This cohort study investigates the use of longitudinal data from ultradeep sequencing of cell-free DNA in Danish patients with colorectal cancer.

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Statement of translational relevanceSensitive methods for recurrence risk stratification, monitoring therapeutic efficacy, and early recurrence detection may have a major impact on treatment decisions and outcomes for stage III colorectal cancer patients. Circulating tumor DNA assessments performed postoperative, postadjuvant, and serially during surveillance all allowed stratification of patients into high and low risk groups. CtDNA detected recurrence with a significant leadtime compared to CT-imaging and ctDNA growth rates were prognostic of survival.Treatment of ctDNA positive patients with standard adjuvant therapy prevented recurrence in only 20% of patients. Accordingly, further studies exploring the optimal treatment for ctDNA positive patients are needed, as well as interventional studies assessing the clinical utility of ctDNA-based risk-stratification. A promising opportunity is risk-stratified allocation of surveillance resources, which may improve both the cost-effectiveness and the overall clinical outcome of surveillance. Finally, ctDNA growth rates may identify patients who could benefit from immediate therapeutic intervention compared to awaiting recurrence.Research.

Aim of databaseThe aim of the database, which has existed for registration of all patients with colorectal cancer in Denmark since 2001, is to improve the prognosis for this patient group.Study populationAll Danish patients with newly diagnosed colorectal cancer who are either diagnosed or treated in a surgical department of a public Danish hospital.Main variablesThe database comprises an array of surgical, radiological, oncological, and pathological variables. The surgeons record data such as diagnostics performed, including type and results of radiological examinations, lifestyle factors, comorbidity and performance, treatment including the surgical procedure, urgency of surgery, and intra- and postoperative complications within 30 days after surgery. The pathologists record data such as tumor type, number of lymph nodes and metastatic lymph nodes, surgical margin status, and other pathological risk factors.Descriptive dataThe database has had >95% completeness in including patients with colorectal adenocarcinoma with >54,000 patients registered so far with approximately one-third rectal cancers and two-third colon cancers and an overrepresentation of men among rectal cancer patients. The stage distribution has been more or less constant until 2014 with a tendency toward a lower rate of stage IV and higher rate of stage I after introduction of the national screening program in 2014. The 30-day mortality rate after elective surgery has been reduced from >7% in 2001–2003 to <2% since 2013.ConclusionThe database is a national population-based clinical database with high patient and data completeness for the perioperative period. The resolution of data is high for description of the patient at the time of diagnosis, including comorbidities, and for characterizing diagnosis, surgical interventions, and short-term outcomes. The database does not have high-resolution oncological data and does not register recurrences after primary surgery. The Danish Colorectal Cancer Group provides high-quality data and has been documenting an increase in short- and long-term survivals since it started in 2001 for both patients with colon and rectal cancers.

Emergency surgery for colonic cancer is still associated with an increased risk of death. There is a need for a system providing increased safety in the perioperative period.

Diagnostic laparoscopy was valuable in preoperative evaluation of the extent of peritoneal carcinomatosis, and improved patient selection for cytoreductive surgery and HIPEC.

Background The Danish Colorectal Cancer Group (DCCG) established a national clinical database in 2001 with the aim to monitor and improve outcome of colorectal cancer patients. Since 2000 several national initiatives have been taken to improve cancer outcome. In the present study we used DCCG data to evaluate mortality and survival of CRC patients with focus on comorbidity, stage, and perioperative treatment. Material and methods Patients notified to the DCCG database from 2001 to 2012 were included. Patients with primary cancer of the colon and rectum were analyzed separately. Analyses were stratified according to gender, comorbidity, Union for International Cancer Control (UICC) stage, and operative priority (elective/emergency/no surgery). Data were stratified into three time periods (2001-2004, 2005-2008, 2009-2012). Mortality and survival were age adjusted. Results In total 29 385 patients with colon cancer and 15 213 patients with rectal cancer were included. The stage distribution was almost stable over time. The mortality rate per 100 patient year within one year decreased from 32 to 26 in colon cancer and from 26 to 19 in rectal cancer with associated improvements in absolute survival from 73% to 78% in colon cancer and from 78% to 83% in rectal cancer. The five-year relative survival of colon cancer improved from 58% to 63% and in rectal cancer from 59% to 65%. Comorbidity had major negative impact on outcome. Irrespective of tumor location, outcome improved relatively more in patients with stage III and IV disease. The proportion of patients who were spared surgery increased from 8% to 15% in colon cancer and from 13% to 19% in rectal cancer, and these changes were associated with improved outcome for rectal cancer patients, whereas outcome worsened for colon cancer patients. Conclusion The Danish efforts to improve outcome of cancer have succeeded with improved outcomes in patients with colorectal cancer.