Vertical R1 margins are not always associated with residual neoplasia after endoscopic resection of Barrett's neoplasia: a nationwide cohort with dedicated pathology reassessment

Background: To evaluate the proportion of patients with residual neoplasia after endoscopic resection (ER) for Barrett's neoplasia with confirmed tumor-positive vertical resection margin (R1v). Methods: Retrospective cohort study including all patients treated with ER for Barrett's neoplasia with histologically documented R1v since 2008 in the Dutch Barrett Expert Centers. R1v was defined as cancer cells touching the vertical resection margin and Rx as not assessable margins. Reassessment of R1v specimen was performed by experienced pathologists until consensus was reached regarding vertical margins. Results: 101/110 included patients had macroscopically complete resections (T1a n=17, T1b n=84), of which 99/101 (98%) ER specimens were reassessed. Reassessment confirmed R1v in 74 (75%) patients and found Rx in 16% and R0 in 9%. Presence of residual neoplasia could be assessed in 66/74 patients during endoscopic reassessment (n=52) and/or in the surgical resection specimen (n=14), of whom 33/66 (50%)had residual neoplasia. Residual neoplasia detected during endoscopy was always endoscopically visible and biopsies from a normal appearing ER-scar did not detect additional neoplasia. Twenty-five patients with no residual neoplasia during endoscopic reassessment underwent endoscopic follow-up for median 37 months(IQR 12-50), in which 4 developed a local recurrence(16.0%), all detected as visible abnormalities. Conclusions: Histological evaluation of ER margins appears challenging as 75% of documented R1v cases were confirmed during reassessment. After ER with R1v, 50% of the patients had no residual neoplasia. Endoscopic reassessment 8-12 weeks after ER seems accurately able to detect residual neoplasia and help to determine the most appropriate strategy for patients with R1v

PET in Brain Arteriovenous Malformations and Cerebral Proliferative Angiopathy

A brain arteriovenous malformation (BAVM) is a neurovascular entity that consists of a localized dense network of abnormal blood vessels (a nidus) that holds arteries shunting directly into veins in the absence of a capillary bed. In their natural history, BAVMs carry a risk of hemorrhage or other neurological complications, for which reason they are frequently treated. Cerebral proliferative angiopathy (CPA) is a different type of neurovascular malformation with distinct angiographic and clinical features that can be used to differentiate it from a classical BAVM. The basic difference between CPA and a BAVM is that CPA has normal brain tissue intermingled in between its network of vessels. Treatment of CPA by surgery, radiosurgery, or embolization consequently harbors a high risk of neurological complications. As such, reliable diagnostic discrimination between CPA and BAVM is crucial to adequately treat patients. However, despite the fact that CPA has some characteristic imaging features, the differentiation between CPA and a brain AVM may be difficult. PET imaging as a technique that reveals functional brain tissue is therefore likely to be of additional diagnostic value.<br/

Effects of Single-Sex Schooling in the Final Years of High School: A Comparison of Analysis of Covariance and Propensity Score Matching

Typically, the effects of single-sex schooling are small at best, and tend to be statistically non-significant once pre-existing differences are taken into account. However, researchers often have had to rely on observational studies based on small non-representative samples and have not used more advanced propensity score methods to control the potentially confounding effects of covariates. Here, we apply optimal full matching to the large historical longitudinal dataset best suited to evaluating this issue in US high schools: the nationally representative High School and Beyond study. We compare the effects of single-sex education in the final 2 years of high school on Grade 12 and post-secondary outcomes using the subsample of students attending Catholic schools (N = 2379 students, 29 girls' schools, 22 boys' schools, 33 coeducational schools) focusing on achievement-related, motivational and social outcomes. We contrast conventional Analysis of Covariance (ANCOVA) with optimal full matching based on the propensity score that provides a principled way of controlling for selection bias. Results from the two approaches converged: When background and Year 10 covariates were controlled, uncorrected apparent differences between the school types disappeared and the pattern of effects was very similar across the two methods. Overall, there was little evidence for positive effects of single-sex schooling for a broad set of outcomes in the final 2 years of high school and 2 years after graduation. We conclude with a discussion of the advantages of propensity score methods compared to ANCOVA