Five Year Oncological Outcome After CME for Right-sided Colon Cancer

Study Overview
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Brief Summary
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Study based on existing databases investigating the causal oncological treatment effects of complete mesocolic excision on UICC stage I-III right-sided colon cancer.

Detailed Description
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Population-based cohort study, predominantly prospective based, on the same population as the investigator's previously study comparing short-term outcome after CME with conventional colon resections. The COMES database combines the prospectively registered colon cancer database in Hillerød (CME data), and data from the national database of the Danish Colorectal Cancer Group (DCCG) covering patients undergoing conventional resection (non-CME) in the other three centers. The medical records of all the patients in the non-CME group (control group) were reviewed by colorectal surgeons from Hillerød. Data audit for all CME patients was performed by various co-authors employed at the other centers. A similar audit of data for non-CME patients having postoperative complications or recurrence was performed by the co-author representing the department treating the specific patients. Statistical analysis plan Continuous data are presented as median and interquartile ranges, and categorical data as frequencies and proportions. Kruskal-Wallis test and Fisher's exact test were used as appropriate. Death is a competing risk to recurrence and time-to-event analyses were performed as competing risk analyses obtaining the cumulative incidences for recurrence or death using the cmprsk R-package. Unbiased estimation of marginal or population-averaged treatment effects in observational and non-randomized studies can be obtained through different propensity score methods. Inverse Probability of Treatment Weighting (IPTW) uses the propensity score to weight each patient's data based on the inverse probability of receiving the treatment actually received. IPTW gives unbiased estimates of average treatment effects in time-to-event analyses if no differences in observed baseline covariates exist between the treatment groups. To account for baseline differences between patients in the two groups, stabilized weights truncated at the 0.99 interval were calculated using the IPW R-package. The following baseline covariates will be used: age, sex, ASA score, neoadjuvant chemotherapy, tumor location, tumor morphology, perineural invasion, extramural venous invasion, tumor stage, and serosal invasion. All covariates used and UICC stage, two-way interactions, and squared terms of continuous covariates will be assessed for balance between the CME and the non-CME group after IPTW using the cobalt R-package. Absolute mean differences in mean (using standardized mean difference) and proportions (using raw mean difference) below 0.1, variance ratios between 0.5 and 2, and Kolmogorov-Smirnov tests equal or below 0.05 will be accepted. Graphical inspection of the distribution of covariates will be also performed. The cause-specific hazards and overall survival will be analyzed using Cox regression. Binary outcomes will be analyzed using logistic regression. Lymph node yield will be analyzed using linear regression after logarithmic transformation. Number of metastatic lymph nodes will be analyzed using negative binominal regression. All analyses of primary and secondary outcomes will be performed after IPTW. The 95% confidence intervals for the estimates from the original Cox regression IPTW analyses will be constructed after 1000 bootstraps with replacement, and a robust sandwich estimator will be used for the logistic regression analyses in order to ensure correct variance estimation. All available data will be used. Model assumptions will be checked. A p-value below or equal to 0.05 will be considered significant. All analyses will be performed using R statistical software, version 3.5.1 (R Foundation for Statistical Computing, Vienna, Austria).

Official Title
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Five Year Oncological Outcome After Complete Mesocolic Excision for Right-sided Colon Cancer: a Population-based Cohort Study

Conditions
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Colonic Neoplasms

Intervention / Treatment
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* Procedure: Complete mesocolic excision
* Procedure: Conventional colon resections


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Right-sided colon cancer was defined as primary adenocarcinomas located in the cecum, ascending colon hepatic flexure, right or mid third of the transverse colon. UICC stage I-III - Gastroepiploic and infrapyloric lymph node metastases are not considered as distant metastases Exclusion Criteria: Synchronous colorectal cancer - even in the right colon No residual tumor in the specimen after neoadjuvant chemotherapy Metachronous colorectal cancer Appendix cancers Resections in Hillerød not performed according to the principles of CME Non-macroradical (R2) resections (peroperative assessment)

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| CME group<br>The CME group consisted of patients, who underwent elective CME for right-sided colon adenocarcinoma at Nordsjaellands Hospital Hillerød from 1 June 2008 to 31 December 2013. | Procedure: Complete mesocolic excision<br>* The resection was based on the principles of CME. The superior mesenteric vein was exposed to perform central vessel ligation and lymph nodes dissection. Extended right hemicolectomies for tumors located from the ascending colon close to the hepatic flexure and distally were performed openly as standard during the study period. These resections included the prepyloric and gastroepiploic lymph nodes dissection.<br>|
| Non-CME group<br>The non-CME group comprised patients having a elective conventional colon cancer resection for right-sided adenocarcinoma at the other three colorectal centers in the Capital Region of Denmark from 1 June 2008 to 31 December 2013. | Procedure: Conventional colon resections<br>* The patients underwent what was considered standard colon cancer resections in Denmark during the study period.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Risk of recurrence | Recurrence diagnosed by CT or positron emission tomography (PET)/CT of thorax and abdomen, chest radiograph and contrast-enhanced ultrasound of the liver, or laparotomy in case of suspicion of recurrence. Histological verification of radiological findings of metastases during follow-up is not needed if the local multidisciplinary team conference deemed the finding as a recurrence. Metachronous colon tumors diagnosed during follow-up are considered as recurrences only if located in the anastomosis and with the same morphology as the primary tumor. | 5.2 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Overall survival | Death by any cause | 5.2 years | 
| Short-term mortality | Death from any cause within 30 and 90 days | 30 and 90 days | 
| Rate of postoperative complications | Patients having surgical and non-surgical postoperative complications and with complications with Clavien-Dindo score of 3b or more | 60 days | 
| Number of mesocolic lymph nodes | Median number and specimens with 22 or more lymph nodes detected | 1 day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Colon cancer, Surgery, Oncological outcome, Survival