Mesorectal fat area and mesorectal area affect the surgical difficulty of robotic-assisted mesorectal excision and intersphincteric resection respectively in different ways

Predictive model of the surgical difficulty of robot-assisted total mesorectal excision for rectal cancer: a multicenter, retrospective study

Rectal cancer robotic surgery is becoming more and more common, but evidence for predicting surgical difficulty is scarce. Our goal was to look at the elements that influence the complexity of robot-assisted total mesorectal excision (R-TME) in the medical care of middle and low rectal cancer as well as to establish and validate a predictive model on the basis of these factors. Within this multicenter retrospective investigation, 166 consecutive patients receiving R-TME between January 2021 and December 2022 with middle and low rectal cancer were included and categorized according to the median operation time. A nomogram was created to forecast the procedure's complexity after variables that could affect its difficulty were found using logistic regression analysis. Using R software, a total of 166 patients were randomly split into two groups: a test group (48 patients) and a training group (118 patients) at a ratio of 7 to 3. The median operation time of all patients was 207.5 min; patients whose operation time was ≥ 207.5 min were allocated to the difficult surgery group (83 patients), and patients whose operation time was < 207.5 min were allocated to the nondifficult surgery group. Multivariate analysis revealed that body mass index (BMI), the gap between the tumor and the anal verge and the posterior rectal mesenteric thickness were independent predictors of surgical duration. A clinical predictive model was created and assessed employing the above independent predictors. The results of the receiver operating characteristic (ROC) analysis revealed the adequate discriminative ability of the predictive model. Our study revealed that it is feasible to predict surgical difficulty by obtaining clinical and magnetic resonance parameters for imaging (the gap between the anal verge and the tumour, and posterior mesorectal thickness), and these predictions could be useful in making clinical decisions.

Robotic intersphincteric resection for low rectal cancer: a cumulative sum analysis for the learning curve

PURPOSE

This study aimed to assess the learning curve of robot-assisted intersphincteric resection for low rectal cancer.

METHODS

We retrospectively analyzed the clinical data of 89 patients who underwent robot-assisted intersphincteric resection. All surgeries were performed by the same group of surgeons at our institution between June 2016 and April 2021. The learning curve was evaluated using a cumulative sum analysis and the best-fit curve. The different stages of the learning curve were compared based on patient characteristics and short-term clinical outcomes to evaluate their impact on clinical efficacy.

RESULTS

The minimum number of cases required to overcome the learning curve was 47. The learning curve was divided into the learning improvement and proficiency stages. Significant differences were observed in the operation time and the number of lymph nodes between the two stages (P < 0.05), whereas no significant differences were found in intraoperative blood loss, first postoperative exhaust time, postoperative complications, 3-year progression-free survival, overall survival, and local recurrence-free survival (P > 0.05).

CONCLUSION

Robotic-assisted intersphincteric resection for low rectal cancer exhibits a learning curve that can be divided into two stages: namely, learning improvement and proficiency. Achieving proficiency requires a minimum of 47 surgical cases.

Transverse Coloplasty Pouch versus Straight Coloanal Anastomosis Following Intersphincteric Resection for Low Rectal Cancer: the Functional Benefits May Emerge After Two Years

PURPOSE

This study aimed to compare the oncological and functional outcomes following intersphincteric resection (ISR) with transverse coloplasty pouch (TCP) or straight coloanal anastomosis (SCAA) for low rectal cancer.

METHODS

A single-center retrospective analysis was performed on patients with low rectal cancer who received ISR between January 2016 and June 2021. The primary endpoint was to compare the outcomes of bowel function within 1 year, 1 to 2 years, and 2 years after ileostomy closure in patients undergoing two different bowel reconstruction procedures (TCP or SCAA). The postoperative complications and oncological results were also compared between the two groups.

RESULTS

A total of 235 patients were enrolled in this study (SCAA group: 166; TCP group: 69). There was no significant difference in complications, including grades A-C anastomotic leakage (9.6% vs 15.9%), 3-year local recurrence rates (6.1% vs 3.9%), disease-free survival (82.4%vs 83.8%), or overall survival (94.1% vs 94.7%) between the two groups. Two years after ileostomy closure, 52.7% of patients in the SCAA group were assessed as having major low anterior resection syndrome (LARS), which was significantly higher than the 25.9% of patients in the TCP group (P = 0.014), but no difference was found prior to 2 years. Similar differences were seen in Wexner scores 2 years after surgery (P = 0.032). Additionally, TCP was an independent protective factor for postoperative bowel function as measured by both the LARS (OR, 0.28; 95% CI, 0.10-0.82; p = 0.020) and Wexner scoring (OR, 0.28; 95% CI, 0.09-0.84; p = 0.023).

CONCLUSION

This study suggests that TCP is a safe technique that may decrease bowel dysfunction after ISR for low rectal cancer compared with SCAA 2 years after ileostomy closure.

Development and validation of a nomogram for predicting operating time in laparoscopic anterior resection of rectal cancer

Aims

The goal of this study is to create and verify a nomogram estimate operating time in rectal cancer (RC) patients based on clinicopathological factors and MRI/CT measurements before surgery.

Materials and Methods

The nomogram was developed in a cohort of patients who underwent laparoscopic anterior resection (L-AR) for RC. The clinicopathological and pelvis parameters were collected. Risk factors for a long operating time were determined by univariate and multivariate logistic regression analyses, and a nomogram was established with independent risk factors. The performance of the nomogram was evaluated. An independent cohort of consecutive patients served as the validation dataset.

Results

The development group recruited 159 RC patients, while 54 patients were enrolled in the validation group. Independent risk factors identified in multivariate analysis were a distance from the anal verge <5 cm (P = 0.024), the transverse diameter of the pelvic inlet (P < 0.001), mesorectal fat area (P = 0.017), and visceral fat area (P < 0.001). Then, a nomogram was built based on these four independent risk factors. The C-indexes of the nomogram in the development and validation group were 0.886 and 0.855, respectively. And values of AUC were the same with C-indexes in both groups. Besides, the calibration plots showed satisfactory consistency between actual observation and nomogram-predicted probabilities of long operating time.

Conclusions

A nomogram for predicting the risk of long operating duration in L-AR of RC was developed. And the nomogram displayed a good prediction effect and can be utilized as a tool for evaluating operating time preoperatively.

The impact of mesorectal fat area on recurrence following total mesorectal excision for lower rectal cancer

BACKGROUND

The mesorectal fat area (MFA) at the tip of the ischial spines on magnetic resonance imaging has been used to characterize mesorectal morphology. Recent studies reported that a larger MFA correlated with difficulties in rectal cancer surgery. However, the relationship between MFA and rectal cancer prognosis remains unclear. This study evaluated the impact of MFA on recurrence following robotic total mesorectal excision (TME) for rectal cancer.

METHODS

Patients who underwent robotic TME for lower rectal cancer from December 2011 to December 2016 were enrolled. Cox regression analysis was performed to determine variables associated with relapse-free survival (RFS). Patients were divided into groups based on MFA, and RFS was compared.

RESULTS

Of 230 patients, 173 (75.3%) were male. The median age was 63 years, and median MFA was 19.7 cm2. In multivariate analysis, smaller MFA (hazard ratio [HR], 0.93; 95% confidence interval [CI], 0.88-0.97; p < 0.01), p/yp stage II (HR, 3.81; 95% CI, 1.40-10.35; p < 0.01), and p/yp stage III (HR, 5.35; 95% CI, 1.88-15.27; p < 0.01) were independently associated with worse RFS. Sex, body mass index, and visceral fat area were not correlated with RFS. In the median follow-up period of 60.8 months, patients with MFA < 19.7 cm2 had a significantly lower 5-year RFS rate (72.7%) than those with MFA ≥ 19.7 cm2 (85.0%).

CONCLUSIONS

Smaller MFA was associated with worse RFS in patients undergoing robotic TME for lower rectal cancer. MFA is considered to be a prognostic factor in rectal cancer.

Role of Perirectal Fat in the Carcinogenesis and Development of Early-Onset Rectal Cancer

Purpose

The incidence of early-onset rectal cancer (EORC) has been increasing since the past decade, while its underlying cause remained unknown. This study was aimed at clarifying the relationship between perirectal fat area (PFA) and EORC. Patients and Methods. All patients with rectal cancer who received radical excision between January 2016 and December 2017 at our hospital were included. The fat series images of pelvic magnetic resonance imaging scans were obtained and PFA at the ischial spine level was calculated using the ImageJ software.

Results

A total of 303 patients were finally included and divided into two groups according to the median PFA: Group 1 (<20.2 cm², n = 151) and Group 2 (≥20.2 cm², n = 152). PFA positively correlated with body weight and body mass index. PFA increased with invasion depth, lymph node metastasis, TNM stage, tumor deposits, and vascular invasion. Patients with EORC had higher PFA than those with late-onset rectal cancer (LORC; P = 0.009). Among patients with stage I–III rectal cancers, those in Group 2 had significantly shorter disease-free survival (P = 0.010) and overall survival (P = 0.034) than those in Group 1, and PFA was an independent predictor of disease-free survival (OR: 1.683 [1.126-3.015], P = 0.035) and overall survival (OR: 1.678 [1.022-2.639], P = 0.046).

Conclusions

Patients with EORC had significantly higher PFA than those with LORC. PFA is positively correlated with T stage, N stage, TNM stage, tumor deposit, and vascular invasion and is an independent predictor of disease-free survival and overall survival. Therefore, perirectal fat may be involved in the carcinogenesis and development of EORC.