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Background Long-term multicentre studies are subject to numerous factors that may affect the integrity of their conclusions. Quality control and standardization of data collection are crucial to minimise the biases induced by these factors. Nevertheless, tools implemented to manage biases are rarely described in publications about population-based cohorts. This report aims to describe the processes implemented to control biases in the Constances cohort taking lung function results as an example. Methods Constances is a general-purpose population-based cohort of 200,000 participants. Volunteers attend physical examinations at baseline and then every 5 years at selected study sites. Medical device specifications and measurement methods have to comply with Standard Operating Procedures developed by experts. Protocol deviations are assessed by on-site inspections and database controls. In February 2016, more than 94,000 participants yielding around 30 million readings from physical exams, had been covered by our quality program. Results Participating centres accepted to revise their practices in accordance with the study research specifications. Distributors of medical devices were asked to comply with international guidelines and Constances requirements. Close monitoring enhanced the quality of measurements and recordings of the physical exams. Regarding lung function testing, spirometry acceptability rates per operator doubled in some sites within a few months and global repeatability reached 96.7 % for 29,772 acceptable maneuvers. Conclusions Despite Constances volunteers being followed in multiple sites with heterogeneous materials, the investment of significant resources to set up and maintain a continuous quality management process has proved effective in preventing drifts and improving accuracy of collected data.

Background Prospective cohorts represent an essential design for epidemiological studies and allow for the study of the combined effects of lifestyle, environment, genetic predisposition, and other risk factors on a large variety of disease endpoints. The CONSTANCES cohort is intended to provide public health information and to serve as an \"open epidemiologic laboratory\" accessible to the epidemiologic research community. Although designed as a \"general-purpose\" cohort with very broad coverage, it will particularly focus on occupational and social determinants of health, and on aging. Methods/Design The CONSTANCES cohort is designed as a randomly selected representative sample of French adults aged 18-69 years at inception; 200,000 subjects will be included over a five-year period. At inclusion, the selected subjects will be invited to fill a questionnaire and to attend a Health Screening Center (HSC) for a comprehensive health examination: weight, height, blood pressure, electrocardiogram, vision, auditory, spirometry, and biological parameters; for those aged 45 years and older, a specific work-up of functional, physical, and cognitive capacities will be performed. A biobank will be set up. The follow-up includes a yearly self-administered questionnaire, and a periodic visit to an HSC. Social and work-related events and health data will be collected from the French national retirement, health and death databases. The data that will be collected include social and demographic characteristics, socioeconomic status, life events, behaviors, and occupational factors. The health data will cover a wide spectrum: self-reported health scales, reported prevalent and incident diseases, long-term chronic diseases and hospitalizations, sick-leaves, handicaps, limitations, disabilities and injuries, healthcare utilization and services provided, and causes of death. To take into account non-participation at inclusion and attrition throughout the longitudinal follow-up, a cohort of non-participants will be set up and followed through the same national databases as participants. A field-pilot was performed in 2010 in seven HSCs, which included about 3,500 subjects; it showed a satisfactory structure of the sample and a good validity of the collected data. Discussion The constitution of the full eligible sample is planned during the last trimester of 2010, and the cohort will be launched at the beginning of 2011.

Evidence-based counseling and prevention are not available so far for hereditary cancer prone persons, since we lack data based on clinical trials. There are very few high-risk persons in the population as a whole. Based on a familial history analysis, only 1.2% of all healthy volunteers attending screening centers reached the arbitrary high-risk level defined as a Relative Risk of more than 4. We describe a randomized trial based on colonoscopic screening for colorectal cancer on a sub-group of high-risk group persons. Among the 77 members of the French Institutional Preventive Center Network, 37 took part in this protocol. During the first 3 years, 850,000 persons were interviewed at these 37 Health centers. The enrollment process was particularly time-consuming, since a large amount of information had to be delivered to the participants. The mean rate of recruitment of eligible candidates was far lower than predicted, averaging only 1.4 per 1,000 persons interviewed instead of the 9/1,000 expected. This mean figure was based, however, on inclusion rates ranging from 0.06/1,000 to 7/1,000 among the different centers. The low rates of recruitment were mainly due to the inter-center heterogeneity (differences in commitment and in the resources), and to the fact that the acceptability of undergoing a colonoscopy turned out to be lower than predicted. Population trials on cancer prone persons are feasible, but vast numbers have to be pre- screened to identify the few people with a high hereditary risk and willing to accept screening within a controlled trial.

Introduction Bariatric surgery can become technically challenging in the setting of liver steatosis and hepatomegaly. The protein sparing modified fast (PSMF) diet helps in achieving rapid weight loss. The aim of this study is to explore the results of a preoperative PSMF diet on liver volume and steatosis as well as on intraoperative and postoperative complications in patients with hepatomegaly undergoing Roux-en-Y gastric bypass (RYGB). Methods Between January 2010 and January 2021, 713 patients undergoing RYGB as a primary bariatric surgery were divided in two groups. Those with a measured liver length above 16 cm and or evidence of liver steatosis on ultrasound (group 1) were offered a preoperative PSMF diet while the remaining (group 2) proceeded directly to surgery. Between January 2010 and April 2012, patients included in group 1 had liver volume measurements on magnetic resonance imaging the day before the diet was started and the day before the surgery. For the length of the study, intraoperative and postoperative data were recorded for both groups. Results Five days of preoperative PSMF diet resulted in a significant reduction of total and left liver volume (15.8% and 21% respectively, p  < 0.001). There was no difference in intraoperative bleeding and conversion rate or postoperative complication rate between both groups. Conclusion The PSMF diet helps in achieving a rapid decrease in liver volume. Patients with hepatomegaly initially thought to be at a higher risk of intraoperative complications reached comparable rates to patients without hepatomegaly after the diet regimen without any impact on the postoperative course. Graphical Abstract

Background The impact of discrepancies between clinical (c) and pathologic (p) stages of esophageal cancer remains a poorly understood issue. This study aimed to compare the prognosis of patient groups treated by primary surgery including clinical N0/pathologic N0 (cN0pN0), clinical N0/pathologic N+ (cN0pN+), clinical N+/pathologic N0 (cN+pN0), and clinical N+/pathologic N+ (cN+pN+). Methods Data were collected from 30 European centers during the years 2000 to 2010. Among 2944 recruited patients, 1554 patients receiving primary surgery met the inclusion criteria including 613 cN0pN0, 403 cN0pN+, 220 cN+pN0, and 318 cN+pN+ patients. Analyses with adjustment of the propensity score were used to compensate for differences in baseline characteristics. Results Clinical T stages 3 and 4 were increased in cN+pN+ (73.0%), cN0pN+ (49.6%), and cN+pN0 (51.8%) compared with cN0pN0 (32.8%). Compared with cN0pN0, cN+pN+ and cN0pN+ showed an increase in the proportion of adenocarcinoma histologic subtype, poor tumor differentiation, pathologic T3 and T4 stages, and R1/2 resection margin. Adjusted 5-year overall survival (hazard ratio [HR] 3.12; 95% confidence interval [CI] 2.57–3.78; P  < 0.001) and event-free survival (HR 2.87; 95% CI 2.39–3.45; P  < 0.001) were significantly reduced in cN0pN+ compared with cN0pN0. No significant differences in 5-year overall survival or event-free survival between cN0pN+ and cN+pN+ were observed. Regression analysis identified an association of distal tumor location, advanced clinical T stage, and poor tumor differentiation with pN+ disease. Conclusions This large multicenter study showed that cN0pN+ has a prognosis similar to that of cN+pN+ and worse than that of cN0pN0. Patients with clinical N0 disease but risk factors for pathologic N+ disease may benefit from neoadjuvant therapy before surgery.

Background The prognosis and chemoresistance of signet-ring cell (SRC) gastric adenocarcinoma have been reported and debated, and the utility of perioperative chemotherapy for such a tumor has been questioned . This study was performed to assess the impact of the SRC type on survival following resection of gastric adenocarcinoma, and to assess whether the prognostic factors (including perioperative chemotherapy) for non-SRC adenocarcinoma differed from those for SRC adenocarcinoma. Methods 1799 cases of adenocarcinoma that were consecutively treated from 1997 to 2010 in 19 French centers by subtotal or total gastrectomy were included in a retrospective study. A D2 lymphadenectomy was performed for antropyloric tumors, and a modified D2 for upper tumors. SRC adenocarcinoma was diagnosed based on the presence of isolated carcinoma cells containing mucin. Results A total gastrectomy was performed in 979 (54.4 %) patients. SRC adenocarcinoma was diagnosed in 899 (50 %) patients. Patients with an SRC tumor were more frequently female, younger, and malnourished, had lower ASA scores, and had larger tumors than non-SRC patients. Median survival in patients with non-SRC carcinoma was 51 months, as compared to 26 months in patients with SRC carcinoma ( p  < 0.001). At multivariate analysis, SRC type remained an independent adverse prognostic factor (HR = 1.182). Factors that were prognostic in the SRC subgroup but not in the non-SRC subgroup were age >60 years, linitis, and involvement of adjacent organs. In contrast to non-SRC tumors, pre- and postoperative chemotherapy did not significantly impact on survival following resection of SRC adenocarcinoma. Conclusion In comparison to non-SRC adenocarcinoma, the SRC type has a worse prognosis, different prognostic factors, and is only poorly sensitive to perioperative chemotherapy. Non-SRC and SRC adenocarcinomas should be considered different entities in future therapeutic trials.

Background While the incidence of esophageal and gastric cancers is increasing, the prognosis of these cancers remains bleak. Endoscopy and surgery are the standard treatments for localized tumors, but multimodal treatments, associated chemotherapy, targeted therapies, immunotherapy, radiotherapy, and surgery are needed for the vast majority of patients who present with locally advanced or metastatic disease at diagnosis. Although survival has improved, most patients still present with advanced disease at diagnosis. In addition, most patients exhibit a poor or incomplete response to treatment, experience early recurrence and have an impaired quality of life. Compared with several other cancers, the therapeutic approach is not personalized, and research is much less developed. It is, therefore, urgent to hasten the development of research protocols, and consequently, develop a large, ambitious and innovative tool through which future scientific questions may be answered. This research must be patient-related so that rapid feedback to the bedside is achieved and should aim to identify clinical-, biological- and tumor-related factors that are associated with treatment resistance. Finally, this research should also seek to explain epidemiological and social facets of disease behavior. Methods The prospective FREGAT database, established by the French National Cancer Institute, is focused on adult patients with carcinomas of the esophagus and stomach and on whatever might be the tumor stage or therapeutic strategy. The database includes epidemiological, clinical, and tumor characteristics data as well as follow-up, human and social sciences quality of life data, along with a tumor and serum bank. Discussion This innovative method of research will allow for the banking of millions of data for the development of excellent basic, translational and clinical research programs for esophageal and gastric cancer. This will ultimately improve general knowledge of these diseases, therapeutic strategies and patient survival. This database was initially developed in France on a nationwide basis, but currently, the database is available for worldwide contributions with respect to the input of patient data or the request for data for scientific projects. Trial registration The FREGAT database has a dedicated website ( www.fregat-database.org ) and is registered on the Clinicaltrials.gov site, number NCT 02526095 , since August 8, 2015.