Surgical stress response and long-term survival in robot-assisted versus laparoscopic surgery for colon cancer: a propensity matched nationwide cohort study

PURPOSE

This study investigates the potential correlation between the surgical stress response and long-term survival in patients undergoing treatment for colon cancer using either RAS (robot-assisted surgery) or LAS (laparoscopic surgery) and whether this correlation is influenced by the surgical approach. The primary objective was to assess the association between postoperative C-reactive protein (CRP) response and recurrence-free survival in RAS compared with LAS. Secondary endpoints included all-cause mortality and time-to-recurrence.

METHODS

This Danish nationwide cohort study included patients diagnosed with Union for International Cancer Control (UICC) stage I-III colon cancer who underwent either RAS or LAS between 2010 and 2018. We employed the Cox proportional regression model to analyze the time-to-event outcomes for both primary and secondary endpoints in patients exhibiting either a low postoperative CRP response (< 80 mg/L) or a high CRP response (CRP ≥ 80 mg/L).

RESULTS

A total of 3484 patients were included in the study, with 490 (14.1%) undergoing RAS and 2994 (85.9%) undergoing LAS. The median follow-up time was 32.5 months (interquartile range [IQR] = 21.0-48.7) for the RAS group and 35.4 months (IQR = 22.8-50.9) for the LAS group. In the RAS group, a lower CRP response (CRP < 80 mg/L) was not associated with improved recurrence-free survival (HR = 0.78, 95% confidence interval [CI] [0.53-1.13], p = 0.184), all-cause mortality (hazard ratio [HR] = 0.76, 95% CI [0.46-1.26], p = 0.282), or time-to-recurrence (HR = 0.64, 95% CI [0.49-1.06], p = 0.079).

CONCLUSIONS

The postoperative CRP response was not significantly associated with improved long-term survival outcomes in patients undergoing RAS or LAS for UICC stage I-III colon cancer.

Proteomics of colorectal tumors identifies the role of CAVIN1 in tumor relapse

Colorectal cancer molecular signatures derived from omics data can be employed to stratify CRC patients and aid decisions about therapies or evaluate prognostic outcome. However, molecular biomarkers for identification of patients at increased risk of disease relapse are currently lacking. Here, we present a comprehensive multi-omics analysis of a Danish colorectal cancer tumor cohort composed of 412 biopsies from tumors of 371 patients diagnosed at TNM stage II or III. From mass spectrometry-based patient proteome profiles, we classified the tumors into four molecular subtypes, including a mesenchymal-like subtype. As the mesenchymal-rich tumors are known to represent the most invasive and metastatic phenotype, we focused on the protein signature defining this subtype to evaluate their potential as relapse risk markers. Among signature-specific proteins, we followed-up Caveolae-Associated Protein-1 (CAVIN1) and demonstrated its role in tumor progression in a 3D in vitro model of colorectal cancer. Compared to previous omics analyses of CRC, our multi-omics classification provided deeper insights into EMT in cancer cells with stronger correlations with risk of relapse.

Cancer recurrence risk with bDMARD treatment in patients with rheumatoid arthritis and a history of cancer: a nationwide Danish register-based cohort study

OBJECTIVE

To investigate the risk of cancer recurrence in patients with rheumatoid arthritis (RA) and a prior solid cancer in remission treated with biological disease-modifying antirheumatic drugs (bDMARDs) compared with those who received only conventional synthetic DMARDs (csDMARDs).

METHODS

Nationwide registry-based cohort study of Danish patients with RA and one of the six algorithm-specific solid cancers in remission (breast, colorectal, melanoma, bladder, endometrial and lung) who initiated treatment with a bDMARD or a csDMARD. Three bDMARD exposure groups were defined according to the type(s) of bDMARD initiated: (1) any bDMARD, (2) tumour necrosis factor inhibitors (TNFi) and (3) rituximab. Patients were identified in Danish Rheumatology Quality Register and followed for cancer recurrence from 2002 to 2021 using validated cancer-specific recurrence algorithms. Inverse probability of treatment weighting and weighted cause-specific Cox models were used to calculate HRs for cancer recurrence in each bDMARD exposure group compared with a csDMARD-treated group.

RESULTS

Among 720 unique patients with RA and an algorithm-specific solid cancer in remission, 170 any bDMARD, 81 TNFi, 99 rituximab and 651 csDMARD initiators were identified. No statistically significant increased HRs for cancer recurrence were found with any type of bDMARD 0.92 (95% CI 0.38 to 1.73), TNFi 1.10 (95% CI 0.21 to 3.16) or rituximab 0.94 (95% CI 0.32 to 2.11). Also, no increased HRs were shown for breast cancer recurrence specifically.

CONCLUSION

No indications of increased cancer recurrence risk were found for bDMARDs as used in clinical practice in patients with RA and a solid cancer in remission when compared with csDMARD treatment.

Major Adverse Cardiovascular Events After Colorectal Cancer Surgery, Oncological Outcomes, and Long-term Mortality: A Nationwide Retrospective Propensity Score-Matched Cohort Study

Objective

To investigate the occurrence of major adverse cardiovascular events (MACE) following colorectal cancer (CRC) surgery and its association with long-term mortality and oncological outcomes.

Background

Cardiovascular complications after noncardiac surgery are a leading cause of perioperative mortality. However, limited knowledge exists on how these complications impact on long-term mortality.

Methods

This retrospective cohort study used data from 4 nationwide Danish health registries and included all patients undergoing elective surgery with curative intent for CRC between 2001 and 2019. Patients experiencing MACE, defined as acute myocardial infarction, stroke, new-onset heart failure, or nonfatal cardiac arrest, within 30 days of surgery were matched with those who did not using 1:1 propensity score matching (PSM). The outcomes were all-cause mortality within 1, 3, or 5 years of surgery, as well as 5-year cancer recurrence and disease-free survival.

Results

Out of 39,747 patients, 900 (2.3%) had MACE. PSM resulted in 809 pairs of matched patients. Within 1 year of surgery, 110 (13.6%) patients with MACE and 2063 (5.4%) without MACE died (PSM-adjusted hazard ratio [HR] = 1.36; 95% confidence interval [CI] = 1.02-1.83). Within 3 years, 248 (30.6%) patients with MACE and 6268 (16.5%) without MACE died (PSM-adjusted HR = 1.32; 95% CI = 1.07-1.62). Within 5 years, 333 (41.1%) patients with MACE and 9232 (24.3%) without MACE died (PSM-adjusted HR = 1.25; 95% CI = 1.04-1.50). For recurrence and disease-free survival, no statistically significant differences were observed.

Conclusions

MACE within 30 days of CRC surgery is associated with higher overall long-term mortality. Investigating causality and preventive measures is urgent in this group.

Mismatch Repair Status and Surgical Outcomes in Localized Colorectal Cancer: A Nationwide Cohort Study

Objective

This study examined the association between deficient mismatch repair (dMMR) versus proficient MMR (pMMR) status and overall survival and disease-free survival in patients with localized colorectal cancer.

Background

Several distinctions exist between patients with dMMR and pMMR colorectal cancer. However, the impact on prognosis is yet to be investigated in large-scale cohort studies.

Methods

In this cohort study, we included patients who underwent curative-intent surgery for localized colorectal cancer between 2009 and 2020. Patients were identified in the Danish Colorectal Cancer Group database and patient-level data were extracted from 6 registry databases. After inclusion, patients with dMMR status were matched 1:1 to patients with pMMR status using an estimated propensity score.

Results

After matching, 5994 patients were included. The patients had a median age of 74 years and a median follow-up of 4.1 years. There was no significant association between mismatch repair (MMR) status and overall survival (hazard ratio, 0.91; 95% confidence interval [CI], 0.81-1.03) or disease-free survival (hazard ratio, 0.89; 95% CI, 0.78-1.01). However, the restricted 5-year mean disease-free survival time, calculated due to violation of the proportional hazards assumption, showed a significant absolute difference of 0.13 years (95% CI, 0.03-0.23; P = 0.01) in favor of the dMMR group.

Conclusions

No significant association with overall survival was found according to MMR status. dMMR status was, however, found to be associated with marginally improved disease-free survival compared to pMMR status in patients with localized colorectal cancer undergoing curative-intent surgery.

Risk of recurrence in early-onset versus late-onset non-metastatic colorectal cancer, 2004-2019: a nationwide cohort study

Background

The incidence of colorectal cancer (CRC) in individuals younger than 50 years of age (early-onset CRC) is increasing. Early-onset CRC often present at advanced stage, suggesting a more aggressive cancer course compared to late-onset CRC (age 50-79). This nationwide cohort study estimates the incidence of recurrence following early-onset CRC and late-onset CRC.

Methods

The study included all Danish patients <80 years old operated for first-time Union for International Cancer Control (UICC) stage I-III CRC between January 2004 and December 2019. Recurrence status was determined by applying a validated algorithm to individual-level data from nationwide health registries. The 5-year cumulative incidence functions (CIF) of recurrence were reported for early-onset versus late-onset CRC. The difference in time to recurrence was estimated as a time ratio (TR) using an accelerated failure time model.

Findings

Among 25,729 CRC patients, 1441 (5.6%) had early-onset CRC. Compared to late-onset CRC, early-onset was associated with advanced disease stages and higher treatment intensity. The 5-year CIF of recurrence was 29% (95% CI: 26%-31%) in early-onset versus 21% (95% CI: 21%-22%) in late-onset CRC. The higher CIF of recurrence for early-onset patients persisted in stage-stratified analysis. Time to recurrence was shorter in early-onset versus late-onset patients with TR = 0.76 (95% CI: 0.67-0.85). The 5-year CIF of recurrence decreased from 2004 to 2019 for both early- and late-onset patients-most prominent for early-onset patients.

Interpretation

Early-onset CRC was associated with higher incidence of recurrence at all disease stages. Indicating that the increased risk is not explained by delayed diagnosis. The excess risk diminished from 2004 to 2019, suggesting that early-onset CRC may achieve a similar recurrence risk as late-onset CRC in a contemporary setting.

Funding

Aarhus University, Novo Nordisk Foundation, Innovation Fund Denmark, and the Danish Cancer Society.

Validation of algorithms in studies based on routinely collected health data: general principles

Clinicians, researchers, regulators, and other decision-makers increasingly rely on evidence from real-world data (RWD), including data routinely accumulating in health and administrative databases. RWD studies often rely on algorithms to operationalize variable definitions. An algorithm is a combination of codes or concepts used to identify persons with a specific health condition or characteristic. Establishing the validity of algorithms is a prerequisite for generating valid study findings that can ultimately inform evidence-based health care. In this paper, we aim to systematize terminology, methods, and practical considerations relevant to the conduct of validation studies of RWD-based algorithms. We discuss measures of algorithm accuracy, gold/reference standards, study size, prioritization of accuracy measures, algorithm portability, and implications for interpretation. Information bias is common in epidemiologic studies, underscoring the importance of transparency in decisions regarding choice and prioritizing measures of algorithm validity. The validity of an algorithm should be judged in the context of a data source, and one size does not fit all. Prioritizing validity measures within a given data source depends on the role of a given variable in the analysis (eligibility criterion, exposure, outcome, or covariate). Validation work should be part of routine maintenance of RWD sources. This article is part of a Special Collection on Pharmacoepidemiology.

Associations between pre-operative cholesterol levels with long-term survival after colorectal cancer surgery: a nationwide propensity score-matched cohort study

PURPOSE

Altered lipid metabolism frequently occurs in patients with solid cancers and dyslipidemia has been associated with poorer outcomes in patients with colorectal cancer. This study sought to investigate whether cholesterol levels are associated with clinical outcomes and can serve as survival predictors.

METHODS

We conducted a retrospective cohort study with Danish patients diagnosed with colorectal cancer who had surgery with curative intent for UICC stages I to III between 2015 and 2020. Using propensity score adjustment, we matched patients in a 1:1 ratio to examine the impact of total cholesterol (TC) > 4 mmol/L vs. ≤ 4 mmol/L within 365 days prior to surgery on overall survival (OS) and disease-free survival (DFS).

RESULTS

A total of 3443 patients were included in the study. Median follow-up time was 3.8 years. Following propensity score matching, 1572 patients were included in the main analysis. There was no statistically significant difference in OS or DFS between patients with TC > 4 mmol/L compared with TC ≤ 4 mmol/L (HR: 0.82, 95% CI, 0.65-1.03, HR: 0.87, 95% CI, 0.68-1.12, respectively.). A subgroup analysis investigating TC > 4 mmol/L as well as low-density lipoprotein (LDL) > 3 mmol/L found a significant correlation with OS (HR: 0.74, 95% CI, 0.54-0.99).

CONCLUSION

TC levels alone were not associated with OS or DFS in patients with colorectal cancer. Interestingly, higher TC and LDL levels were linked to better overall survival, suggesting the need for further exploration of cholesterol's role in colorectal cancer.

TRIAL REGISTRATION

Not applicable.

The validity of pathology codes for biopsy-confirmed kidney disease in the Danish National Patobank

Background

This study validates the application of Systematized Nomenclature of Medicine second edition (SNOMED II) codes used to describe medical kidney biopsies in Denmark in encoded form, aiming to support robust epidemiological research on the causes, treatments and prognosis of kidney diseases.

Methods

Kidney biopsy reports from 1 January 1998 to 31 December 2018 were randomly extracted from the Danish National Patobank, using SNOMED codes. A 5% sample was selected, and nephrologists assessed the corresponding medical records, assigning each case the applied clinical diagnoses. Sensitivity, specificity, positive predictive values (PPV), negative predictive values and Cohen's kappa coefficient for the retrieved SNOMED codes were calculated.

Results

A total of 613 kidney biopsies were included. The primary clinical disease groups were glomerular disease (n = 368), tubulointerstitial disease (n = 67), renal vascular disease (n = 51), diabetic nephropathy (n = 51) and various renal disorders (n = 40). Several SNOMED codes were used to describe each clinical disease group and PPV for the combined SNOMED codes were high for glomerular disease (94%), diabetic nephropathy (85%) and systemic diseases affecting the kidney (96%). Conversely, tubulointerstitial disease (62%), renal vascular disease (60%) and other renal disorders (17%) showed lower PPV.

Conclusions

SNOMED codes have a high PPV for glomerular diseases, diabetic nephropathy and systemic diseases affecting the kidney, in which they could be applied for future epidemiological research.

Incidence of late recurrence and second primary cancers 5-10 years after non-metastatic colorectal cancer

The fraction of patients who are cancer-free survivors 5 years after curative-intended surgery for colorectal cancer (CRC) is increasing, suggesting that extending surveillance beyond 5 years may be indicated. Here we estimate the incidence of late recurrence, metachronous CRC, and second primary cancers 5-10 years postoperative. All patients resected for UICC stage I-III CRC in Denmark through 2004-2013 were identified. Through individual-level linkage of nationwide health registry data, recurrence status was determined using a validated algorithm. Cancer-free survivors 5 years after surgery, were included. Cumulative incidence functions (CIF) of late recurrence, metachronous CRC, and second primary cancer 5-10 years postoperative were constructed. Subdistribution hazards ratios (sHR) were computed using Fine-Gray regression. Among 8883 patients, 370 developed late recurrence (5-10-year CIF = 4.1%, 95%CI: 3.7%-4.6%), 270 metachronous CRC (5-10-year CIF = 3.0%, 95%CI: 2.7%-3.4%), and 635 a second primary cancer (5-10-year CIF = 7.2%, 95%CI: 6.7%-7.7%). The risk of late recurrence was reduced for patients operated in 2009-2013 compared to 2004-2008 (2.9% vs. 5.6%, sHR = 0.52, 95% CI: 0.42-0.65). The risk of metachronous CRC was likewise reduced from 4.1% to 2.1% (sHR = 0.50, 95%CI: 0.39-0.65). While the risk of second primary cancer did not change between 2009-2013 and 2004-2008 (7.1% vs. 7.1%, sHR = 0.98, 95% CI: 0.84-1.15). Using nation-wide 10-year follow-up data, we document that the incidences of late recurrence and metachronous CRC are low and decreasing from 2004 to 2013. Thus, despite increasing numbers of long-term cancer survivors, the data do not advocate for extending CRC-specific surveillance beyond 5 years.

Correlations between preoperative statin treatment with short- and long-term survival following colorectal cancer surgery: a propensity score-matched national cohort study

INTRODUCTION

The pleiotropic effects of statins have attracted considerable attention in oncological treatment. Several preclinical and epidemiological studies have highlighted their potential anti-tumor properties in patients with colorectal cancer, although results have been conflicting. This study aimed to examine the association between statin exposure before colorectal cancer surgery with long and short-term survival outcomes.

METHODS

This retrospective propensity score-adjusted study was conducted on a Danish cohort of patients who underwent elective curative-intended surgery for stage I-III colorectal cancer in 2008-2020, using four national patient databases. The primary and secondary outcomes were overall, 90-day, and disease-free survival. Propensity scores were calculated using all available data to match patients with and without statin exposure in a 1:1 ratio.

RESULTS

Following propensity score matching, 7120 patients were included in the primary analysis. The median follow-up time was 5 years. A Cox proportional hazards model showed no statistically significant difference in overall survival between patients with or without statin exposure 365 days before surgery (HR 0.93, 95% CI 0.85-1.02) and no association with 90-day survival (OR 0.91, 95% CI 0.76-1.10). However, a subgroup analysis examining a 90-day exposure before surgery found a statistically significant association with increased overall survival (HR 0.85, 95% CI 0.77-0.93).

CONCLUSION

Although a subgroup of patients with a preoperative exposure time of 90 days showed statistically significant better overall survival, we found no statistically significant association between statin exposure 1 year before colorectal cancer surgery and overall survival.

Long-term Outcomes of Robot-assisted Versus Laparoscopic Surgery for Colon Cancer: A Nationwide Register-based Cohort Study

OBJECTIVE

To determine long-term survival in patients undergoing robot-assisted surgery (RAS) or laparoscopic surgery (LAS) for colon cancer.

BACKGROUND

The potential long-term benefits of RAS compared with LAS for colon cancer are not well examined. Using a register-based approach, we aimed to compare these 2 surgical platforms in an analysis of long-term outcomes, including recurrence-free survival and all-cause- and colon cancer-specific mortality.

METHODS

A nationwide register-based cohort study of patients with Union for International Cancer Control stage I-III colon cancer undergoing planned RAS or LAS from 2010 through 2018. Patient demographic, clinical, and pathological data were retrieved from Danish national registers. Survival and recurrence rates were estimated by Cox proportional hazard multivariate regression analysis adjusting for baseline covariates.

RESULTS

A total of 7565 patients [LAS=6905 (91%) and RAS=660 (9%)] were included in the complete case survival analysis. Patients undergoing LAS had a significantly increased risk of cancer recurrence [LAS=1178 (17.1%), RAS=82 (12.4%), P =0.002] with a mean follow-up time of 4.93 years (standard deviation 2.47). The survival analysis of recurrence-free survival favored RAS [hazard ratio adjusted =0.80, 95% CI (0.64-1.00), P =0.049]. No associations between the 2 surgical platforms were evident regarding all-cause [hazard ratio adjusted =0.98, 95% CI (0.82-1.17), P =0.783] or colon cancer-specific mortality [hazard ratio adjusted =0.89, 95% CI (0.67-1.18), P =0.405].

CONCLUSIONS

Adopting RAS for colon cancer was associated with improved recurrence-free survival. However, it did not cause a lower all-cause- or colon cancer-specific mortality.

Development of an Automatic Rule-Based Algorithm for the Detection of Ovarian Cancer Recurrence From Electronic Health Records

PURPOSE

As the onset of cancer recurrence is not explicitly recorded in the electronic health record (EHR), a high volume of manual chart review is required to detect the cancer recurrence. This study aims to develop an automatic rule-based algorithm for detecting ovarian cancer (OC) recurrence on the basis of minimally preprocessed EHR data.

METHODS

The automatic rule-based recurrence detection algorithm (Auto-Recur), using notes on image reading (positron emission tomography-computed tomography [PET-CT], CT, magnetic resonance imaging [MRI]), biomarker (CA125), and treatment information (surgery, chemotherapy, radiotherapy), was developed to detect the first OC recurrence. Auto-Recur contains three single algorithms (images, biomarkers, treatments) and hybrid algorithms (combinations of the single algorithms). The performance of Auto-Recur was assessed using sensitivity, specificity, and accuracy of the recurrence time detected. The recurrence-free survival probabilities were estimated and compared with the retrospective chart review results.

RESULTS

The proposed Auto-Recur considerably reduced human resources and time; it saved approximately 1,340 days when scaled to 100,000 patients compared with the conventional retrospective chart review. The hybrid algorithm on the basis of a combination of image, biomarker, and treatment information was the most efficient (sensitivity: 93.4%, specificity: 97.4%) and precisely captured recurrence time (average time error: 8.5 days). The estimated 3-year recurrence-free survival probability (44%) was close to the estimates by the retrospective chart review (45%, log-rank P value = .894).

CONCLUSION

Our rule-based algorithm effectively captured the first OC recurrence from large-scale EHR while closely approximating the recurrence-free survival estimates obtained by conventional retrospective chart reviews. The study findings facilitate large-scale EHR analysis, enhancing clinical research opportunities.

Preoperative intravenous iron treatment - a cohort study on colorectal cancer recurrence

BACKGROUND

Intravenous (i.v.) iron treatment has been speculated to increase the malignant potential of colorectal malignancies but also to enhance the immune systems potential to fight the invasive tumor. Clinical data however is very limited. We investigate if preoperative i.v. iron treatment is associated with colorectal cancer (CRC) recurrence.

METHODS

Retrospective cohort study on surgical CRC patients with iron deficiency anemia (1st March 2013 - 31st December 2019). Patients were grouped based on whether they had received preoperative treatment with i.v. iron. Local data was combined with data from the National Danish Health registries to identify recurrences, death, and emigration. Survival analysis, including Kaplan-Meyer curves and multivariate competing risk analysis adjusting for sex, age, ASA-group, tumor stage, surgical radicality, and miss match repair status was performed.

RESULTS

Of 1228 patients, 125 were available for analysis. 89 patients had received preoperative i.v. iron and 36 had not. The two groups were comparable on baseline and surgical characteristics. Median follow-up times were 4.74 in iron treated patients and 5 years in patients not receiving iron treatment. Five-year rate of non-recurrence was 85 % (0.74-0.91) in the i.v. iron treated group vs. 82 % (0.64-0.91) in the control group, non-significant difference. Multivariate survival analysis did not find iron treatment to be associated with recurrence rates (Hazard Ratio 0.88 (95 % ci; 0.31-2.51).

CONCLUSION

No association between preoperative i.v. iron treatment and the five-year cancer recurrence rate in iron deficient anemic CRC patients was found.

Improving communication of cancer survival statistics-feasibility of implementing model-based algorithms in routine publications

BACKGROUND

Routine reporting of cancer patient survival is important, both to monitor the effectiveness of health care and to inform about prognosis following a cancer diagnosis. A range of different survival measures exist, each serving different purposes and targeting different audiences. It is important that routine publications expand on current practice and provide estimates on a wider range of survival measures. We examine the feasibility of automated production of such statistics.

METHODS

We used data on 23 cancer sites obtained from the Cancer Registry of Norway (CRN). We propose an automated way of estimating flexible parametric relative survival models and calculating estimates of net survival, crude probabilities, and loss in life expectancy across many cancer sites and subgroups of patients.

RESULTS

For 21 of 23 cancer sites, we were able to estimate survival models without assuming proportional hazards. Reliable estimates of all desired measures were obtained for all cancer sites.

DISCUSSION

It may be challenging to implement new survival measures in routine publications as it can require the application of modeling techniques. We propose a way of automating the production of such statistics and show that we can obtain reliable estimates across a range of measures and subgroups of patients.

The impact of time to surgery on oncological outcomes in stage I-III dMMR colon cancer - A nationwide cohort study

INTRODUCTION

One of the considerations when investigating neoadjuvant interventions is the prolonging of time from diagnosis to curative surgery (i.e. the treatment interval [TI]). The aim of this study was to investigate the association between the length of TI and overall survival and disease-free survival in patients with deficient mismatch repair (dMMR) colon cancer.

MATERIALS AND METHODS

This retrospective propensity score-adjusted study included all patients of ≥18 years of age undergoing elective curative surgery for stage I-III, dMMR colon cancer. Data were extracted from four Danish patient databases. Outcomes were investigated in groups with TIs of ≤14 days versus >14 days. Propensity scores were computed using all demographics, diagnoses and measurements. Matching was done in a 1:1 ratio.

RESULTS

A total of 4130 patients were included in the study with a mean age of 73.8 years and a median follow-up time of 43.9 months. After matching, 2794 patients were included in the analysis of overall survival. No significant difference in overall survival was seen between patients with TIs of ≤14 days versus >14 days (hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.81-1.17; p = 0.78). In the analysis of disease-free survival, 1798 patients were included after matching. This showed no significant difference between patients with TIs of ≤14 days versus >14 days (HR, 0.85; 95% CI, 0.69-1.06; p = 0.14).

CONCLUSION

No associations were found between TI and overall survival and disease-free survival in patients with stage I-III, dMMR colon cancer undergoing elective curative surgery.

Cardiovascular events after elective colorectal cancer surgery in patients with stage I-III disease with no previous cardiovascular disease

BACKGROUND

The risk of cardiovascular events in patients treated for colorectal cancer is debated due to diverging results in previous studies. Colorectal cancer and cardiovascular disease share several risk factors such as physical inactivity, obesity, and smoking. Information about confounding covariates and follow-up time are therefore essential to address the issue. This study aims to investigate the risk of new-onset cardiovascular events for patients with stage I-III colorectal cancer receiving elective surgery compared to a matched population.

MATERIAL AND METHODS

Using a prospective cohort, we compared cardiovascular events among 876 patients treated with elective surgery for incident stage I-III colorectal cancer diagnosed between January 1st, 2001 and December 31st, 2016 to a cancer-free cohort matched by age, sex, and time since enrollment (N = 3504). Regression analyses were adjusted for lifestyle, cardiovascular risk factors, and comorbidity. Multivariable analyses were used to identify risk factors associated with cardiovascular events in the postoperative (<90 days of elective surgery) and long-term phase (>90 days after elective surgery).

RESULTS

After a median follow-up of 3.9 years, the hazard ratio (HR) for incident heart failure was 1.53 (95% CI 1.02-2.28) among patients operated for colorectal cancer. The postoperative risk of myocardial infarction or angina pectoris was associated with the use of lipid-lowering drugs. Long-term risks of cardiovascular events were ASA-score of III+IV and lipid-lowering drugs with HRs ranging from 2.20 to 15.8. Further, the use of antihypertensive drugs was associated with an HR of 2.09 (95% CI 1.06-4.13) for angina pectoris or acute myocardial infarction. Heart failure was associated with being overweight, diabetes, and anastomosis leakage.

CONCLUSION

We observed an increased hazard of heart failure in patients operated on for stage I-III colorectal cancer compared to cancer-free comparisons. We identified several potential risk factors for cardiovascular events within and beyond 90 days of elective surgery.

Identifying Recurrences Among Non-Metastatic Colorectal Cancer Patients Using National Health Data Registries: Validation and Optimization of a Registry-Based Algorithm in a Modern Danish Cohort

Purpose

Colorectal cancer (CRC) recurrence is not routinely recorded in Danish health data registries. Here, we aimed to revalidate a registry-based algorithm to identify recurrences in a contemporary cohort and to investigate the accuracy of estimating the time to recurrence (TTR).

Patients and Methods

We ascertained data on 1129 patients operated for UICC TNM stage I-III CRC during 2012-2017 registered in the CRC biobank at the Department of Molecular Medicine, Aarhus University Hospital, Denmark. Individual-level data were linked with data from the Danish Colorectal Cancer Group database, Danish Cancer Registry, Danish National Registry of Patients, and Danish Pathology Registry. The algorithm identified recurrence based on diagnosis codes of local recurrence or metastases, the receipt of chemotherapy, or a pathological tissue assessment code of recurrence more than 180 days after CRC surgery. A subgroup was selected for validation of the algorithm using medical record reviews as a reference standard.

Results

We found a 3-year cumulative recurrence rate of 20% (95% CI: 17-22%). Manual medical record review identified 80 recurrences in the validation cohort of 522 patients. The algorithm detected recurrence with 94% sensitivity (75/80; 95% CI: 86-98%) and 98% specificity (431/442; 95% CI: 96-99%). The positive and negative predictive values of the algorithm were 87% (95% CI: 78-93%) and 99% (95% CI: 97-100%), respectively. The median difference in TTR (TTR_{Medical_chart}-TTR_algorithm) was -8 days (IQR: -21 to +3 days). Restricting the algorithm to chemotherapy codes from oncology departments increased the positive predictive value from 87% to 94% without changing the negative predictive value (99%).

Conclusion

The algorithm detected recurrence and TTR with high precision in this contemporary cohort. Restriction to chemotherapy codes from oncology departments using department classifications improves the algorithm. The algorithm is suitable for use in future observational studies.

A Validated Algorithm for Register-Based Identification of Patients with Relapse of Clinical Stage I Testicular Cancer

Purpose

The Danish Testicular Cancer (DaTeCa) database aims to monitor and improve quality of care for testicular cancer patients. Relapse data registered in the DaTeCa database rely on manual registration. Currently, some safeguarding against missing registrations is attempted by a non-validated register-based algorithm. However, this algorithm is inaccurate and entails time-consuming medical record reviews. We aimed (1) to validate relapse data as registered in the DaTeCa database, and (2) to develop and validate an improved register-based algorithm identifying patients diagnosed with relapse of clinical stage I testicular cancer.

Patients and Methods

Patients registered in the DaTeCa database with clinical stage I testicular cancer from 2013 to 2018 were included. Medical record information on relapse data served as a gold standard. A pre-specified algorithm to identify relapse was tested and optimized on a random sample of 250 patients. Indicators of relapse were obtained from pathology codes in the Danish National Pathology Register and from diagnosis and procedure codes in the Danish National Patient Register. We applied the final algorithm to the remaining study population to validate its performance.

Results

Of the 1377 included patients, 284 patients relapsed according to the gold standard during a median follow-up time of 5.9 years. The completeness of relapse data registered in the DaTeCa database was 97.2% (95% confidence interval (CI): 95.2-99.1). The algorithm achieved a sensitivity of 99.6% (95% CI: 98.7-100), a specificity of 98.9% (95% CI: 98.2-99.6), and a positive predictive value of 95.9% (95% CI: 93.4-98.4) in the validation cohort (n = 1127, 233 relapses).

Conclusion

The registration of relapse data in the DaTeCa database is accurate, confirming the database as a reliable source for ongoing clinical quality assessments. Applying the provided algorithm to the DaTeCa database will optimize the accuracy of relapse data further, decrease time-consuming medical record review and contribute to important future clinical research.

A Validated Register-Based Algorithm to Identify Patients Diagnosed with Recurrence of Surgically Treated Stage I Lung Cancer in Denmark

Introduction

Recurrence of cancer is not routinely registered in Danish national health registers. This study aimed to develop and validate a register-based algorithm to identify patients diagnosed with recurrent lung cancer and to estimate the accuracy of the identified diagnosis date.

Material and Methods

Patients with early-stage lung cancer treated with surgery were included in the study. Recurrence indicators were diagnosis and procedure codes recorded in the Danish National Patient Register and pathology results recorded in the Danish National Pathology Register. Information from CT scans and medical records served as the gold standard to assess the accuracy of the algorithm.

Results

The final population consisted of 217 patients; 72 (33%) had recurrence according to the gold standard. The median follow-up time since primary lung cancer diagnosis was 29 months (interquartile interval: 18-46). The algorithm for identifying a recurrence reached a sensitivity of 83.3% (95% CI: 72.7-91.1), a specificity of 93.8% (95% CI: 88.5-97.1), and a positive predictive value of 87.0% (95% CI: 76.7-93.9). The algorithm identified 70% of the recurrences within 60 days of the recurrence date registered by the gold standard method. The positive predictive value of the algorithm decreased to 70% when the algorithm was simulated in a population with a recurrence rate of 15%.

Conclusion

The proposed algorithm demonstrated good performance in a population with 33% recurrences over a median of 29 months. It can be used to identify patients diagnosed with recurrent lung cancer, and it may be a valuable tool for future research in this field. However, a lower positive predictive value is seen when applying the algorithm in populations with low recurrence rates.

Validated algorithms for identifying timing of second event of oropharyngeal squamous cell carcinoma using real-world data

BACKGROUND

Understanding occurrence and timing of second events (recurrence and second primary cancer) is essential for cancer specific survival analysis. However, this information is not readily available in administrative data.

METHODS

Alberta Cancer Registry, physician claims, and other administrative data were used. Timing of second event was estimated based on our developed algorithm. For validation, the difference, in days between the algorithm estimated and the chart-reviewed timing of second event. Further, the result of Cox-regression modeling cancer-free survival was compared to chart review data.

RESULTS

Majority (74.3%) of the patients had a difference between the chart-reviewed and algorithm-estimated timing of second event falling within the 0-60 days window. Kaplan-Meier curves generated from the estimated data and chart review data were comparable with a 5-year second-event-free survival rate of 75.4% versus 72.5%.

CONCLUSION

The algorithm provided an estimated timing of second event similar to that of the chart review.

Long-term oncological outcomes in patients undergoing laparoscopic versus open surgery for colon cancer: A nationwide cohort study

AIM

To estimate the effect of laparoscopy versus laparotomy on recurrence status in patients undergoing intended curative resection for stage I-III colon cancer using nationwide data.

METHOD

A retrospective cohort study using prospectively collected nationwide quality assurance data on all patients undergoing elective, intended curative surgery for UICC stage I-III colon cancer in Denmark from 1 January 2010, through 31 December 2013. The association between laparoscopic versus open surgery and recurrence status was investigated using cause-specific hazard and subdistribution hazard models with death from any cause as a competing event.

RESULTS

In total, 4369 patients undergoing elective intended curative surgery for colon cancer were included in the analysis. Overall, 3243 (74.2%) patients underwent laparoscopic surgery. During a median follow-up time of 84 months, 1191 (27.2%) patients experienced recurrence, and 1304 (29.8%) patients died. The cause-specific hazard of recurrence following laparoscopic versus open surgery was HR_CS  = 1.08, 95% CI: 0.90-1.28, p = 0.422. The subdistribution hazard of recurrence following laparoscopic versus open surgery was HR_SD =0.99, 95% CI: 0.84-1.16, p = 0.880.

CONCLUSION

Elective laparoscopic resection for UICC stage I-III colon cancer is oncologically safe and comparable with open resection. These results confirm the external validity of previous RCTs in everyday clinical settings.

Epidural Analgesia and Recurrence after Colorectal Cancer Surgery: A Danish Retrospective Registry-based Cohort Study

BACKGROUND

Surgery is the main curative treatment for colorectal cancer. Yet the immunologic and humoral response to surgery may facilitate progression of micro-metastases. It has been suggested that epidural analgesia preserves immune competency and prevents metastasis formation. Hence, the authors tested the hypothesis that epidural analgesia would result in less cancer recurrence after colorectal cancer surgery.

METHODS

The Danish Colorectal Cancer Group Database and the Danish Anesthesia Database were used to identify patients operated for colorectal cancer between 2004 and 2018 with no residual tumor tissue left after surgery. The exposure group was defined by preoperative insertion of an epidural catheter for analgesia. The primary outcome was colorectal cancer recurrence, and the secondary outcome was mortality. Recurrences were identified using a validated algorithm based on data from Danish health registries. Follow-up was until death or September 7, 2018. The authors used propensity score matching to adjust for potential preoperative confounders.

RESULTS

In the study population of 11,618 individuals, 3,496 (30.1%) had an epidural catheter inserted before surgery. The epidural analgesia group had higher proportions of total IV anesthesia, laparotomies, and rectal tumors, and epidural analgesia was most frequently used between 2009 and 2012. The propensity score-matched study cohort consisted of 2,980 individuals in each group with balanced baseline covariates. Median follow-up was 58 months (interquartile range, 29 to 86). Recurrence occurred in 567 (19.0%) individuals in the epidural analgesia group and 610 (20.5%) in the group without epidural analgesia. The authors found no association between epidural analgesia and recurrence (hazard ratio, 0.91; 95% CI, 0.82 to 1.02) or mortality (hazard ratio, 1.01; 95% CI, 0.92 to 1.10).

CONCLUSIONS

In colorectal cancer surgery, epidural analgesia was not statistically significantly associated with less cancer recurrence.

EDITOR’S PERSPECTIVE

Association of influenza vaccine and risk of recurrence in patients undergoing curative surgery for colorectal cancer

BACKGROUND

There is increasing evidence that the inactivated influenza vaccine contains immunostimulatory properties that favor cytotoxicity and benefit survival in large population-based studies. This study aimed to determine whether an influenza vaccine was associated with risk of recurrence, overall mortality, and disease-free survival in patients undergoing curative surgery for colorectal cancer.

MATERIAL AND METHODS

We performed a register-based study based in Denmark in the period 2009-2015. The primary outcome was a risk of recurrence, while the secondary outcomes were overall mortality and disease-free survival.

RESULTS

A total of 9869 patients were included, with 5146 patients receiving an influenza vaccine between one year before and six months after surgery. In a multivariate Cox regression model, there was no association with risk of recurrence (HR 0.94, 95% CI 0.85-1.05), overall mortality (HR 0.95, 95% CI 0.87-1.03), and disease-free survival (HR 1.01, 95% CI 0.94-1.09). In patients receiving the vaccine between six and twelve months before surgery, we found an association to decreased risk of recurrence (HR 0.78, 95% CI 0.67-0.91) but no association with overall mortality (HR 1.04, 95% CI 0.93-1.17) or disease-free survival (HR 0.97, 95% CI 0.88-1.07). Subgroup analysis of patients revealed contradictory results.

CONCLUSION

We believe that this study's findings support the need for further clinical studies to investigate the causal effects of the influenza vaccine on oncological outcomes.

Long-Term Outcomes After Colorectal Surgery in Patients with Ulcerative Colitis-Associated Colorectal Cancer Versus Sporadic Colorectal Cancer

BACKGROUND

Ulcerative colitis is associated with a higher risk for developing colorectal cancer. It is unknown whether this translates into a worse prognosis when malignancy occurs. The goal of this study was to compare long-term outcomes between patients with ulcerative colitis-associated colorectal cancer and sporadic colorectal cancer.

METHODS

All patients who underwent surgery with curative intent for colorectal cancer in Denmark between January 2004 and June 2016 were included in the study. Patients diagnosed with ulcerative colitis were identified and matched 1:5 with patients with sporadic colorectal cancer using propensity score matching. The primary outcome was disease-free survival, with recurrence-free survival and all-cause mortality as secondary outcomes. In order to relate the results of the study to the existing literature, a systematic review with meta-analysis was conducted.

RESULTS

A total of 1332 patients, 222 with ulcerative colitis and 1110 with sporadic colorectal cancer were included in the study. Disease-free survival was similar between the two groups with a hazards ratio (HR) 1.06 [95% confidence interval (CI) 0.85-1.32], as was recurrence-free survival HR 1.14 (95% CI 0.86-1.53) and all-cause mortality HR 1.15 (95% CI 0.89-1.48). The results of the systematic review identified seven other relevant studies. Meta-analysis showed a HR 1.67 (95% CI 0.61-4.56) for recurrence-free survival and HR 1.21 (95% CI 0.93-1.56) for all-cause mortality.

CONCLUSIONS

There were no significant differences in long-term outcomes between ulcerative colitis-associated and sporadic colorectal cancer. However, the current results are limited by possible residual confounding and the meta-analysis by heterogeneity in confounding adjustment.

Identification of endometrial cancer recurrence - a validated algorithm based on nationwide Danish registries

INTRODUCTION

Recurrence of endometrial cancer is not routinely registered in the Danish national health registers. The aim of this study was to develop and validate a register-based algorithm to identify women diagnosed with endometrial cancer recurrence in Denmark to facilitate register-based research in this field.

MATERIAL AND METHODS

We conducted a cohort study based on data from Danish health registers. The algorithm was designed to identify women with recurrence and estimate the accompanying diagnosis date, which was based on information from the Danish National Patient Registry and the Danish National Pathology Registry. Indicators of recurrence were pathology registrations and procedure or diagnosis codes suggesting recurrence and related treatment. The gold standard for endometrial cancer recurrence originated from a Danish nationwide study of 2612 women diagnosed with endometrial cancer, FIGO stage I-II during 2005-2009. Recurrence was suspected in 308 women based on pathology reports, and recurrence suspicion was confirmed or rejected in the 308 women based on reviews of the medical records. The algorithm was validated by comparing the recurrence status identified by the algorithm and the recurrence status in the gold standard.

RESULTS

After relevant exclusions, the final study population consisted of 268 women, hereof 160 (60%) with recurrence according to the gold standard. The algorithm displayed a sensitivity of 91.3% (95% confidence interval (CI): 85.8-95.1), a specificity of 91.7% (95% CI: 84.8-96.1) and a positive predictive value of 94.2% (95% CI: 89.3-97.3). The algorithm estimated the recurrence date within 30 days of the gold standard in 86% and within 60 days of the gold standard in 94% of the identified patients.

DISCUSSION

The algorithm demonstrated good performance; it could be a valuable tool for future research in endometrial cancer recurrence and may facilitate studies with potential impact on clinical practice.

A Validated Register-Based Algorithm to Identify Patients Diagnosed with Recurrence of Malignant Melanoma in Denmark

Purpose

Information on cancer recurrence is rarely available outside clinical trials. Wide exclusion criteria used in clinical trials tend to limit the generalizability of findings to the entire population of people living beyond a cancer disease. Therefore, population-level evidence is needed. The aim of this study was to develop and validate a register-based algorithm to identify patients diagnosed with recurrence after curative treatment of malignant melanoma.

Patients and Methods

Indicators of recurrence were diagnosis and procedure codes recorded in the Danish National Patient Register and pathology results recorded in the Danish National Pathology Register. Medical records on recurrence status and recurrence date in the Danish Melanoma Database served as the gold standard to assess the accuracy of the algorithm.

Results

The study included 1747 patients diagnosed with malignant melanoma; 95 (5.4%) were diagnosed with recurrence of malignant melanoma according to the gold standard. The algorithm reached a sensitivity of 93.7% (95% confidence interval (CI) 86.8–97.6), a specificity of 99.2% (95% CI: 98.6–99.5), a positive predictive value of 86.4% (95% CI: 78.2–92.4), and negative predictive value of 99.6% (95% CI: 99.2–99.9). Lin’s concordance correlation coefficient was 0.992 (95% CI: 0.989–0.996) for the agreement between the recurrence dates generated by the algorithm and by the gold standard.

Conclusion

The algorithm can be used to identify patients diagnosed with recurrence of malignant melanoma and to establish the timing of recurrence. This can generate population-level evidence on disease-free survival and diagnostic pathways for recurrence of malignant melanoma.

Inhalation or total intravenous anaesthesia and recurrence after colorectal cancer surgery: a propensity score matched Danish registry-based study

BACKGROUND

During colorectal cancer surgery, the immune-modulating effects of inhalation anaesthesia may create a favourable environment for metastasis formation, leading to increased risk of recurrence. Our aim was to assess the association between inhalation vs intravenous anaesthesia and cancer recurrence in patients undergoing colorectal cancer surgery.

METHODS

Patients undergoing colorectal cancer surgery in 2004-18 were identified in the Danish Colorectal Cancer Group Database and Danish Anaesthesia Database. After exclusion of patients with residual tumour registered in postoperative pathology reports, local endoscopic resections, and stent insertions, we classified patients according to exposure to inhalation anaesthesia. The primary outcome was recurrence (time to recurrence), whereas secondary outcomes were all-cause mortality (time to death) and disease-free survival (time to either recurrence or death). Events of recurrence and death were identified using The Danish Civil Registration System, Danish National Pathology Registry, and Danish National Patient Registry. The sub-distribution hazards approach was used to estimate hazard ratios (HRs) for recurrence, and Cox regression was used for all-cause mortality and disease-free survival.

RESULTS

We identified 5238 patients exposed to inhalation anaesthesia and 6322 to intravenous anaesthesia. Propensity score matching yielded 4347 individuals in each group with balanced baseline covariates. We found a weak association between recurrence and exposure to inhalation anaesthesia (HR=1.12; 95% confidence interval [CI], 1.02-1.23). The HR estimates for all-cause mortality and disease-free survival were 1.00 (95% CI, 0.93-1.07) and 1.04 (95% CI, 0.98-1.11) respectively.

CONCLUSION

Exposure to inhalation anaesthesia was associated with increased risk of recurrence after colorectal cancer surgery.

Estimating Population-Based Recurrence Rates of Colorectal Cancer over Time in the United States

BACKGROUND

Population-based metastatic recurrence rates for patients diagnosed with nonmetastatic colorectal cancer cannot be estimated directly from population-based cancer registries because recurrence information is not reported. We derived population-based colorectal cancer recurrence rates using disease-specific survival data based on our understanding of the colorectal cancer recurrence-death process.

METHODS

We used a statistical continuous-time multistate survival model to derive population-based annual colorectal cancer recurrence rates from 6 months to 10 years after colorectal cancer diagnosis using relative survival data from the Surveillance, Epidemiology, and End Results Program. The model was based on the assumption that, after 6 months of diagnosis, all colorectal cancer-related deaths occur only in patients who experience a metastatic recurrence first, and that the annual colorectal cancer-specific death rate among patients with recurrence was the same as in those diagnosed with de novo metastatic disease. We allowed recurrence rates to vary by post-diagnosis time, age, stage, and location for two diagnostic time periods.

RESULTS

In patients diagnosed in 1975-1984, annual recurrence rates 6 months to 5 years after diagnosis ranged from 0.054 to 0.060 in stage II colon cancer, 0.094 to 0.105 in stage II rectal cancer, and 0.146 to 0.177 in stage III colorectal cancer, depending on age. We found a statistically significant decrease in colorectal cancer recurrence among patients diagnosed in 1994-2003 compared with those diagnosed in 1975-1984 for 6 months to 5 years after diagnosis (hazard ratios between 0.43 and 0.70).

CONCLUSIONS

We derived population-based annual recurrence rates for up to 10 years after diagnosis using relative survival data.

IMPACT

Our estimates can be used in decision-analytic models to facilitate analyses of colorectal cancer interventions that are more generalizable.

Validation of an Algorithm to Ascertain Late Breast Cancer Recurrence Using Danish Medical Registries

Purpose

About 70% of women with breast cancer survive at least 10 years after diagnosis. We constructed an algorithm to ascertain late breast cancer recurrence—which we define as breast cancer that recurs 10 years or more after primary diagnosis (excluding contralateral breast cancers)—using Danish nationwide medical registries. We used clinical information recorded in medical records as a reference standard.

Methods

Using the Danish Breast Cancer Group clinical database, we ascertained data on 21,134 women who survived recurrence-free 10 years or more after incident stage I–III breast cancer diagnosed in 1987–2004. We used a combination of Danish registries to construct the algorithm—the Danish National Patient Registry for information on diagnostic, therapeutic and procedural codes; and cancer diagnoses from the Danish Pathology Registry, the Danish Cancer Registry and the Contralateral Breast Cancer database. To estimate the positive predictive value (PPV), we selected 105 patients who, according to our algorithm, had late recurrence diagnosed at Aarhus University Hospital. To estimate the sensitivity, specificity and negative predictive value (NPV), we selected 114 patients diagnosed with primary breast cancer at Aalborg University Hospital. We abstracted clinical information on late recurrence for patients with medical record-confirmed late recurrence at Aarhus University Hospital.

Results

Our algorithm had a PPV of late recurrence of 85.7% (95% CI: 77.5–91.3%), a sensitivity of 100.0% (95% CI, 39.8–100.0%), a specificity of 97.3 (95% CI, 92.2–99.4) and a NPV of 100% (95% CI, 96.6–100.0%).

Conclusion

Our algorithm for late recurrence showed a moderate to high PPV and high sensitivity, specificity and negative predictive value. The algorithm could be an important tool for future studies of late breast cancer recurrence.

A Systematic Review of Estimating Breast Cancer Recurrence at the Population Level With Administrative Data

BACKGROUND

Exact numbers of breast cancer recurrences are currently unknown at the population level, because they are challenging to actively collect. Previously, real-world data such as administrative claims have been used within expert- or data-driven (machine learning) algorithms for estimating cancer recurrence. We present the first systematic review and meta-analysis, to our knowledge, of publications estimating breast cancer recurrence at the population level using algorithms based on administrative data.

METHODS

The systematic literature search followed Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. We evaluated and compared sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of algorithms. A random-effects meta-analysis was performed using a generalized linear mixed model to obtain a pooled estimate of accuracy.

RESULTS

Seventeen articles met the inclusion criteria. Most articles used information from medical files as the gold standard, defined as any recurrence. Two studies included bone metastases only in the definition of recurrence. Fewer studies used a model-based approach (decision trees or logistic regression) (41.2%) compared with studies using detection rules without specified model (58.8%). The generalized linear mixed model for all recurrence types reported an accuracy of 92.2% (95% confidence interval = 88.4% to 94.8%).

CONCLUSIONS

Publications reporting algorithms for detecting breast cancer recurrence are limited in number and heterogeneous. A thorough analysis of the existing algorithms demonstrated the need for more standardization and validation. The meta-analysis reported a high accuracy overall, which indicates algorithms as promising tools to identify breast cancer recurrence at the population level. The rule-based approach combined with emerging machine learning algorithms could be interesting to explore in the future.

The Validity of Registered Synchronous Peritoneal Metastases from Colorectal Cancer in the Danish Medical Registries

Introduction

Treatment options for peritoneal metastases (PM) from colorectal cancer (CRC) have increased, their efficiency should be monitored. For this purpose, register-based data on PM can be used, if valid.

Purpose

We aimed to evaluate the completeness and positive predictive value (PPV) of synchronous peritoneal metastases (S-PM) registered among CRC patients in the Danish National Patient Register (DNPR) and/or the Danish National Pathology Register (the DNPatR) using the Danish Colorectal Cancer Group database (DCCG) as a reference.

Patients and Methods

We identified Danish patients with newly diagnosed primary CRC in the DCCG during 2014–2015. S-PM were routinely registered in the DCCG. We excluded patients with non-CRC cancers and identified S-PM using all three registries. We estimated the completeness and the PPV of registered S-PM in the DNPR, the DNPatR and the DNPR and/or the DNPatR (DNPR/DNPatR) in combination using the DCCG as the reference. We stratified by age, gender, WHO performance status, tumour location and distant metastases to liver and/or lungs.

Results

We identified 9142 patients with CRC in DCCG. In DCCG, 366 patients were registered with S-PM, among whom 213 in DCCG only, whereas 153 in DCCG and in at least one of DNPR and/or DNPatR. In DNPR/DNPatR, S-PM was registered with a completeness of 42% [95% CI: 37–47] and a PPV of 60% [95% CI: 54–66]. In the DNPR only, the completeness was 32% [95% CI: 27–37] and the PPV 57% [95% CI: 50–64]. The completeness in the DNPatR was 19% [95% CI: 15–23] and the PPV was 76% [95% CI: 68–85]. In the DNPR/DNPatR patients aged <60 years (57% [95% CI: 46–69]), patients with WHO performance status 0 (46% [95% CI: 37–54]) and patients with no distant metastases (58% [95% CI: 50–65]) were registered with a higher completeness.

Conclusion

Our algorithm demonstrates that the DNPR/DNPatR captures less than half of CRC patients with S-PM. Potential candidates for curative treatment options are registered with a higher completeness. Clinicians should be encouraged to register the presence of S-PM to increase the validity of register-based S-PM data.

Application of the Adaptive Validation Substudy Design to Colorectal Cancer Recurrence

Background

Among men and women diagnosed with colorectal cancer (CRC), 20-50% will develop a cancer recurrence. Cancer recurrences are not routinely captured by most population-based registries; however, linkage across Danish registries allows for the development of predictive models to detect recurrence. Successful application of such models in population-based settings requires validation against a gold standard to ensure the accuracy of recurrence identification.

Objective

We apply a recently developed validation study design for prospectively collected validation data to validate predicted CRC recurrences against gold standard diagnoses from medical records in an actively followed cohort of CRC patients in Denmark.

Methods

We use a Bayesian monitoring framework, traditionally used in clinical trials, to iteratively update classification parameters (positive and negative predictive values, and sensitivity and specificity) in an adaptive validation substudy design. This design allows determination of the sample size necessary to estimate the corresponding parameters and to identify when validation efforts can cease based on predefined criteria for parameter values and levels of precision.

Results

Among 355 men and women diagnosed with CRC in Denmark and actively followed semi-annually, there were 63 recurrences diagnosed by active follow-up and 70 recurrences identified by a predictive algorithm. The adaptive validation design met stopping criteria for the classification parameters after 120 patients had their recurrence information validated. This stopping point yielded parameter estimates for the classification parameters similar to those obtained when the entire cohort was validated, with 66% less patients needed for the validation study.

Conclusion

In this proof of concept application of the adaptive validation study design for outcome misclassification, we demonstrated the ability of the method to accurately determine when sufficient validation data have been collected. This method serves as a novel validation substudy design for prospectively collected data with simultaneous implementation of a validation study.

Healthcare utilisation in general practice and hospitals in the year preceding a diagnosis of cancer recurrence or second primary cancer: a population-based register study

Background

The organisation of cancer follow-up is under scrutiny in many countries, and general practice is suggested to become more involved. A central focus is timely detection of recurring previous cancer and new second primary cancer. More knowledge on the patient pathway before cancer recurrence and second primary cancer is warranted to ensure the best possible organisation of follow-up. We aimed to describe the healthcare utilisation in the year preceding a diagnosis of cancer recurrence or second primary cancer.

Methods

This nationwide register study comprises patients diagnosed with bladder, breast, colorectal, endometrial, lung, malignant melanoma and ovarian cancer in Denmark in 2008–2016. The frequency of healthcare contacts during the 12 months preceding a cancer recurrence or second primary cancer was estimated and compared to the frequency of cancer survivors in cancer remission. The main analyses were stratified on sex and healthcare setting. Furthermore, two sub-analyses were stratified on 1) sex, healthcare setting and age group and on 2) sex, healthcare setting and comorbidity status.

Results

The study population consisted of 7832 patients with recurrence and 2703 patients with second primary cancer. On average, the patients were in contact with general practice one time per month in the 12th month preceding a new cancer diagnosis (recurrence or second primary cancer). Increasing contact rates were seen from 7 months before diagnosis in general practice and from 12 months before diagnosis in hospitals. This pattern was more pronounced in patients with cancer recurrence, younger patients and patients with no comorbidity. For instance, the contact rate ratios for hospital contacts in non-comorbid women with recurrence demonstrated 30% more contacts in the 12th month before recurrence and 127% more contacts in the 2nd month before recurrence.

Conclusions

The results show that cancer survivors are already seen in general practice on a regular basis. The increasing contact rates before a diagnosis of cancer recurrence or second primary cancer indicate that a window of opportunity exists for more timely diagnosis; this is seen in both general practice and in hospitals. Thus, cancer survivors may benefit from improvements in the organisation of cancer follow-up.

Associations between blood cultures after surgery for colorectal cancer and long-term oncological outcomes

BACKGROUND

Systemic inflammation following curative surgery for colorectal cancer may be associated with increased risk of recurrence. [Correction added on 29 November 2019, after first online publication: text amended for accuracy.] This study investigated whether a clinically suspected infection, for which blood cultures were sent within 30 days after surgery for colorectal cancer, was associated with long-term oncological outcomes.

METHODS

This register-based national cohort study included all Danish residents undergoing surgery with curative intent for colorectal cancer between January 2003 and December 2013. Patients who developed recurrence or died within 180 days after surgery were not included. Associations between blood cultures taken within 30 days after primary surgery and overall survival, disease-free survival and recurrence-free survival were analysed using Cox regression models adjusted for relevant clinical confounders, including demographic data, cancer stage, co-morbidity, blood transfusion, postoperative complications and adjuvant chemotherapy.

RESULTS

The study included 21 349 patients, of whom 3390 (15·9 per cent) had blood cultures taken within 30 days after surgery. Median follow-up was 5·6 years. Patients who had blood cultures taken had an increased risk of all-cause mortality (hazard ratio (HR) 1·27, 95 per cent c.i. 1·20 to 1·35; P < 0·001), poorer disease-free survival (HR 1·22, 1·16 to 1·29; P < 0·001) and higher risk of recurrence (HR 1·15, 1·07 to 1·23; P < 0·001) than patients who did not have blood cultures taken.

CONCLUSION

A clinically suspected infection requiring blood cultures within 30 days of surgery for colorectal cancer was associated with poorer oncological outcomes.

Time from incident primary cancer until recurrence or second primary cancer: Risk factors and impact in general practice

OBJECTIVE

Specialised follow-up care after cancer treatment is changing towards increased involvement of general practice. To ensure timely detection of new cancer events, knowledge is warranted on the timing of cancer recurrence (CR) and second primary cancer (SPC), including risk factors for CR.

METHODS

This population-based register study included 67,092 patients diagnosed with malignant melanoma, bladder, lung, ovarian, endometrial, colorectal and breast cancer in Denmark in 2008-2016. The time from primary cancer to CR or SPC and risk factors for prolonged time to CR were analysed and stratified on sex and primary cancer type.

RESULTS

Cancer recurrence proportions ranged from 6% to 35%. The risk of CR increased profoundly within the first 3 years and then levelled off, except for breast cancer. A total of 3%-6% of patients had SPC, with monotonously increasing cumulative incidence proportions. Besides primary tumour characteristics, lower educational level, living alone and comorbidity were associated with earlier CR. For example, in female malignant melanoma, HRs and 95% confidence intervals were 0.47 (0.37-0.61) for high educational level, 1.40 (1.16-1.68) for living alone and 2.38 (1.53-3.70) for high comorbidity.

CONCLUSION

The results may inform stratified risk assessment in decision of frequency, location and duration of post-cancer follow-up care.

A validated algorithm for register-based identification of patients with recurrence of breast cancer-Based on Danish Breast Cancer Group (DBCG) data

BACKGROUND

Cancer recurrence is not routinely and completely registered in Danish national health registers, which challenges register-based research. The aim of this study was to develop and validate a register-based algorithm to identify patients with recurrence of breast cancer (BC).

METHODS

We conducted a cohort study based on data from Danish national health registers and used the Danish National Patient Register and the Danish National Pathology Register as sources to identify BC recurrence. We used data from the Danish Breast Cancer Group (DBCG) validated against medical records on recurrence status and recurrence date for 471 women with early stage unilateral BC as the gold standard of BC recurrence to assess the accuracy of the algorithm to identify BC recurrence.

RESULTS

The algorithm displayed a sensitivity of 97.3% (95% confidence interval (CI): 93.2-99.3), a specificity of 97.2% (95% CI: 94.8-98.7) and a positive predictive value of 94.4% (95% CI: 89.2-97.3). The concordance correlation coefficient for the agreement between recurrence dates generated by the algorithm and the gold standard was 0.97 (95% CI: 0.96-0.98), and the date was estimated within +/-30 days of the gold standard in 66% of the patients and within +/-60 days in 76% of the patients.

CONCLUSION

The developed algorithm almost perfectly identified BC recurrence and with reasonable timing compared to the gold standard.

Validity of Administrative Data in Identifying Cancer-related Events in Adolescents and Young Adults: A Population-based Study Using the IMPACT Cohort

BACKGROUND

Despite the importance of estimating population level cancer outcomes, most registries do not collect critical events such as relapse. Attempts to use health administrative data to identify these events have focused on older adults and have been mostly unsuccessful. We developed and tested administrative data-based algorithms in a population-based cohort of adolescents and young adults with cancer.

METHODS

We identified all Ontario adolescents and young adults 15-21 years old diagnosed with leukemia, lymphoma, sarcoma, or testicular cancer between 1992-2012. Chart abstraction determined the end of initial treatment (EOIT) date and subsequent cancer-related events (progression, relapse, second cancer). Linkage to population-based administrative databases identified fee and procedure codes indicating cancer treatment or palliative care. Algorithms determining EOIT based on a time interval free of treatment-associated codes, and new cancer-related events based on billing codes, were compared with chart-abstracted data.

RESULTS

The cohort comprised 1404 patients. Time periods free of treatment-associated codes did not validly identify EOIT dates; using subsequent codes to identify new cancer events was thus associated with low sensitivity (56.2%). However, using administrative data codes that occurred after the EOIT date based on chart abstraction, the first cancer-related event was identified with excellent validity (sensitivity, 87.0%; specificity, 93.3%; positive predictive value, 81.5%; negative predictive value, 95.5%).

CONCLUSIONS

Although administrative data alone did not validly identify cancer-related events, administrative data in combination with chart collected EOIT dates was associated with excellent validity. The collection of EOIT dates by cancer registries would significantly expand the potential of administrative data linkage to assess cancer outcomes.

A validated algorithm to identify recurrence of bladder cancer: a register-based study in Denmark

Purpose

Recurrence of cancer is not routinely registered in the national registers in Denmark. The aim of this study was to develop and validate a register-based algorithm to identify patients diagnosed with recurrence of invasive bladder cancer (BC).

Materials and methods

We performed a cohort study based on data from Danish national health registers. Diagnosis codes and procedural codes in the Danish National Patient Register and Systematized Nomenclature of Medicine codes in the Danish National Pathology Register were used as indicators of cancer recurrence. Status and date of recurrence as registered in the Danish Bladder Cancer Database (DaBlaCa-data) were used as the gold standard of BC recurrence to ascertain the accuracy of the algorithm.

Results

The algorithm reached a sensitivity of 85% (95% CI: 78–91), a specificity of 90% (95% CI: 79–96), and a positive predictive value of 95% (95% CI: 89–98). The algorithm demonstrated superior performance in patients undergoing cystectomy compared to patients undergoing radiotherapy as primary BC treatment. The concordance correlation coefficient for the agreement between the recurrence dates generated by the algorithm and the gold standard was 0.96 (95% CI: 0.95–0.98), and the estimated date was set within 90 days of the gold standard date for 90% of patients.

Conclusion

The proposed algorithm to identify patients diagnosed with BC recurrence from Danish national registries showed excellent performance in terms of ascertaining occurrence and the timing of BC recurrence.

Long-Term Outcomes of Robot-Assisted Surgery in Patients with Colorectal Cancer

BACKGROUND

Robotic technology has been proven to be a safe alternative to conventional laparoscopy with regards to the peri- and postoperative clinical outcomes. Oncological outcomes have been scarcely examined. The purpose of this study was to examine the disease-free survival in relation to the two surgical approaches: robot-assisted surgery and conventional laparoscopy. In addition, all-cause mortality and recurrence-free survival were investigated.

METHODS

Between January 2010 and December 2015, patients, undergoing either laparoscopic or robot-assisted elective, curative-intended surgery for colorectal cancer were included.

RESULTS

A total of 9184 patients underwent surgery in the study period: 5978 patients for colon cancer and 3206 patients for rectal cancer. Among patients with colon cancer, 331 patients (5.5%) underwent robot-assisted surgery, and 449 patients (14.0%) underwent robot-assisted surgery in the rectal cancer group. In the adjusted analyses, the hazard ratio (HR) for disease-free survival, for patients with colon cancer was 0.91 [95% confidence interval (CI) 0.71-1.18]. For patients with rectal cancer, the adjusted HR was 0.83 (95% CI 0.65-1.06). No difference in all-cause mortality and recurrence-free survival were observed.

CONCLUSIONS

The study demonstrated comparable rates of disease-free survival, all-cause mortality, and recurrence-free survival when comparing robot-assisted surgery with conventional laparoscopy in patients with colorectal cancer.

Validating an algorithm to identify metastatic gastric cancer in the absence of routinely collected TNM staging data

Background

Accurate TNM stage information is essential for cancer health services research, but is often impractical and expensive to collect at the population-level. We evaluated algorithms using administrative healthcare data to identify patients with metastatic gastric cancer.

Methods

A population-based cohort of gastric cancer patients diagnosed between 2005 and 2007 identified from the Ontario Cancer Registry were linked to routinely collected healthcare data. Reference standard data identifying metastatic disease were obtained from a province-wide chart review, according to the Collaborative Staging method. Algorithms to identify metastatic gastric cancer were created using administrative healthcare data from hospitalization, emergency department, and physician billing records. Time frames of data collection in the peri-diagnosis period, and the diagnosis codes used to identify metastatic disease were varied. Algorithm sensitivity, specificity, and accuracy were evaluated.

Results

Of 2366 gastric cancer patients, included within the chart review, 54.3% had metastatic disease. Algorithm sensitivity ranged from 50.0- 90%, specificity ranged from 27.6 - 92.5%, and accuracy from 61.5 - 73.4%. Sensitivity and specificity were maximized when the most conservative list of diagnosis codes from hospitalization and outpatient records in the six months prior to and the six months following diagnosis were included.

Conclusion

Algorithms identifying metastatic gastric cancer can be used for research purposes using administrative healthcare data, although they are imperfect measures. The properties of these algorithms may be generalizable to other high fatality cancers and other healthcare systems. This study provides further support for the collection of population-based, TNM stage data.

Electronic supplementary material

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Breast cancer recurrence, bone metastases, and visceral metastases in women with stage II and III breast cancer in Denmark

PURPOSE

We developed and validated algorithms to identify metastases and breast cancer recurrence in Danish medical registries. We computed the incidence rate (IR) and hazard ratios (HRs) to evaluate predictors of these outcomes in stage II/III breast cancer patients.

METHODS

We included all women in Denmark diagnosed during 1999-2011 with regional or stage II/III breast cancer. Demographic, tumor, and treatment data were ascertained from population-based health registries. To facilitate diagnostic work-up of the primary cancer, follow-up began 180 days after diagnosis and continued until recurrence/metastases, death, or 31 December 2012, whichever occurred first. We computed the positive predictive values (PPVs) of recurrence, bone metastases, and visceral metastases using medical records as a gold standard. We calculated the cumulative incidence, IR per 10,000 person years, and used Cox regression to compute the HRs and associated 95% confidence intervals (95% CI) for each outcome.

RESULTS

Among 23,478 patients, 7073 had regional stage and 16,405 had stage II/III breast cancer. The PPV for recurrence was 72.6% (95% CI 59.3, 83.3%). The PPVs for bone and visceral metastases were 92.3% (95% CI 69.3-99.2%) and 70.8% (95% CI 51.1, 85.9%), but had low sensitivity. Five-year cumulative incidence of recurrence, bone metastases, and visceral metastases were 18.4, 2.2, and 5.2%, with corresponding 5-year IRs of 540 (95% CI 524, 557), 60 (95% CI 55, 65), and 144 (95% CI 136, 152), respectively. Predictors of recurrence and metastases included age, stage, hormone receptor status, and cancer treatment.

CONCLUSION

Our algorithms show moderate to high PPVs for recurrence and metastases. The IRs of metastases were lower compared with other registry-based cohort studies, so may be underestimated in Danish registries.

Associations of Statin Use With Colorectal Cancer Recurrence and Mortality in a Danish Cohort

In earlier studies of the influence of hydroxymethylglutaryl-coenzyme A reductase inhibitors (also known as statins) on colorectal cancer prognosis, investigators reported a reduced rate of cancer-specific mortality. Studies of recurrence are few and small. Using data from Danish registries, we followed 21,152 patients diagnosed with stage I-III colorectal cancer from 2001 to 2011. We estimated the association between statin use in the preceding year and cancer recurrence, cancer-specific mortality, and all-cause mortality rates. We identified 5,036 recurrences, 7,084 deaths from any cause, and 4,066 deaths from colorectal cancer. After adjustment for potential confounders, statin use was not associated with recurrence (adjusted hazard ratio (aHR) = 1.01, 95% confidence interval (CI): 0.93, 1.09), but it was associated with death from colorectal cancer (aHR = 0.72, 95% CI: 0.65, 0.79) and death from any cause (aHR = 0.72, 95% CI: 0.67, 0.76). Statin use in the year preceding recurrence was associated with a reduced risk of cancer-specific mortality (aHR = 0.83, 95% CI: 0.74, 0.92) but also a reduced risk of death from any other cause (aHR = 0.78, 95% CI: 0.61, 1.00). Statin use was not associated with a reduced rate of colorectal cancer recurrence, but it was associated with a reduced rate of cancer-specific mortality, which suggests that there is no cancer-directed benefit; therefore, there is no basis to prescribe statins to colorectal cancer patients who do not have cardiovascular indications.

Descriptive characteristics of colon and rectal cancer recurrence in a Danish population-based study

BACKGROUND

Recurrence is a common outcome among patients that have undergone an intended curative resection for colorectal cancer. However, data on factors that influence colorectal cancer recurrence are sparse. We report descriptive characteristics of both colon and rectal cancer recurrence in an unselected population.

MATERIAL AND METHODS

We identified 21,152 patients with colorectal cancer diagnosed between May 2001 and December 2011 and registered with the Danish Colorectal Cancer Group. Recurrences were identified in 3198 colon and 1838 rectal cancer patients during follow-up. We calculated the frequency, proportion, and incidence rates of colon and rectal cancer recurrence within descriptive categories, and the cumulative five- and ten-year incidences of recurrence, treating death as a competing risk. We used a Cox proportional hazard model to calculate hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

Recurrence risk was highest in the first three years of follow-up. Patients <55 years old at initial diagnosis (incidence rate for colon: 7.2 per 100 person-years; 95% CI: 6.5-7.9; rectum: 8.1 per 100 person-years; 95% CI: 7.2-9.0) and patients diagnosed with stage III cancer (colon HR: 5.70; 95% CI: 4.61-7.06; rectal HR: 7.02; 95% CI: 5.58-8.82) had increased risk of recurrence. Patients diagnosed with stage III cancer from 2009 to 2011 had a lower incidence of recurrence than those diagnosed with stage III cancer in the years before. Cumulative incidences of colon and rectal cancer recurrence were similar for both cancer types among each descriptive category.

CONCLUSIONS

In this population, increases in colorectal cancer recurrence risk were associated with younger age and increasing stage at diagnosis. Cumulative incidence of recurrence did not differ by cancer type. Descriptive characteristics of colon and rectal cancer recurrence may help to inform patient-physician decision-making, and could be used to determine adjuvant therapies or tailor surveillance strategies so that recurrence may be identified early, particularly within the first 3 years of follow-up.

Challenges in translating endpoints from trials to observational cohort studies in oncology

Clinical trials are considered the gold standard for examining drug efficacy and for approval of new drugs. Medical databases and population surveillance registries are valuable resources for post-approval observational research, which are increasingly used in studies of benefits and risk of new cancer drugs. Here, we address the challenges in translating endpoints from oncology trials to observational studies. Registry-based cohort studies can investigate real-world safety issues – including previously unrecognized concerns – by examining rare endpoints or multiple endpoints at once. In contrast to clinical trials, observational cohort studies typically do not exclude real-world patients from clinical practice, such as old and frail patients with comorbidity. The observational cohort study complements the clinical trial by examining the effectiveness of interventions applied in clinical practice and by providing evidence on long-term clinical outcomes, which are often not feasible to study in a clinical trial. Various endpoints can be included in clinical trials, such as hard endpoints, soft endpoints, surrogate endpoints, and patient-reported endpoints. Each endpoint has it strengths and limitations for use in research studies. Endpoints used in oncology trials are often not applicable in observational cohort studies which are limited by the setting of standard clinical practice and by non-standardized endpoint determination. Observational studies can be more helpful moving research forward if they restrict focus to appropriate and valid endpoints.

Enhancing Breast Cancer Recurrence Algorithms Through Selective Use of Medical Record Data

BACKGROUND

The utility of data-based algorithms in research has been questioned because of errors in identification of cancer recurrences. We adapted previously published breast cancer recurrence algorithms, selectively using medical record (MR) data to improve classification.

METHODS

We evaluated second breast cancer event (SBCE) and recurrence-specific algorithms previously published by Chubak and colleagues in 1535 women from the Life After Cancer Epidemiology (LACE) and 225 women from the Women's Health Initiative cohorts and compared classification statistics to published values. We also sought to improve classification with minimal MR examination. We selected pairs of algorithms-one with high sensitivity/high positive predictive value (PPV) and another with high specificity/high PPV-using MR information to resolve discrepancies between algorithms, properly classifying events based on review; we called this "triangulation." Finally, in LACE, we compared associations between breast cancer survival risk factors and recurrence using MR data, single Chubak algorithms, and triangulation.

RESULTS

The SBCE algorithms performed well in identifying SBCE and recurrences. Recurrence-specific algorithms performed more poorly than published except for the high-specificity/high-PPV algorithm, which performed well. The triangulation method (sensitivity = 81.3%, specificity = 99.7%, PPV = 98.1%, NPV = 96.5%) improved recurrence classification over two single algorithms (sensitivity = 57.1%, specificity = 95.5%, PPV = 71.3%, NPV = 91.9%; and sensitivity = 74.6%, specificity = 97.3%, PPV = 84.7%, NPV = 95.1%), with 10.6% MR review. Triangulation performed well in survival risk factor analyses vs analyses using MR-identified recurrences.

CONCLUSIONS

Use of multiple recurrence algorithms in administrative data, in combination with selective examination of MR data, may improve recurrence data quality and reduce research costs.