Prehabilitation in rectal surgery: a narrative review.

AIM: Neoadjuvant chemotherapy (NACRT) can make decompensated patients more vulnerable prior to rectal surgery. Prehabilitation is an intervention which enhances functional capacity to withstand the stress of surgery. The aim of this review was to evaluate the impact of prehabilitation for patients undergoing rectal surgery on physical fitness and clinical outcomes and to establish feasibility of prehabilitation. METHODS: An analysis of the literature was conducted of PubMed, the Cochrane Library, MEDLINE, EMBASE and ScienceDirect. Articles were initially included based on their title and abstracts reviewed. Full-text copies of those selected were obtained for confirmation of inclusion. RESULTS: Eight studies were included. Heterogenicity was observed in the structure of exercise programmes. Improvements in physical fitness were observed in six studies. One study demonstrated a statistically significant improvement in quality of life. The prehabilitation programmes were shown to be feasible, with high completion rates. No adverse events were reported. There was limited data regarding the impact of prehabilitation on postoperative outcomes. CONCLUSION: Current evidence on prehabilitation in rectal surgery has considerable heterogenicity in both structure of programmes and outcome measures. Standardisation is required for future evaluation of the impact on outcomes. A trimodal approach of exercise, nutritional and psychological interventions has been employed in similar programmes, and should be used in rectal surgery. The intervention should be tailored to the patient and environment. This review highlights the benefits, safety and feasibility of prehabilitation and provides a platform for consensus-building for international trials.

Muir-Torre syndrome: a case of unusual coexisting genetic mutations.

Patients with Muir-Torre syndrome (MTS) commonly have germline mismatch repair mutations in MLH1, MSH2 or MSH6, with a strong predominance in MSH2. A subset of approximately one-third of patients will instead have an autosomal recessive base excision repair mutation in MUTYH called MUTYH polyposis. To the best of our knowledge, this is the first report of coexisting germline MSH2 and MUTYH mutations in a patient with MTS.

Oncological outcomes of laparoscopic versus open rectal cancer resections: meta-analysis of randomized clinical trials.

BACKGROUND: The role of laparoscopic rectal cancer surgery has been questioned owing to conflicting reports on pathological outcomes from recent RCTs. However, it is unclear whether these pathological markers and the surgical approach have an impact on oncological outcomes. This study assessed oncological outcomes of laparoscopic and open rectal cancer resections. METHODS: A meta-analysis of RCTs was performed. Primary endpoints included oncological outcomes (disease-free survival (DFS), overall survival (OS), local recurrence). Secondary endpoints included surrogate markers for the quality of surgical resection. RESULTS: Twelve RCTs including 3744 patients (2133 laparoscopic, 1611 open) were included. There was no significant difference in OS (hazard ratio (HR) 0.87, 95 per cent c.i. 0.73 to 1.04; P = 0.12; I2 = 0 per cent) and DFS (HR 0.95, 0.81 to 1.11; P = 0.52; I2 = 0 per cent) between laparoscopic and open rectal resections. There was no significant difference in locoregional (odds ratio (OR) 1.03, 95 per cent c.i. 0.72 to 1.48; P = 0.86; I2 = 0 per cent) or distant (OR 0.87, 0.70 to 1.08; P = 0.20; I2 = 7 per cent) recurrence between the groups. Achieving a successful composite score (intact mesorectal excision, clear circumferential resection margin and distal margin) was significantly associated with improved DFS (OR 0.55, 0.33 to 0.74; P < 0.001; I2 = 0 per cent). An intact or acceptable mesorectal excision (intact mesorectal excision with or without superficial defects) had no impact on DFS. Finally, a positive CRM was associated with worse DFS. CONCLUSION: Well performed surgery (laparoscopic or open) achieves excellent oncological outcomes with very little difference between the two modalities. The advantage and benefit of minimally invasive surgery should be assessed on an individual basis.

An introduction to cryo-FIB-SEM cross-sectioning of frozen, hydrated Life Science samples.

The introduction of cryo-techniques to the focused ion-beam scanning electron microscope (FIB-SEM) has brought new opportunities to study frozen, hydrated samples from the field of Life Sciences. Cryo-techniques have long been employed in electron microscopy. Thin electron transparent sections are produced by cryo-ultramicrotomy for observation in a cryo-transmission electron microscope (TEM). Cryo-TEM is presently reaching the imaging of macromolecular structures. In parallel, cryo-fractured surfaces from bulk materials have been investigated by cryo-SEM. Both cryo-TEM and cryo-SEM have provided a wealth of information, despite being 2D techniques. Cryo-TEM tomography does provide 3D information, but the thickness of the volume has a maximum of 200-300 nm, which limits the 3D information within the context of specific structures. FIB-milling enables imaging additional planes by creating cross-sections (e.g. cross-sectioning or site-specific X-sectioning) perpendicular to the cryo-fracture surface, thus adding a third imaging dimension to the cryo-SEM. This paper discusses how to produce suitable cryo-FIB-SEM cross-section results from frozen, hydrated Life Science samples with emphasis on 'common knowledge' and reoccurring observations. LAY DESCRIPTION: Life Sciences studies life down to the smallest details. Visualising the smallest details requires electron microscopy, which utilises high-vacuum chambers. One method to maintain the integrity of Life Sciences samples under vacuum conditions is freezing. Frozen samples can remain in a suspended state. As a result, research can be carried out without having to change the chemistry or internal physical structure of the samples. Two types of electron microscopes equipped with cryo-sample handling facilities are used to investigate samples: The scanning electron microscope (SEM) which investigates surfaces and the transmission electron microscope (TEM) which investigates thin electron transparent sections (called lamellae). A third method of investigation combines a SEM with a focused ion beam (FIB) to form a cryo-FIB-SEM, which is the basis of this paper. The electron beam images the cryo-sample surface while the ion beam mills into the surface to expose the interior of the sample. The latter is called cross-sectioning and the result provides a way of investigating the 3rd dimension of the sample. This paper looks at the making of cross-sections in this manner originating from knowledge and experience gained with this technique over many years. This information is meant for newcomers, and experienced researchers in cryo-microscopy alike.

Cryo-FIB preparation of whole cells and tissue for cryo-TEM: use of high-pressure frozen specimens in tubes and planchets.

The desire to study macromolecular complexes within their cellular context requires the ability to produce thin samples suitable for cryo-TEM (cryo-transmission electron microscope) investigations. In this paper, we discuss two similar approaches, which were developed independently in Utrecht (the Netherlands) and Albany (USA). The methods are particularly suitable for both tissue samples and cell suspensions prepared by a high-pressure freezer (HPF). The workflows are explained with particular attention to potential pitfalls, while underlying principles are highlighted ('why to do so'). Although both workflows function with a high success rate, full execution requires considerable experience and remains demanding. In addition, throughput is low. We hope to encourage other research groups worldwide to take on the challenge of improving the HPF- cryo-FIB-SEM - cryo-TEM workflow. We discuss a number of suggestions to this end. LAY DESCRIPTION: Life is ultimately dictated by the interaction of molecules in our bodies. Highly complex equipment is being used and further developed to study these interactions. The present paper describes methods to prepare small, very thin lamellae (area of 5×5 µm2 , thickness 50-300 nm) of a cell to be studied in a cryo-transmission electron microscope (cryo-TEM). Special care must be taken to preserve the natural state of molecules in their natural environment. In the case of cryo-TEM, the samples must be frozen and kept frozen to be compatible with the vacuum conditions in the microscope. The frozen condition imposes technical challenges which are addressed. Two approaches to obtain the thin lamellae are described. Both make use of a focused ion beam (FIB) microscope. The FIB allows removal of material with nanometre precision by focusing a beam of ionised atoms (gallium ions) onto the sample. Careful control of the FIB allows cutting out of the required thin lamellae. In both strategies, the thin lamellae remain attached to the original sample, and the ensemble of sample with section and sample holder is transported from the FIB microscope to the TEM while being kept frozen.

Prostaglandin E2 receptors and their role in gastrointestinal motility - Potential therapeutic targets.

Prostaglandin E2 (PGE2) is found throughout the gastrointestinal tract in a diverse variety of functions and roles. The recent discovery of four PGE2 receptor subtypes in intestinal muscle layers as well as in the enteric plexus has led to much interest in the study of their roles in gut motility. Gut dysmotility has been implicated in functional disease processes including irritable bowel syndrome (IBS) and slow transit constipation, and lubiprostone, a PGE2 derivative, has recently been licensed to treat both conditions. The diversity of actions of PGE2 in the intestinal tract is attributed to its differing effects on its downstream receptor types, as well as their varied distribution in the gut, in both health and disease. This review aims to identify the role and distribution of PGE2 receptors in the intestinal tract, and aims to elucidate their distinct role in gut motor function, with a specific focus on functional intestinal pathologies.

Lateral pelvic lymphadenectomy for low rectal cancer: a META-analysis of recurrence rates.

BACKGROUND: Locoregional recurrence (LR) remains a problem for patients with lower rectal cancer despite standardized surgery and improved neoadjuvant treatment regimens. Lateral pelvic lymph node dissection (LPLND) has been routine practice for some time in the Orient/East, but other regions have concerns about morbidity. As perioperative care and surgical approaches are refined, this has been revisited for selected patients. The question as to whether LPLND improves oncological outcomes was explored here. METHODS: A systematic review of patients who underwent TME with or without LPLND from 2000 to 2020 was performed. The primary endpoint was the rate of LR between the two groups. RESULTS: Seven papers met the predefined search criteria in which 2000 patients underwent TME alone, while 1563 patients had TME and LPLND. The rate of LR was marginally higher with TME alone when compared with TME plus LPLND, but this result was not statistically significant (9.8 vs 9.4%, odds ratio 0.75, 95% CI 0.41-1.38, *p = 0.35). In addition, four studies reported on distant recurrence rates, with TME and LPLND showing a slight reduction in overall rates (27.3 vs 29.9%, respectively, OR 0.65, 95% CI 0.45-0.92, *p = 0.02). CONCLUSION: The addition of LPLND to TME is not associated with a significantly lower risk of LR in patients who undergo surgery for lower rectal cancer.

[Successful deployment of a percutaneous aortic valve in a patient with a mitral prosthesis. Risks and technical considerations]. / Implante de válvula aórtica percutánea en paciente con prótesis mitral previa: riesgos y consideraciones técnicas.

The deployment of a percutaneous aortic valve is challenging in patients with a mitral prosthesis. The risk of prosthetic deformation, embolization or dysfunction is higher in this group of patients, which requires a series of technical considerations. We report a successful implantation of an Evolut Pro # 29 self-expanding valve in a 67-year-old female with a previous Starr-Edwards caged-ball mitral prosthesis.

Clinicopathological features and oncological outcomes of patients with young-onset rectal cancer.

BACKGROUND: The incidence of rectal cancer among adults aged less than 50 years is rising. Survival data are limited and conflicting, and the oncological benefit of standard neoadjuvant and adjuvant therapies is unclear. METHODS: Disease-specific outcomes of patients diagnosed with rectal cancer undergoing surgical resection with curative intent between 2006 and 2016 were analysed. RESULTS: A total of 797 patients with rectal cancer were identified, of whom 685 had surgery with curative intent. Seventy patients were younger than 50 years and 615 were aged 50 years or more. Clinical stage did not differ between the two age groups. Patients aged less than 50 years were more likely to have microsatellite instability (9 versus 1·6 per cent; P = 0·003) and Lynch syndrome (7 versus 0 per cent; P < 0·001). Younger patients were also more likely to receive neoadjuvant chemoradiotherapy (67 versus 53·3 per cent; P = 0·003) and adjuvant chemotherapy (41 versus 24·2 per cent; P = 0·006). Five-year overall survival was better in those under 50 years old (80 versus 72 per cent; P = 0·013). The 5-year disease-free survival rate was 81 per cent in both age groups (P = 0·711). There were no significant differences in the development of locoregional recurrence or distant metastases. CONCLUSION: Despite accessing more treatment, young patients have disease-specific outcomes comparable to those of their older counterparts.

ANTECEDENTES: La incidencia de cáncer de recto entre adultos menores de 50 años está aumentando. Los datos de supervivencia son limitados y contradictorios, y el beneficio oncológico de los tratamientos neoadyuvantes y adyuvantes estándares no está claro. MÉTODOS: Se analizaron los resultados específicos relacionados con la enfermedad en pacientes diagnosticados de cáncer de recto operados con intención curativa entre 2006 y 2016. RESULTADOS: Se identificaron un total de 797 pacientes con cáncer de recto, de los cuales 685 fueron intervenidos quirúrgicamente con intención curativa. Setenta tenían menos de 50 años y 615 tenían 50 años o más. No hubo diferencias en el estadio clínico entre los dos grupos de edad. Los pacientes menores de 50 años tenían más probabilidades de tener inestabilidad de microsatélites (9% versus 2%, P = 0,003) y síndrome de Lynch (7% versus 0%, P ≤ 0,001). La supervivencia global a los 5 años fue mayor en los pacientes de menos de 50 años (80% y 72%; P = 0,013). La supervivencia libre de enfermedad a los 5 años fue del 81% en ambos grupos de edad (P = 0,711). No hubo diferencias significativas en el desarrollo de recidiva locorregional o metástasis a distancia. Los pacientes más jóvenes tenían más probabilidades de recibir quimiorradioterapia neoadyuvante (67% versus 53%, P = 0,003) y quimioterapia adyuvante (41% versus 24%, P = 0,006). CONCLUSIÓN: A pesar de tener acceso a más tratamientos, los pacientes jóvenes han presentado resultados específicos relacionados con la enfermedad comparables a sus homólogos de mayor edad.

The influence of the gastrointestinal microbiome on colorectal metastasis: a narrative review.

INTRODUCTION: The gastrointestinal microbiome has been suggested to contribute to the development of both primary and secondary colorectal cancer. Despite advances in understanding the prognostic and predictive value of clinico-pathological parameters, the underlying mechanisms that result in progression to metastatic disease have yet to be defined. The metastatic cascade involves a number of sequential steps, including detachment of tumour cells from the primary site, intravasation and dissemination within the circulatory and lymphatic systems, with extravasation and proliferation at a secondary site. OBJECTIVE: An analysis of the literature relating to the gastrointestinal microbiome and its role in colorectal metastasis was conducted. This review aims to examine the current evidence supporting a role for the microbiome in colorectal metastasis and to describe the mechanisms by which it may contribute to metastatic progression. CONCLUSION: The invasive pathways utilized by bacteria and how they may be manipulated by tumour cells for migration and metastasis are presented and the potential of the intestinal microbiome as a therapeutic target in colorectal carcinogenesis and metastasis is detailed here.

European Society of Coloproctology: guidelines for the management of diverticular disease of the colon.

AIM: The goal of this European Society of Coloproctology (ESCP) guideline project is to give an overview of the existing evidence on the management of diverticular disease, primarily as a guidance to surgeons. METHODS: The guideline was developed during several working phases including three voting rounds and one consensus meeting. The two project leads (JKS and EA) appointed by the ESCP guideline committee together with one member of the guideline committee (WB) agreed on the methodology, decided on six themes for working groups (WGs) and drafted a list of research questions. Senior WG members, mostly colorectal surgeons within the ESCP, were invited based on publication records and geographical aspects. Other specialties were included in the WGs where relevant. In addition, one trainee or PhD fellow was invited in each WG. All six WGs revised the research questions if necessary, did a literature search, created evidence tables where feasible, and drafted supporting text to each research question and statement. The text and statement proposals from each WG were arranged as one document by the first and last authors before online voting by all authors in two rounds. For the second voting ESCP national representatives were also invited. More than 90% agreement was considered a consensus. The final phrasing of the statements with < 90% agreement was discussed in a consensus meeting at the ESCP annual meeting in Vienna in September 2019. Thereafter, the first and the last author drafted the final text of the guideline and circulated it for final approval and for a third and final online voting of rephrased statements. RESULTS: This guideline contains 38 evidence based consensus statements on the management of diverticular disease. CONCLUSION: This international, multidisciplinary guideline provides an up to date summary of the current knowledge of the management of diverticular disease as a guidance for clinicians and patients.

Systematic review and meta-analysis comparing primary resection and anastomosis versus Hartmann's procedure for the management of acute perforated diverticulitis with generalised peritonitis.

BACKGROUND: Surgical strategies for acute perforated diverticulitis with generalised peritonitis remain controversial. This study aimed to meta-analyse trials comparing primary resection and anastomosis (PRA) to Hartmann's procedure (HP) for Hinchey III/IV diverticulitis. METHODS: A systematic literature search was conducted to identify observational studies and randomised control trials (RCTs) of patients with Hinchey III/IV diverticulitis undergoing sigmoidectomy that compared PRA to HP. The methodological quality of the included studies was assessed systematically (Newcastle-Ottawa, Jadad and Cochrane risk of bias scores) and a meta-analysis was performed. RESULTS: After removal of duplicates, 12 studies including 4 RCTs were identified. The analysis included 918 patients, of whom 367 (39.98%) underwent PRA. Both the initial stoma rate (risk ratio [RR] persistent stoma 0.43, 95% confidence interval [CI] 0.26, 0.71, p = 0.001; I2 = 99%, p < 0.0001) and the rate of permanent stoma after combining the first (emergency surgery) and second (stoma reversal) procedures were lower in the PRA group. There was no difference in in 30-day mortality; however, PRA resulted in a reduction in overall mortality as well as major complications after the initial operation (RR 0.67, 95% CI 0.46, 0.97, p = 0.03; I2 = 22%, p = 0.26), stoma reversal (RR 0.48, 95% CI 0.26, 0.92, p = 0.03; I2 = 0%, p = 0.58) and when combining both procedures (RR 0.67, 95% CI 0.51, 0.88, p = 0.005; I2 = 0%, heterogeneity p = 0.58). A subgroup analysis of stoma reversal rates using data from only RCTs were consistent (RR permanent stoma, 0.33, 95% CI 0.13, 0.85, p = 0.02; I2 = 77%, p = 0.004) with the findings of the overall analysis. CONCLUSIONS: This meta-analysis demonstrates that PRA used in the management of haemodynamically stable patients with Hinchey grade III/IV diverticulitis leads to a lower overall persistent stoma rate, with reduced morbidity compared with the traditional management.

Systematic review of outcomes after total neoadjuvant therapy for locally advanced rectal cancer.

BACKGROUND: Advances in surgical technique and the development of combined-modality therapy have led to significantly improved local control in rectal cancer. Distant failure rates however, remain high, ranging between 20 and 30 per cent. Additional systemic chemotherapy in the preoperative period has been proposed as a means of eradicating subclinical micrometastases and improving long-term survival. The purpose of this systematic review was to evaluate the current evidence regarding induction chemotherapy in combination with standard neoadjuvant chemoradiotherapy, in terms of oncological outcomes, in patients with rectal cancer. METHODS: A systematic review of the literature was performed to evaluate oncological outcomes and survival in patients with rectal cancer who underwent induction chemotherapy and neoadjuvant chemoradiotherapy, followed by surgical resection. Four major databases (PubMed, Embase, Scopus and Cochrane) were searched. The review included all original articles published in English reporting long-term outcomes, specifically survival data, and was limited to prospective studies only. RESULTS: A total of 686 studies were identified. After applying inclusion and exclusion criteria, ten studies involving 648 patients were included. Median follow-up was 53·7 (range 26-80) months. Five-year overall and disease-free survival rates were 74·4 and 65·4 per cent respectively. Weighted mean local recurrence and distant failure rates were 3·5 (range 0-7) and 20·6 (range 5-31) per cent respectively. CONCLUSION: Total neoadjuvant therapy should be considered in patients with high-risk locally advanced rectal cancer owing to improved chemotherapy compliance and disease control. Further prospective studies are required to determine whether this approach translates into improved disease-related survival or increases the proportion of patients suitable for non-operative management.

Prospective cohort study of appendicectomy for treatment of therapy-refractory ulcerative colitis.

INTRODUCTION: Appendicectomy may reduce relapses and need for medication in patients with ulcerative colitis, but long-term prospective data are lacking. This study aimed to analyse the effect of appendicectomy in patients with refractory ulcerative colitis. METHODS: In this prospective multicentre cohort series, all consecutive patients with refractory ulcerative colitis referred for proctocolectomy between November 2012 and June 2015 were counselled to undergo laparoscopic appendicectomy instead. The primary endpoint was clinical response (reduction of at least 3 points in the partial Mayo score) at 12 months and long-term follow-up. Secondary endpoints included endoscopic remission (endoscopic Mayo score of 1 or less), failure (colectomy or start of experimental medication), and changes in Inflammatory Bowel Disease Questionnaire (IBDQ) (range 32-224), EQ-5D™ and EORTC-QLQ-C30-QL scores. RESULTS: A total of 28 patients (13 women; median age 40·5 years) underwent appendicectomy. The mean baseline IBDQ score was 127·0, the EQ-5D™ score was 0·65, and the EORTC-QLQ-C30-QL score was 41·1. At 12 months, 13 patients had a clinical response, five were in endoscopic remission, and nine required a colectomy (6 patients) or started new experimental medical therapy (3). IBDQ, EQ-5D™ and EORTC-QLQ-C30-QL scores improved to 167·1 (P < 0·001), 0·80 (P = 0·003) and 61·0 (P < 0·001) respectively. After a median of 3·7 (range 2·3-5·2) years, a further four patients required a colectomy (2) or new experimental medical therapy (2). Thirteen patients had a clinical response and seven were in endoscopic remission. The improvement in IBDQ, EQ-5D™ and the EORTC-QLQ-C30-QL scores remained stable over time. CONCLUSION: Appendicectomy resulted in a clinical response in nearly half of patients with refractory ulcerative colitis and a substantial proportion were in endoscopic remission. Elective appendicectomy should be considered before proctocolectomy in patients with therapy-refractory ulcerative colitis.

ANTECEDENTES: La apendicectomía puede reducir las recaídas y la necesidad de medicación en pacientes con colitis ulcerosa (ulcerative colitis, UC), sin embargo, faltan datos a largo plazo obtenidos de forma prospectiva. El objetivo de este estudio fue analizar el efecto de la apendicectomía en pacientes con UC refractarios al tratamiento. MÉTODOS: En esta serie prospectiva de cohortes multicéntrica, a todos los pacientes consecutivos con UC refractaria remitidos para proctocolectomía entre noviembre de 2012 y junio de 2015 se les recomendó en su lugar someterse a una apendicectomía laparoscópica. El criterio de valoración principal fue la respuesta clínica (disminución de ≥ 3 puntos del sistema de puntuación parcial de Mayo que varía de 0 a 9) a los 12 meses y en el seguimiento a largo plazo. Los criterios de valoración secundarios incluyeron la remisión endoscópica (puntuación endoscópica de Mayo ≤ 1), fracaso (colectomía o inicio de medicación experimental) y cambios en el IBDQ (rango 32-224), EQ-5D y EORTC-QLQ-C30-QL. RESULTADOS: En total, 28 pacientes (13 mujeres, mediana de edad 40,5) se sometieron a una apendicectomía. El IBDQ de referencia promedio fue de 127,0; el EQ-5D 0,65 y el EORTC-QLQ-C30-QL 41,1. A los 12 meses, 13 pacientes presentaban una respuesta clínica, cinco estaban en remisión endoscópica y nueve precisaron colectomía (n = 6) o un nuevo tratamiento médico experimental (n = 3). El IBDQ, EQ-5D y EORTC-QLQ-C30-QL mejoraron a 167,1 (P < 0,001); 0,80 (P = 0,003) y 61,0 (P < 0,001) respectivamente. Después de una mediana de 3,7 años (rango 2,3-5,2), otros cuatro pacientes requirieron una colectomía (n = 2) o un nuevo tratamiento médico experimental (n = 2). Trece pacientes presentaron respuesta clínica y siete se encontraban en remisión endoscópica. La mejora del IBDQ, el EQ-5D y el EORTC-QLQ-C30-QL se mantuvo estable a lo largo del tiempo. CONCLUSIÓN: La apendicectomía consiguió una respuesta clínica en casi la mitad de los pacientes con UC refractaria. La apendicectomía electiva debería ser considerada antes que la proctocolectomía en pacientes con UC refractaria al tratamiento.

Meta-analysis of the effect of extending the interval after long-course chemoradiotherapy before surgery in locally advanced rectal cancer.

BACKGROUND: The current standard of care in locally advanced rectal cancer (LARC) is neoadjuvant long-course chemoradiotherapy (nCRT) followed by total mesorectal excision (TME). Surgery is conventionally performed approximately 6-8 weeks after nCRT. This study aimed to determine the effect on outcomes of extending this interval. METHODS: A systematic search was performed for studies reporting oncological results that compared the classical interval (less than 8 weeks) from the end of nCRT to TME with a minimum 8-week interval in patients with LARC. The primary endpoint was the rate of pathological complete response (pCR). Secondary endpoints were recurrence-free survival, local recurrence and distant metastasis rates, R0 resection rates, completeness of TME, margin positivity, sphincter preservation, stoma formation, anastomotic leak and other complications. A meta-analysis was performed using the Mantel-Haenszel method. RESULTS: Twenty-six publications, including four RCTs, with 25 445 patients were identified. A minimum 8-week interval was associated with increased odds of pCR (odds ratio (OR) 1·41, 95 per cent c.i. 1·30 to 1·52; P < 0·001) and tumour downstaging (OR 1·18, 1·05 to 1·32; P = 0·004). R0 resection rates, TME completeness, lymph node yield, sphincter preservation, stoma formation and complication rates were similar between the two groups. The increased rate of pCR translated to reduced distant metastasis (OR 0·71, 0·54 to 0·93; P = 0·01) and overall recurrence (OR 0·76, 0·58 to 0·98; P = 0·04), but not local recurrence (OR 0·83, 0·49 to 1·42; P = 0·50). CONCLUSION: A minimum 8-week interval from the end of nCRT to TME increases pCR and downstaging rates, and improves recurrence-free survival without compromising surgical morbidity.

ANTECEDENTES: El tratamiento estándar actual del cáncer de recto localmente avanzado (locally advanced rectal cancer, LARC) consiste en quimiorradioterapia neoadyuvante de ciclo largo (neoadjuvant, long-course chemoradiation, nCRT) seguida de exéresis total del mesorrecto (total mesorectal excision, TME). De forma convencional, la cirugía se realiza a las 6-8 semanas después de la nCRT. Este estudio tuvo como objetivo determinar el efecto sobre los resultados de ampliar este intervalo. MÉTODOS: Se realizó una búsqueda sistemática de los estudios que analizaban los resultados oncológicos, comparando el intervalo clásico (< 8 semanas) desde el final de la nCRT hasta la TME con un intervalo mínimo de 8 semanas, en pacientes con LARC. El criterio de valoración principal fue la tasa de respuesta patológica completa (pathologic complete response, pCR). Los criterios de valoración secundarios fueron las tasas de supervivencia sin recidiva (recurrence-free survival, RFS), recidiva local (local recurrence, LR) y metástasis a distancia (distant metastasis, DM), tasas de resección R0, integridad (completeness) del mesorrecto, afectación del margen de resección, preservación esfinteriana, formación de estoma, fuga anastomótica y otras complicaciones. Se realizó un metaanálisis utilizando el método de Mantel-Haenszel. RESULTADOS: Se identificaron 26 publicaciones, incluidos cuatro ensayos clínicos aleatorizados, con 17.220 pacientes. Un intervalo mínimo de 8 semanas se asoció con un aumento de la razón de oportunidades (odds ratio, OR) de pCR (OR, 1,68, i.c. del 95% 1,37-2,06, P < 0,001) y de disminución del estadio tumoral (OR 1,18, i.c. del 95% 1,05-1,32, P = 0,004). Los porcentajes de resección R0, integridad del mesorrecto, ganglios linfáticos identificados, preservación esfinteriana, formación de estoma y complicaciones fueron similares entre los dos grupos. El aumento del porcentaje de pCR se tradujo en una disminución de las DM (OR 0,71, i.c. del 95% 0,54-0,93, P = 0,01) y de la recidiva global (OR 0,76, i.c. del 95% 0,58-0,98, P = 0,04), pero no de la LR (OR 0,83, i.c. del 95% 0,49-1,42, P = 0,50). CONCLUSIÓN: Un intervalo mínimo de 8 semanas entre el final de la nCRT y la TME aumenta las tasas de pCR y la reducción del estadio tumoral, así como mejora la RFS sin comprometer la morbilidad quirúrgica.

Minimally invasive approaches to the management of anastomotic leakage following restorative rectal cancer resection.

AIM: Management of anastomotic leakage (AL) following rectal resection has evolved with increasing use of less invasive techniques. The aim of this study was to review the management of AL following restorative rectal cancer resection in a tertiary referral centre. METHOD: A retrospective review of a prospectively maintained database was performed. The primary outcome was successful management of AL. The secondary outcome was the impact of AL on oncological outcome. RESULTS: Five hundred and two restorative rectal cancer resections were performed during the study period. The incidence of AL was 9.9% (n = 50). AL occurred more commonly following neoadjuvant chemoradiotherapy (n = 31/252, 12.3%) than in those who did not receive neoadjuvant chemoradiotherapy (n = 19/250, 7.6%; P = 0.107); however, this was not statistically significant. Successful minimally invasive drainage was achieved in 28 patients (56%, radiological n = 24, surgical n = 4). Trans-rectal drainage was the most common drainage method (n = 14). The median duration of drainage was longer in the neoadjuvant group (27 vs 18 days). Surgical intervention was required in 11 patients, with anastomotic takedown and end-colostomy formation was most commonly required. Successful management of AL with drainage (maintenance of the anastomosis without the need for further intervention) was achieved in 26 of the 28 patients. There were no significant differences in overall or disease-free survival when patients with AL were compared with patients without AL (69.4% vs 72.6%, P = 0.99 and 78.7% vs 71.3%, P = 0.45, respectively). CONCLUSION: In selected patients, AL following restorative rectal resection can be effectively controlled using minimally invasive radiological or surgical drainage without the need for further intervention.

Open and Endovascular Management of Acute Mesenteric Ischaemia: A Systematic Review.

BACKGROUND: Acute mesenteric ischaemia (AMI) is a life-threatening surgical emergency resulting from thromboembolic occlusion of the mesenteric vasculature. Traditional management of AMI has been open revascularisation with or without bowel resection-a procedure which carries considerable morbidity and mortality in an already unwell, compromised patient. Endovascular and more minimally invasive management approaches to AMI have been reported. Proponents of endovascular management suggest this approach may be associated with reduced morbidity and mortality compared with open surgery. OBJECTIVES: To assess the impact of endovascular approach for AMI on mortality and need for subsequent laparotomy and/or bowel resection. DATA SOURCES: The search bodies PubMed and Medline were interrogated. ELIGIBILITY CRITERIA, PARTICIPANTS AND INTERVENTIONS: All studies in English with greater than 10 patients examining outcomes for patients undergoing endovascular intervention for acute mesenteric ischaemia were included. All patients over 18 years presenting with a diagnosis of acute mesenteric ischaemia secondary to an arterial thromboembolic source were included. Studies examining endovascular intervention alone or endovascular and open intervention were selected. RESULTS: The 30-day mortality for endovascular approach from all 13 studies was 16-42%. Of the 7 comparative studies including results of open revascularisation, the 30-day mortality for patient treated with an endovascular approach was 15-39% versus 33-50% for open revascularisation. Laparotomy rates post-initial endovascular intervention ranged from 13 to 73%. Bowel resection post-endovascular therapy ranged from 14 to 40% among studies. Concerning 7 comparative studies for open versus endovascular revascularisation, the rate of bowel resection in the endovascular group ranged 14-28% and 33-63% in the open cohort. Endovascular intervention also demonstrated lower median length (s) of bowel resected. LIMITATIONS: Heterogeneity of studies and patient populations studied including selection bias. CONCLUSIONS AND IMPLICATIONS OF FINDINGS: Endovascular management may be associated with reduced mortality and need for/length of bowel resection compared with the traditional open approach, but there remains a paucity of robust data to support this. The available literature illustrates that a subgroup of patients without haemodynamic compromise and more insidious onset may garner benefit from endovascular intervention.

Close rectal dissection in benign diseases of the rectum: A review.

PURPOSE: Total mesorectal excision (TME) is the gold standard resectional strategy for rectal cancer to minimize loco-regional recurrence and optimize oncological outcomes. This plane is described by many as 'bloodless' but it does contain important pelvic neural plexuses and dissection may be close to the ureters and major vascular structures, particularly in inflammatory conditions of the distal colon and rectum. In such benign diseases a more conservative excision, so-called close rectal dissection, has been advocated to minimize damage to these structures. METHODS: A review of the literature was conducted to document the evolution of this procedure. Contemporary literature was interrogated to ascertain how this approach is adopted in minimally invasive surgery. Post-operative outcomes are compared to those from TME surgery. RESULTS: From early descriptions in 1956, this procedure has been adapted for use in laparoscopic surgery. It may be particularly useful in trans-anal mesorectal surgery. Reported benefits include reduced nerve injury and pelvic sepsis. However, this must be balanced against risks of mesorectal bleeding, rectal injury, and ongoing inflammation from the retained mesorectum. CONCLUSION: Rectal surgery in inflammatory conditions is technically challenging. Close rectal dissection is an alternate approach available to colorectal surgeons in these cases to minimize pelvic morbidity and optimize postoperative outcomes.

Stoma rods in abdominal surgery: a systematic review and metaanalyses.

BACKGROUND: Stoma rods are used traditionally to prevent retraction of loop stomas into the abdominal cavity. However, there is very little evidence to support or refute their use. The aim of the present systematic review and metaanalysis was to assess the current data on stoma rods in loop stomas. The primary outcomes were stoma necrosis and stoma retraction. METHODS: A systematic review and metaanalyses were conducted using the preferred reporting items for systematic reviews and metaanalysis guidelines (PRISMA). The study protocol was registered prospectively on PROSPERO. An electronic search was performed by two reviewers independently using predefined search strategy and Medline. Bibliographies of selected studies were screened for additional references. RevMan was used to generate forest plots and calculate odds ratios and 95% confidence intervals (CIs). RESULTS: In total, five studies were identified that met inclusion criteria, including four randomized controlled trials. Three studies examined only ileostomies, while one included both colostomies and ileostomies, and one only examined colostomies. In total, 561 patients underwent a stoma with a rod compared to 443 without. There was a higher rate of dermatitis (rod 29.86% vs no rod 16% OR 2.65; 95% CI 1.79-3.93) and stoma necrosis (rod 7% vs no rod 1.15% OR 5.58; 95% CI 1.85-16.84) in the rod group, but there was no significant difference in stoma retraction (rod 2.28% vs no rod 3.45%; OR 0.7; 95% CI 0.32-1.54). CONCLUSIONS: Stoma rods do not reduce the incidence of stoma retraction and instead lead to increased rates of dermatitis and stoma necrosis.

Isolating Clusters of Light Elements in Molecular Sieves with Atom Probe Tomography.

Understanding the 3-D distribution and nature of active sites in heterogeneous catalysts is critical to developing structure-function relationships. However, this is difficult to achieve in microporous materials as there is little relative z-contrast between active and inactive framework elements (e.g., Al, O, P, and Si), making them difficult to differentiate with electron microscopies. We have applied atom probe tomography (APT), currently the only nanometer-scale 3-D microscopy to offer routine light element contrast, to the methanol-to-hydrocarbons (MTH) catalyst SAPO-34, with Si as the active site, which may be present in the framework as either isolated Si species or clusters (islands) of Si atoms. 29Si solid-state NMR data on isotopically enriched and natural abundance materials are consistent with the presence of Si islands, and the APT results have been complemented with simulations to show the smallest detectable cluster size as a function of instrument spatial resolution and detector efficiency. We have identified significant Si-Si affinity in the materials, as well as clustering of coke deposited by the MTH reaction (13CH3OH used) and an affinity between Brønsted acid sites and coke. A comparison with simulations shows that the ultimate spatial resolution that can be attained by APT applied to molecular sieves is 0.5-1 nm. Finally, the observed 13C clusters are consistent with hydrocarbon pool mechanism intermediates that are preferentially located in regions of increased Brønsted acidity.