univariate and multivariate Cox regression analyses identified prognostic factors, which were then used to develop risk assessment models with 9 machine learning algorithms. Model hyperparameters were optimized using random search and 10-fold cross-validation. The models were evaluated using metrics such as the area under the receiver operating characteristic curves (AUC), decision curve analysis, calibration curves, and precision and accuracy for predicting OS and DFS. Shapley's additive explanations (SHAP) was also used for model interpretation. The study included 820 patients, identifying LONT as a significant independent prognostic factor for both OS and DFS. Nine machine learning algorithms were used to create predictive models based on these factors. The extreme gradient boosting (XGB) model showed the best performance, with a mean AUC of 0.89 for OS and 0.83 for DFS in 10-fold cross-validation. Additionally, the predictions generated by the XGB model were analyzed using SHAP. Finally, we developed an online web-based calculator utilizing the XGB model to enhance the model's generalizability and to provide improved support for physicians in their decision-making processes. The study developed an XGB model utilizing LONT to predict OS and DFS in patients with LARC undergoing nCRT. Furthermore, an online web calculator was constructed using the XGB model to facilitate the model's generalization and to enhance physician decision-making.

This study attempted to establish a combined diagnostic model encompassing visualization of the middle rectal artery (MRA) and other imaging features to improve the diagnostic efficiency of lateral lymph node (LLN) metastasis, which is crucial for clinical decision-making in rectal cancer.

One hundred eleven patients receiving bilateral or unilateral lymph node dissection were enrolled, and 140 cases of LLN status on a certain unilateral pelvic sidewall were selected. Enhanced computed tomography (CT) was used to determine whether MRA was visible. Multivariable regression was used to establish a diagnostic model combining MRA visualization with other imaging features to predict LLN metastasis. Receiver operating characteristic (ROC) curve and area under the ROC curve (AUC) were used to test the diagnostic efficacy for LLN metastasis. Ten-fold cross-validation was completed to internally validate the diagnostic model.

Of the 140 LLNs harvested from 111 patients, 76 were positive and 64 were negative for metastases, respectively. The diagnostic model combining the MRA visualization and lymph node short diameter showed a greater efficiency than a single scale (AUC = 0.945, 95% confidence interval = 0.893-0.976, P < 0.001). The mean cross-validated AUC was 0.869 (95% confidence interval = 0.835-0.903).

Our results establish a combined diagnostic model with the help of MRA visualization to yield a high diagnostic efficiency of LLN metastasis in rectal cancer.

Pelvic lymph node dissection (PLND) is important for accurate staging and prognosis of prostate and/or bladder cancer. Several guidelines recommend extended PLND for patients with these cancers. However, the therapeutic benefits of extended PLND are unclear. One major reason is that the extent of PLND is not clearly defined. Thus, the working group for standardization of robot-assisted PLND, including nine experienced urologists for PLND in Japan, was launched in January 2023 by the Japanese Society of Endourology and Robotics. This study summarized the discussions to define the individual extent of PLND in urological surgery in a consensus meeting among these experienced urologists. The consensus meeting determined the extent of PLND based on arteries (veins) and anatomical membrane structures rather than a vague concept or approach toward PLND. This concept is expected to allow surgeons to implement the same extent of PLND. Finally, after a total of 10 online web conferences were held, we determined the extent of PLND for the obturator lymph node (LN) area, the internal iliac LN area, the external and common iliac LN area, and the presacral LN area according to the above rules. The extent of PLND suggested here currently does not have a clear therapeutic rationale. Therefore, the extent of our proposed PLND is by no means mandatory. We hope our definition of the extent of PLND will be supported by further evidence of therapeutic benefits for urologic cancers.

Developments in the multidisciplinary treatment of rectal cancer with advances in preoperative magnetic resonance imaging (MRI), surgical techniques, neoadjuvant chemoradiotherapy, and adjuvant chemotherapy have had a significant impact on patient outcomes, increasing the rates of curative surgeries and reducing pelvic recurrence. Patients with pelvic recurrence have worse prognoses, with an impact on morbidity and mortality. Although local recurrence is more frequent within 2 years of surgical resection of the primary tumor, late recurrence may occur. Clinical manifestations can vary from asymptomatic, nonspecific symptoms, to pelvic pain, bleeding, and fistulas. Synchronous metastatic disease occurs in approximately 50% of patients diagnosed with local recurrence. MRI plays a crucial role in posttreatment follow-up, whether by identifying viable neoplastic tissues or acting as a tool for therapeutic planning and assessing the resectability of these lesions. Locally recurrent tissues usually have a higher signal intensity than muscle on T2-weighted imaging. Thus, attention is required for focal heterogeneous lesions, marked contrast enhancement, early invasive behavior, and asymmetric appearance, which are suspicious for local recurrence. However, postsurgical inflammatory changes related to radiotherapy and fibrosis make it difficult to detect initial lesions. This study therefore aimed to review the main imaging patterns of pelvic recurrence and their implications for the surgical decision-making process. CRITICAL RELEVANCE STATEMENT: MRI plays a crucial role in the posttreatment follow-up of rectal cancer, whether by identifying viable neoplastic tissues or by acting as a tool for therapeutic planning. This study reviewed the main imaging patterns of pelvic recurrence. KEY POINTS: MRI aids in surgical planning and the detection of pelvic recurrence and postoperative complications. Being familiar with surgical techniques enables radiologists to identify expected MRI findings. Patterns of rectal cancer recurrence have been categorized by pelvic compartments. Neoplastic tissue may mimic postsurgical and postradiotherapy changes. Resectability of pelvic recurrence is highly related to lesion location.

This study attempted to compare short-term outcomes of laparoscopic surgery (LS), robot-assisted laparoscopic surgery (RS), and open surgery (OS) for lateral lymph-node dissection (LLND) in treatment of rectal cancer through network meta-analysis. Embase, Web of Science, PubMed, and The Cochrane Library databases were searched to collect cohort studies on outcomes of LS, RS, and OS for LLND for rectal cancer. Newcastle-Ottawa Scale (NOS) was utilized to evaluate the quality of cohort studies. Primary outcomes should at least include one of the following clinical outcome measures: operative time, blood loss, total lymph-node harvest, positive resection margin rate, postoperative complications, and postoperative hospital stay. A network meta-analysis was conducted using STATA software. Fourteen cohort studies including 8612 patients were eligible for inclusion. The network meta-analysis results showed that, in terms of intraoperative outcomes, the RS group had the longest operative time, while the OS group had the shortest; the LS and RS groups had significantly less blood loss than the OS group. In terms of histological outcomes, there were no significant differences in the total number of lymph nodes harvested and the positive margin rate among the LS, RS, and OS groups (P > 0.05). Regarding postoperative outcomes, the OS group had the highest probability of postoperative complications and the longest hospital stay, followed by the LS group, with the RS group being the lowest. RS was the best method in blood loss, postoperative complication rate, and postoperative hospital stay, followed by LS. OS had the shortest operative time and the highest blood loss.

Advanced rectal cancer with submesenteric lymph node metastasis is a common complication of advanced rectal cancer, which has an important impact on the treatment and prognosis of patients.

To investigate the clinical and pathological characteristics of inferior mesenteric artery (IMA) root lymph node metastases in patients with rectal cancer. The findings of this study provided us with fresh medical information that assisted us in determining the appropriate treatment for these patients.

Our study searched PubMed, Google Scholar, and other databases and searched the relevant studies and reports on the risk factors of IMA root lymph node metastasis of rectal cancer published in the self-built database until December 31, 2023. After data extraction, the Newcastle-Ottawa scale was used to evaluate the quality of the included literature, and RevMan5.3 software was used for meta-analysis and heterogeneity testing. The fixed effect modules without heterogeneity were selected to combine the effect size, and the random effect modules with heterogeneity were selected to combine the effect size. The cause of heterogeneity was found through sensitivity analysis, and the data of various risk factors were combined to obtain the final effect size, odds ratio (OR) value, and 95% confidence interval (CI). Publication bias was tested by drawing funnel plots.

A total of seven literature were included in this study. By combining the OR value of logistic multivariate regression and the 95%CI of various risk factors, we concluded that the risk factors for lymph node metastasis in the IMA region of rectal cancer were as follows: Preoperative carcinoembryonic antigen (CEA) > 5 ng/mL (OR = 0.32, 95%CI: 0.18-0.55, P < 0.05), tumor located above peritoneal reflexive (OR = 3.10, 95%CI: 1.78-5.42, P < 0.05), tumor size ≥ 5 cm (OR = 0.36, 95%CI: 0.22-0.57, P < 0.05), pathological type (mucinous adenocarcinoma/sig-ring cell carcinoma) (OR = 0.23, 95%CI: 0.13-0.41, P < 0.05), degree of tumor differentiation (low differentiation) (OR = 0.17, 95%CI: 0.10-0.31, P < 0.05), tumor stage (T3-4 stage) (OR = 0.11, 95%CI: 0.04-0.26, P < 0.05), gender and age were not risk factors for IMA root lymph node metastasis in rectal cancer (P > 0.05).

Preoperative CEA level, tumor location, tumor size, tumor pathologic type, tumor differentiation, and T stage were correlated with IMA root lymph node metastasis.

Malignant lateral lymph nodes (LLNs) in low, locally advanced rectal cancer can cause (ipsi-lateral) local recurrences ((L)LR). Accurate identification is, therefore, essential. This study explored LLN features to create an artificial intelligence prediction model, estimating the risk of (L)LR. This retrospective multicentre cohort study examined 196 patients diagnosed with rectal cancer between 2008 and 2020 from three tertiary centres in the Netherlands. Primary and restaging T2W magnetic resonance imaging and clinical features were used. Visible LLNs were segmented and used for a multi-channel convolutional neural network. A deep learning model was developed and trained for the prediction of (L)LR according to malignant LLNs. Combined imaging and clinical features resulted in AUCs of 0.78 and 0.80 for LR and LLR, respectively. The sensitivity and specificity were 85.7% and 67.6%, respectively. Class activation map explainability methods were applied and consistently identified the same high-risk regions with structural similarity indices ranging from 0.772-0.930. This model resulted in good predictive value for (L)LR rates and can form the basis of future auto-segmentation programs to assist in the identification of high-risk patients and the development of risk stratification models.

In the last decades, total mesorectal excision (TME) and neoadjuvant chemoradiotherapy (nCRT) have produced an undeniable improvement in the treatment of rectal cancer. However, local recurrence is still an important problem, and the effect of lateral lymph node (LLN) involvement on local recurrence is a controversial issue. The aim of this study was to investigate the effects of LLN status on local recurrence and survival in rectal cancers treated with nCRT + TME.

Clinical features, pre- and post-nCRT lateral pelvic region imaging, long-term local recurrence, and the survival outcomes of 114 patients who underwent nCRT + TME for rectal cancer were evaluated.

On MRI before nCRT, 20 (17.5%) patients had lateral lymph nodes (LLN+), and 94 (82.5%) patients had no lymph nodes in the lateral pelvic compartments (LLN-). Local recurrences at 1 year in LLN+ and LLN- patients were 3 (15.8%) and 2 (2.3%), respectively (p=0.039). Five-year local recurrence-free survival rates and the mean duration of recurrence-free survival in LLN+ and LLN- patients were 56.2%, 42.6 months, and 87.3% 66.9 months, respectively (p=0.001). Disease-free survival and overall survival were shorter in LLN+ patients, but the difference was not statistically significant (p=0.096 and p=0.46, respectively). In the multivariate analysis, LLN involvement was determined to be an independent risk factor for local recurrence-free survival (Hazard Ratio 4.54, p=0.003).

Lateral lymph node involvement causes local recurrence to remain high after nCRT + TME. LLN status should be considered in treatment planning. Further studies are needed to define precise criteria for LLN involvement and the effect of LLND on local recurrence and survival.

Rectal cancer remains a complex disease and a relevant global health issue, increasingly affecting also younger patients. This update review summarizes the current standard of care and discusses the individualized treatment approaches taking into consideration individual tumor characteristics and patients preferences.

Remaining "gray zones" of rectal cancer therapy warranting further prospective studies are identified including surgical approaches for rectal cancer, e.g., minimally invasive surgical techniques and lateral lymph node dissection for low rectal cancers. The emerging concept of a watch-and-wait strategy upon clinical complete response after chemoradiotherapy is discussed, also considering the still limited evidence and the clinical challenges arising from individualized patient management.

Finally, currently conducted clinical trials of the German Rectal Cancer Study Group are described, aiming to further individualize multimodal treatment according to risk profiles and strict MRI criteria.