Clinical and oncological outcomes of pelvic exenteration surgery for anal squamous cell carcinoma.

AIM: Anal cancer incidence and mortality rates are rising in the United Kingdom (UK). Surgery is an important treatment modality for persistent or recurrent disease. There is a paucity of data on outcomes for patients undergoing pelvic exenteration for anal squamous cell carcinoma (SCC) for persistent or recurrent disease. The aim of this study was to investigate the outcomes for patients who were treated with pelvic exenteration for anal SCC from two high-volume, high-complexity pelvic exenteration units in the UK. METHOD: A retrospective review of prospectively maintained databases from 2011 to 2020 was undertaken. Primary endpoints included R0 resection rates, overall and disease-free survival at 2 and 5 years. RESULTS: From 2011 to 2020, 35 patients with anal SCC were selected for exenteration. An R0 resection was achieved in 26 patients (77%). Of the remaining patients, seven patients had an R1 resection and one had a R2 resection. One further patient was excluded from additional analysis as the disease was inoperable at the time of laparotomy. With a median follow-up of 19.5 months (interquartile range 7.9-53.5 months), overall survival was 50% (17/34). Patients with an R1/2 resection had a significantly poorer overall survival [0.27 (0.09-0.76), p = 0.021] than those patients in whom R0 resection was achieved. Disease-free survival was 38.2% (13/34) and an R1/R2 resection was associated with a significantly reduced disease-free survival [0.12 (0.04-0.36), p < 0.001]. CONCLUSION: Complete R0 resection for recurrent or persistent anal SCC is possible in the majority of patients and improves overall and disease-free survival compared with R1/R2 resection.

Outcomes associated with the use of a new powered circular stapler for left-sided colorectal reconstructions: a propensity score matching-adjusted indirect comparison with manual circular staplers.

BACKGROUND: This was a retrospective, matching-adjusted indirect comparison of clinical outcomes between patients from a single-arm trial of the ECHELON CIRCULAR™ Powered Stapler (ECP) and those from a historical cohort of patients who underwent left-sided colorectal resection using conventional manual circular staplers, extracted from the Premier Healthcare Database. METHODS: Patients in the ECP trial cohort were propensity score matched to those in the historical cohort through nearest neighbor matching. Outcomes included 30-day readmission rates; length of stay (LOS) for the index admission; rates of anastomotic leak, pelvic abscess, ileus/small bowel obstruction, infection, bleeding, and stoma creation. RESULTS: The study included 168 patients in the ECP trial cohort and 4544 patients in the historical cohort; 165 ECP trial patients were matched to 1348 historical cohort patients. After matching, conversions were more prevalent in the historical cohort than the ECP trial cohort (4.2% ECP vs. 10.2% historical, p = 0.001). Relative to the historical cohort, the ECP trial cohort had statistically significant lower rates of 30-day inpatient readmission (6.1% vs. 10.8%, p = 0.019), anastomotic leak (1.8% vs. 6.9%, p < 0.001), ileus/small bowel obstruction (4.8% vs. 14.7%, p < 0.001), infection (1.8% vs. 5.7%, p = 0.001), and bleeding (1.8% vs. 9.2%, p < 0.001) during the index admission or within 30 days thereafter. No statistically significant differences in rates of pelvic abscess, stoma creation, or LOS were found between the two cohorts. Three sensitivity analyses to address the difference in conversion rates yielded largely consistent results, with loss of statistical significance for inpatient admission in some cases. This study is limited by its potential for differences in unmeasurable factors between the ECP trial and historical cohorts. CONCLUSIONS: In this study, the ECP trial cohort had lower incidence proportions of several surgical complications as compared with the historical cohort. Further controlled prospective clinical studies are needed to confirm the validity of this finding.

S1 Sacrectomy for Re-recurrent Rectal Cancer: Our Experience with Reconstruction Using an Expandable Vertebral Body Replacement Device.

INTRODUCTION: R0 resection is achieved by high sacrectomy for local recurrence of colorectal cancer, but significant rates of perioperative complications and long-term patient morbidity are associated with this procedure. In this report, we outline our unique experience of using an expandable cage for vertebral body reconstruction following S1 sacrectomy in a 66-year-old patient with re-recurrent rectal cancer. We aim to highlight several key steps, with a view to improving postoperative outcomes. TECHNIQUE: A midline laparotomy was performed with the patient in supine Lloyd-Davies position, demonstrating recurrence of tumor at the S1 vertebral body. Subtotal vertebral body excision of S1 with sparing of the posterior wall and ventral foramina was completed by using an ultrasonic bone aspirator. Reconstruction was performed using an expandable corpectomy spacer system. The system was assembled and expanded in situ to optimally bridge the corpectomy. The device was secured into the L5 and S2 vertebrae by means of angled end plate screws superiorly and inferiorly. Bone grafts were positioned adjacent to the implant after this. RESULTS: Total operating time was 266 minutes with 350 mL of intraoperative blood loss. There were no immediate postoperative complications. The patient did not report any back pain at the time of discharge, and no neurological deficit was reported or identified. Postoperative CT scan showed excellent vertebral alignment and preservation of S1 height. CONCLUSION: We conclude that high sacrectomy with an expandable metal cage is feasible in the context of re-recurrent rectal cancer when consideration is given to the method of osteotomy and vertebral body replacement.

The Outcomes and Patterns of Treatment Failure After Surgery for Locally Recurrent Rectal Cancer.

OBJECTIVE: To assess the outcomes and patterns of treatment failure of patients who underwent pelvic exenteration surgery for recurrent rectal cancer. BACKGROUND: Despite advances in the management of rectal cancer, local recurrence still occurs. For appropriately selected patients, pelvic exenteration surgery can achieve long-term disease control. METHODS: Prospectively maintained databases of 5 high volume institutions for pelvic exenteration surgery were reviewed and data combined. We assessed the combined endpoints of overall 5-year survival, cancer-specific 5-year mortality, local recurrence, and the development of metastatic disease. RESULTS: Five hundred thirty-three patients who had undergone surgery for locally recurrent rectal cancer were identified. Five-year cancer-specific survival for patients with a complete (R0) resection is 44%, which was achieved in 59% of patients. For those with R1 and R2 resections, the 5-year survival was 26% and 10%, respectively. Radical resection required sacrectomy in 170 patients (32%), and total cystectomy in 105 patients (20%). Treatment failure included local recurrence alone in 75 patients (14%) and systemic metastases with or without local recurrence in 226 patients (42%). Chemoradiotherapy before exenteration was associated with a significant (P < 0.05) improvement in overall 5-year cancer-specific survival for those patients with an R0 resection. Postoperative chemotherapy did not alter outcomes. CONCLUSIONS: R0 resection of the pelvic recurrence is the most significant factor affecting overall and disease-free survival. The surgery is complex and often highly morbid, and where possible patients should be given perioperative chemoradiotherapy. Further investigations are required to determine the role of adjuvant chemotherapy.

Incidence and significance of postoperative complications occurring between discharge and 30 days: a prospective cohort study.

BACKGROUND: Accurate documentation of complications is fundamental to clinical audit and research. While it is established that accurate diagnosis of surgical site infection (SSI) requires follow-up for 30 days; for other complications, there are minimal data quantifying their importance between discharge and 30 days. METHODS: In this prospective cohort study, inpatients undergoing general or vascular surgery were reviewed daily for complications by the medical team and a research fellow. A standardized telephone questionnaire was performed 30 days following surgery. All complications were documented and classified according to severity. RESULTS: A total of 237 of 388 patients who completed the telephone survey developed a complication, including 77 who developed a complication for the first time after discharge from hospital. Overall 135 (33%) of a total of 405 complications were identified after discharge. These complications included 36 of 63 (57%) SSI, 6 of 12 small bowel obstructions, and three of four major thromboembolic events and a number of space SSI, urinary infections, functional gastrointestinal problems, and pain management problems. Cardiac, respiratory, and neurologic complications were mainly diagnosed in hospital. Of the 135 "postdischarge" complications, 89 were managed in the community and 46 (34%) resulted in admission to hospital, including seven which required a major intervention. There was one death. CONCLUSIONS: One-third of complications occurred after discharge, and one-third of these resulted in readmission to hospital. Research and audit based on inpatient data alone significantly underestimates morbidity rates. Discharge planning should include contingency plans for managing problems commonly diagnosed after discharge form hospital.

Systematic review of health-related quality of life issues in locally recurrent rectal cancer.

The standardization of surgical techniques supplemented with appropriate neoadjuvant chemoradiation has led to the decline in local recurrence rates of rectal cancer (LRRC) from 25-50% to 5-10%. The outcomes reported for surgical intervention in LRRC is encouraging, however, a number of controversies exist especially in the ultra-advanced and palliative setting. Incorporating health-related quality of life (HRQoL) outcomes in this field could supplement traditional clinical endpoints in assessing the effectiveness of surgical intervention in this cohort. This review aimed to identify the HRQOL themes that might be relevant to patients with LRRC. A systematic review was undertaken to identify all studies reporting HRQoL in LRRC. Each study was evaluated with regards to its design and statistical methodology. A meta-synthesis of qualitative and quantitative studies was undertaken to identify relevant HRQoL themes. A total of 14 studies were identified, with 501 patients, with 80% of patients undergoing surgery. HRQoL was the primary endpoint in eight studies. Eight themes were identified: physical, psychological and social impact, symptoms, financial and occupational impact, relationships with others, communication with healthcare professionals and sexual function. The impact on HRQoL is multifactorial and wide ranging, with a number of issues identified that are not included in current measures. These issues must be incorporated into the assessment of HRQoL in LRRC through the development of a validated, disease-specific tool.

Short-term outcomes of health-related quality of life in patients with locally recurrent rectal cancer: multicentre, international, cross-sectional cohort study.

BACKGROUND: Overall survival rates for locally recurrent rectal cancer (LRRC) continue to improve but the evidence concerning health-related quality of life (HrQoL) remains limited. The aim of this study was to describe the short-term HrQoL differences between patients undergoing surgical and palliative treatments for LRRC. METHODS: An international, cross-sectional, observational study was undertaken at five centres across the UK and Australia. HrQoL in LRRC patients was assessed using the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-CR29 and functional assessment of cancer therapy - colorectal (FACT-C) questionnaires and subgroups (curative versus palliative) were compared. Secondary analyses included the comparison of HrQoL according to the margin status, location of disease and type of treatment. Scores were interpreted using minimal clinically important differences (MCID) and Cohen effect size (ES). RESULTS: Out of 350 eligible patients, a total of 95 patients participated, 74.0 (78.0 per cent) treated with curative intent and 21.0 (22.0 per cent) with palliative intent. Median time between LRRC diagnosis and HrQoL assessments was 4 months. Higher overall FACT-C scores denoting better HrQoL were observed in patients undergoing curative treatment, demonstrating a MCID with a mean difference of 18.5 (P < 0.001) and an ES of 0.6. Patients undergoing surgery had higher scores denoting a higher burden of symptoms for the EORTC CR29 domains of urinary frequency (P < 0.001, ES 0.3) and frequency of defaecation (P < 0.001, ES 0.4). Higher overall FACT-C scores were observed in patients who underwent an R0 resection versus an R1 resection (P = 0.051, ES 0.6). EORTC CR29 scores identified worse body image in patients with posterior/central disease (P = 0.021). Patients undergoing palliative chemoradiation reported worse HrQoL scores with a higher symptom burden on the frequency of defaecation scale compared with palliative chemotherapy (P = 0.041). CONCLUSION: Several differences in short-term HrQoL outcomes between patients undergoing curative and palliative treatment for LRRC were documented. Patients undergoing curative surgery reported better overall HrQoL and a higher burden of pelvic symptoms.

Development and validation of a patient reported outcome measure for health-related quality of life for locally recurrent rectal cancer: a multicentre, three-phase, mixed-methods, cohort study.

Background: Locally recurrent rectal cancer (LRRC) occurs in 5-10% of patients following previous treatment of rectal cancer. It has a significant impact on patients' overall health-related quality of life (HrQoL). Major advances in surgical treatments have led to improved survival outcomes. However, due to the lack of disease-specific, validated patient-reported outcome measure (PROM), HrQoL, is variably assessed. The aim of this study is to develop a disease-specific, psychometrically robust, and validated PROM for use in LRRC. Methods: A multicentre, three phase, mixed-methods, observational study was performed across five centres in the UK and Australia. Adult patients (>18 years old) with an existing or previously treated LRRC within the last 2 years were eligible to participate. Patients completed the proposed LRRC-QoL, EORTC QLQ-CR29, and FACT-C questionnaires. Scale structure was analysed using multi-trait scaling analysis and exploratory factor analysis, reliability was assessed using Cronbach's and the intra-class coefficient, convergent validity was assessed using Pearson's correlation, and known-groups comparison was assessed using the student t-test or ANOVA. Findings: Between 01/03/2015 and 31/12/2019, 117 patients with a diagnosis of LRRC were recruited. The final scale structure of the LRRC-QoL consisted of nine multi-item scales (healthcare services, psychological impact, pain, urostomy-related symptoms, lower limb symptoms, stoma, sexual function, sexual interest, and urinary symptoms) and three single items. Cronbach's Alpha and Intraclass correlation values of >0.7 across the majority of scales supported overall reliability. Convergent validity was demonstrated between LRRC-QoL Pain Scale and FACT-C Physical Well Being scale (r = 0.528, p < 0.001), LRRC-QoL Psychological Impact scale with EORTC QLQ CR29 Body Image (r = 0.680, p < 0.001) and the FACT-C Emotional Well Being scale (r = 0.326, p < 0.001), and LRRC-QoL Urinary Symptoms scale with EORTC QLQ-CR29 Urinary Frequency scale (r = 0.310, p < 0.001). Known-groups validity was demonstrated for gender, disease location, treatment intent, and re-recurrent disease. Interpretation: The LRRC-QoL has demonstrated robust psychometric properties and can be used in clinical and academic practice. Funding: None.

The management of retrorectal tumours: tertiary centre retrospective study.

AIM: Tumours of the retrorectal space are uncommon, pathologically heterogeneous, and difficult to diagnose, with ongoing controversy over their surgical management. The aim of this study was to evaluate the surgical management of a consecutive series of patients who had undergone excision of primary retrorectal tumours (PRRTs) at a tertiary referral centre. METHOD: Patients were identified from a prospectively maintained database between 1 March 2001 and 1 August 2021. Electronic patient records were reviewed for demographics, preoperative imaging, operative details, histology, and follow-up. A chi-squared test was used to assess the statistical significance of findings. RESULTS: A total of 144 patients were included in the study. Of these, 103 patients were female (71.5 per cent), 46 patients (31.9 per cent) presented incidentally, and 99 of the patients had tumours located below S3 (68.7 per cent). Overall, 76 patients underwent a transperineal approach (52.7 per cent) with the most common findings of a benign tailgut cyst occurring in 59 (40.9 per cent) of cases. Preoperative MRI predicted urovascular and pelvic sidewall involvement assessed intraoperatively with a sensitivity of 83.3 and 90 per cent and a specificity of 98.1 and 98 per cent respectively. Risk of malignancy in solid tumours was 31.4 versus 8.8 per cent in cystic tumours (relative risk 3.5, 95 per cent c.i. 1.6 to 7.6, P < 0.001). Major complications (Clavien-Dindo grade III and above) occurred in eight patients (5.6 per cent) and all-cause long-term mortality was 4.8 per cent (seven patients). DISCUSSION: PRRTs can be safely excised with minimal complications in specialized centres by surgical teams with the relevant expertise. This study questions the conservative management of cystic tumours and given the risk of solid tumour malignancy, supports surgical management.

Recruiting to surgical trials in the emergency setting: using a mixed methods study to understand clinician and patient perspectives.

BACKGROUND: Undertaking randomized clinical trials (RCTs) in emergency surgical settings is associated with methodological and practical challenges. This study explored patients' and clinicians' perspectives associated with the conduct of an RCT comparing laparoscopic and open colorectal surgery in the acute setting. METHODS: All eligible patients screened and enrolled for the 'Laparoscopic versus open colorectal surgery in the acute setting (LaCeS)' multicentre, randomized clinical feasibility trial in five UK NHS Trusts were invited to respond to a survey. Patients and healthcare professionals were also invited to take part in semi-structured interviews. Survey and interviews explored the acceptability of the feasibility trial. Interviews were audio recorded, transcribed verbatim, and analysed using thematic analysis. Survey data were analysed descriptively to assess patient views of the trial and intervention. RESULTS: Out of 72 patients enrolled for the LaCeS RCT, survey data were collected from 28 patients (38.9 per cent), and interviews were conducted with 16 patients and 14 healthcare professionals. Thirteen out of 28 patients (46 per cent) had treatment preferences but these were not strong enough to deter participation. Twelve of the patients interviewed believed that their surgeon preferred laparoscopic surgery, but this did not deter them from participating in the trial. Half of the surgeons interviewed expressed the view that laparoscopic surgery was of benefit in this setting, but recognized that the need for research evidence outweighed their personal treatment preferences. Eight of the 14 recruiters reported that the emergency setting affected recruitment, especially in centres with fewer recruiting surgeons. Interviewees reported that recruitment was helped significantly by using surgical trainees to consent patients. CONCLUSION: This study identified specific challenges for the LaCeS trial design to address and adds significant insights to our understanding of recruiting to emergency surgical trials more broadly.

Increased local recurrence and reduced survival from colorectal cancer following anastomotic leak: systematic review and meta-analysis.

OBJECTIVE: To examine the long-term oncological impact of anastomotic leakage (AL) after restorative surgery for colorectal cancer using meta-analytical methods. Outcomes evaluated were local recurrence, distant recurrence, and survival. BACKGROUND: Recurrence after potentially curative surgery for colorectal cancer remains a significant clinical problem and has a poor prognosis. AL may be a risk factor for disease recurrence, however available studies have been conflicting. A meta-analysis was conducted to investigate the impact of AL on disease recurrence and long-term survival. METHODS: Studies published between 1965 and 2009 evaluating the long-term oncological impact of AL were identified by an electronic literature search. Outcomes evaluated included local recurrence, distant recurrence, and cancer specific survival. Meta-analysis was performed using the DerSimonian-Laird random-effects model to compute odds ratio and 95% confidence intervals. Study heterogeneity was evaluated using Q statistics and I and publication bias assessed with funnel plots and Egger's test. RESULTS: Twenty-one studies comprising 13 prospective nonrandomized studies, 1 prospective randomized, and 7 retrospective studies met the inclusion criteria, yielding a total of 21,902 patients. For rectal anastomoses, the odd ratios (OR) of developing a local recurrence when there was AL was 2.05 (95% CI = 1.51-2.8; P = 0.0001). For studies describing both colon and rectal anastomoses, the OR of local recurrence when there was an AL was 2.9 (95% CI = 1.78-4.71; P < 0.001). The OR of developing a distant recurrence after AL was 1.38 (95% CI = 0.96-1.99; P = 0.083). Long term cancer specific mortality was significantly higher after AL with an OR of 1.75 (95% CI = 1.47-2.1; P = 0.0001). CONCLUSIONS: AL has a negative prognostic impact on local recurrence after restorative resection of rectal cancer. A significant association between colorectal AL and reduced long-term cancer specific survival was also noted. No association between AL and distant recurrence was found.

Clinical algorithms for the surgical management of locally recurrent rectal cancer.

PURPOSE: Advances in surgical practice have helped expand the options for patients with locally recurrent rectal cancer through improvements in reconstructive options, management of operative complications, addition of intraoperative adjuvant therapies, and postoperative care. This review outlines the presentation and management of patients with locally recurrent rectal cancer, and it describes easy-to-apply clinical algorithms to aid management. METHODS: The electronic literature was searched for studies reporting outcomes for locally recurrent rectal cancer limited to the English language. RESULTS: Prospective and retrospective case series and single-center experiences were identified. A total of 106 articles were selected for full-text review of which 82 fulfilled the inclusion criteria. No randomized studies were identified. We found that multimodality treatment of locally recurrent rectal cancer can improve 5-year survival from 0% to over 40%, and selected patients may survive up to 10 years. A mixture of imaging modalities is used in patient selection for surgery. An R0 resection is consistently a favorable prognostic factor. R1 resection and surgery in the setting of oligometastases compare favorably with nonoperative palliation. Although mortality figures remain low, morbidity is significant and mostly wound related. CONCLUSIONS: Improvements in radiological imaging modalities and technical improvements in surgical and reconstructive options have facilitated more accurate staging, better selection of patients for surgery, reduced morbidity and mortality, and higher R0 resections. Optimal management is in specialist units with a multidisciplinary approach with the use of multimodal therapy.

Assessment of a circular powered stapler for creation of anastomosis in left-sided colorectal surgery: A prospective cohort study.

BACKGROUND: Circular staplers perform a critical function for creation of anastomoses in colorectal surgeries. Powered stapling systems allow for reduced force required by surgeons to fire the device and may provide advantages for creating a secure anastomosis. The objective of this study was to evaluate the clinical performance of a novel circular powered stapler in a post-market setting, during left-sided colectomy procedures. MATERIALS AND METHODS: Consecutive subjects underwent left-sided colorectal resections that included anastomosis performed with the ECHELON CIRCULAR™ Powered Stapler (ECP). The primary endpoint was the frequency in which a stapler performance issue was observed. Secondary endpoints included evaluation of ease of use of the device via a surgeon satisfaction questionnaire, and monitoring/recording of procedure-related adverse events (AEs). RESULTS: A total of 168 anastomoses were performed with the ECP. Surgical approaches included robotic-assisted (n = 74, 44.0%), laparoscopic (n = 71, 42.3%), open (n = 20, 11.9%), and hand-assisted minimally invasive (n = 3, 1.8%) procedures. There were 22 occurrences of device performance issues in 20 (11.9%) subjects during surgery. No positive intraoperative leak tests were observed, and only 1 issue was related to a procedure-related AE or surgical complication, which was an instance of incomplete surgical donut necessitating re-anastomosis. Postoperative anastomotic leaks were experienced in 4 (2.4%) subjects. Clavien-Dindo classification of all AEs indicated that 92.0% were Grades I or II. Participating surgeons rated the ECP as easier to use compared to previously used manual circular staplers in 85.7% of procedures. CONCLUSION: The circular powered stapler exhibited few clinically relevant performance issues, an overall favorable safety profile, and ease of use for creation of left-sided colon anastomoses.

Assessment of the efficacy of the rectovaginal button fistula plug for the treatment of ileal pouch-vaginal and rectovaginal fistulas.

BACKGROUND: The treatment of rectovaginal and ileal pouch-vaginal fistulas remains a challenging problem for the colorectal surgeon. The aim of this study was to assess the short-term efficacy of the new Surgisis Biodesign rectovaginal button fistula plug in patients with such fistulas. METHODS: Between May 2008 and September 2008, patients with confirmed rectovaginal and ileal pouch-vaginal fistulas with backgrounds of inflammatory bowel disease were treated with the button fistula plug. The fistulas were assessed by magnetic resonance imaging and/or examination under anesthesia before the procedure. RESULTS: Twelve patients with a median age of 36 (range, 29-42) years underwent a total of 20 plug insertions. Five patients had confirmed rectovaginal fistulas and seven patients had ileal pouch-vaginal fistulas. At a median follow-up of 15 (interquartile range, 10-21) weeks, 7 of 12 patients (58%) had been treated successfully. Seven of the 20 plugs that were inserted (35%) were successful. This equates to the successful treatment of three of five (60%) of the rectovaginal fistulas, and four of seven (57%) of the ileal pouch-vaginal fistulas. Of the six patients who initially failed, a repeat procedure was performed of which one was successful. Two patients underwent a third repeat procedure, which was again unsuccessful in both cases. The success rate of these eight repeat plug insertions was therefore 12.5%. All plug failures were the result of dislodgement of the plug. There was no morbidity in our series. CONCLUSIONS: The new button fistula plug successfully treated 7 of 12 (58%) rectovaginal and ileal pouch-vaginal fistulas.

Morphology of the mesorectum in patients with primary rectal cancer.

PURPOSE: The size and contents of the pelvis differ between the genders, and this may affect mesorectal size and shape. The aim of this prospective pilot study was to examine radiologically the applied anatomy of the mesorectum. METHODS: Fifty-eight patients (35 male, 23 female) with primary rectal cancer who had suitable high-resolution staging pelvic magnetic resonance images between November 2002 and July 2004 were studied. Ten variables of mesorectal morphology were measured on axial images at the ischial spines. The associations between morphologic variables and gender and body mass index were examined. RESULTS: Compared with female patients, male patients had a larger area of overall mesorectal package (3,776 mm2 vs. 2,772 mm2, P = 0.001), larger area of mesorectal fat (2,562 mm2 vs. 1,842 mm2, P = 0.001), and higher ratio of anteroposterior to transverse diameter of the mesorectal package (0.82 vs. 0.56, P < 0.001). The anterior mesorectal fat buffer was significantly thinner in females than in males (2.9 mm vs. 7.8 mm, P < 0.001). Mesorectal fat area was greater in males with a body mass index >25 than with a body mass index <25. CONCLUSIONS: Males have a larger overall mesorectal package compared with females, mainly caused by mesorectal fat. The anterior mesorectal fat is significantly thinner in females than in males. Such morphologic differences may affect resection margin status.