The impact of transanal local excision of early rectal cancer on completion rectal resection without neoadjuvant chemoradiotherapy: a systematic review

Background The impact of transanal local excision (TAE) of early rectal cancer (ERC) on subsequent completion rectal resection (CRR) for unfavorable histology or margin involvement is unclear. The aim of this study was to provide a comprehensive review of the literature on the impact of TAE on CRR in patients without neoadjuvant chemoradiotherapy (CRT). Methods We performed a systematic review of the literature up to March 2020. Medline and Cochrane libraries were searched for studies reporting outcomes of CRR after TAE for ERC. We excluded patients who had neoadjuvant CRT and endoscopic local excision. Surgical, functional, pathological and oncological outcomes were assessed. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed. Results Sixteen studies involving 353 patients were included. Pathology following TAE was as follows T0 = 2 (0.5%); T1 = 154 (44.7%); T2 = 142 (41.2%); T3 = 43 (12.5%); Tx = 3 (0.8%); T not reported = 9. Fifty-three percent were > T1. Abdominoperineal resection (APR) was performed in 80 (23.2%) patients. Postoperative major morbidity and mortality occurred in 22 (11.4%) and 3 (1.1%), patients, respectively. An incomplete mesorectal fascia resulting in defects of the mesorectum was reported in 30 (24.6%) cases. Thirteen (12%) patients developed recurrence: 8 (3.1%) local, 19 (7.3%) distant, 4 (1.5%) local and distant. The 5-year cancer-specific survival was 92%. Only 1 study assessed anal function reporting no continence disorders in 11 patients. In the meta-analysis, CRR after TAE showed an increased APR rate (OR 5.25; 95% CI 1.27-21.8; p 0.020) and incomplete mesorectum rate (OR 3.48; 95% CI 1.32-9.19; p 0.010) compared to primary total mesorectal excision (TME). Two case matched studies reported no difference in recurrence rate and disease free survival respectively. Conclusions The data are incomplete and of low quality. There was a tendency towards an increased risk of APR and poor specimen quality. It is necessary to improve the accuracy of preoperative staging of malignant rectal tumors in patients scheduled for TAE

Field-study science classrooms as positive and enjoyable learning environments

We investigated differences between field-study classrooms and traditional science classrooms in terms of the learning environment and students’ attitudes to science, as well as the differential effectiveness of field-study classrooms for students differing in sex and English proficiency. A modified version of selected scales from the What Is Happening In this Class? questionnaire was used to assess the learning environment, whereas students’ attitudes were assessed with a shortened version of a scale from the Test of Science Related Attitudes. A sample of 765 grade 5 students from 17 schools responded to the learning environment and attitude scales in terms of both their traditional science classrooms and classrooms at a field-study centre in Florida. Large effect sizes supported the effectiveness of the field-studies classroom in terms of both the learning environment and student attitudes. Relative to the home school science class, the field-study class was considerably more effective for students with limited English proficiency than for native English speakers

A DETERMINISTIC APPROACH TO UNDERSTANDING THE SENSITIVITY OF SURFACE DUCT PROPAGATION TO SOUND SPEED FEATURES IN THE UPPER OCEAN

A key sound speed feature of the upper ocean is the Mixed Layer Acoustic Duct (MLAD). Acoustic propagation effects due to mean properties of the duct and spatial and temporal variability are thought to be strong functions of acoustic frequency. Key physical mechanisms at work are diffractive leakage and mode coupling. Using both analytic theory and direct numerical simulation, this thesis will examine 400 and 1000 Hz MLAD propagation characteristics by calculating the sensitivity of duct propagation to various ocean perturbations with horizontal scales ranging from 0.5 to 15 km. As a starting point, sound speed profiles (SSP) typical of the spring-summer transition in the North Atlantic are considered. Tools used are first-order mode scattering theory originally developed for shallow water propagation, and direct numerical simulation. Numerical simulations are compared to theory with the goals of 1) evaluating the utility of the shallow water analytic approach for deep water MLADs and 2) putting forward a metric for estimating MLAD stability as a function of frequency and perturbation scales. Results show that while the shallow water analytic approach is not accurate enough for the MLAD due to higher order mode interaction, first-order mode energy equation motivates the non-dimensional interaction matrix, Γmn, which showed strong correlation between multiple scattering events and increased acoustic variability when Γmn > 1.Outstanding ThesisLieutenant Commander, United States NavyApproved for public release. distribution is unlimite

The degree of extramural spread of T3 rectal cancer: a plea to the UICC and AJCC

The T3-stage of the TNM classification includes over 60% of all rectal tumours and encompasses the greatest variance in cancer specific end points than any other T stage. Despite this the Union Internationale Contre le Cancer (UICC) and the American Joint Committee on Cancer (AJCC) classifications do not divide T3 tumours into subgroups which reflect cancer specific outcome more sensitively. A review of the literature was undertaken to assess the influence of the degree of extramural extent of T3 rectal cancer on local recurrence and survival

The risk of lymph node metastasis in T1 colorectal cancer: new parameters to assess the degree of submucosal invasion

Purpose: In T1 colorectal cancer, the depth is the main factor assessing the degree of submucosal invasion (DSI) to predict the risk of lymph node metastasis (LNM). The width (WSI) and the area of submucosal invasion (ASI) have been suggested as additional parameters to assess the risk of LNM. A review of the literature was undertaken on the correlation between WSI and ASI parameters and the incidence of LNM. Methods: A Medline, PubMed, and Cochrane Library search was performed to retrieve all studies reporting correlation between WSI/ASI and risk of LNM in T1 colorectal cancer. Results: Eight studies including 1727 patients were identified. All considered the degree of WSI and its influence on LNM: seven assessed different width cut-off of submucosal invasion, and one study the mean width of submucosal invasion in patients having or not involved lymph nodes. The WSI was significantly a prognostic factor for LNM (p < 0.05) in four studies. Both 2 and 3 mm seem to be the most discriminatory cut-off values of submucosal width invasion in defining the risk difference of LNM above and below the cut-off (2 mm, OR = infinite; 3 mm, OR = 6.9). Patients having a cut-off ≤ 5 mm of WSI showed a low risk (5.6%) of LNM rendering radical surgery unnecessary. Four studies assessed the risk of LNM according to the involved submucosal area (width × depth). In two of these, the ASI was a significant prognostic factor for LNM (p < 0.05). Conclusion: The WSI and ASI seem to be reliable prognostic factors for LNM in T1 colorectal cancer. There is no agreement on ideal cut-off value

A simple bowel habit score for colorectal patients

The assessment of bowel habit is important in the management of patients with colorectal disease. There is not an ideal and practical bowel habit scoring system. The current scores have been designed only for a subclass of patients having a particular disorder. Furthemore, they are complex and time consuming. We propose a simple score to quickly assess the bowel function in all patients with proctological disorders