BackgroundRecent studies suggest that cancer increases risk of atrial fibrillation. Whether atrial fibrillation is a marker for underlying occult cancer is unknown.MethodsWe conducted a cohort study (1980–2011) of all Danish patients with new-onset atrial fibrillation. To examine cancer risk, we computed absolute risk at 3 months and standardized incidence ratios (SIRs) by comparing observed cancer incidence among patients newly diagnosed with atrial fibrillation with that expected based on national cancer incidence during the period.ResultsMedian follow-up time was 3.4 years among 269 742 atrial fibrillation patients. Within 3 months of follow-up, 6656 cancers occurred (absolute risk, 2.5%; 95% confidence intervals [CI], 2.4%–2.5%) versus 1302 expected, yielding a SIR of 5.11; 95% CI, 4.99–5.24. Associations were particularly strong for cancers of the lung, kidney, colon, ovary, and for non-Hodgkin's lymphoma. The SIR within 3 months of follow-up was 7.02; 95% CI, 6.76–7.28 for metastatic and 3.53; 95% CI, 3.38–3.68 for localized cancer. Beyond 3 months of follow-up, overall cancer risk was modestly increased (SIR, 1.13; 95% CI, 1.12–1.15).ConclusionPatients with new-onset atrial fibrillation had a markedly increased relative risk of a cancer diagnosis within the next three months, however, corresponding absolute risk was small.

Colorectal cancer recurrences are difficult to ascertain accurately and efficiently. We developed and validated an algorithm to identify recurrences that uses Danish medical registries. The algorithm uses metastasis and chemotherapy codes in the Danish National Patient Registry and codes indicating cancer recurrence in the Danish Pathology Registry. We applied the algorithm to a cohort (n 5 21,246) of colorectal cancer patients diagnosed 2001-2011 and followed through 2012. In a cohort (n 5 355) of two groups of actively followed patients, we compared the imputed recurrence data with recurrences diagnosed by regular follow-up. We compared cumulative incidence curves of imputed recurrence in local and regional stage patients from the large cohort, and of imputed and diagnosed recurrences in the actively followed cohort. In the 355 members of the actively followed cohort, our algorithm correctly identified 60 of 63 recurrences [sensitivity 5 95%; 95% confidence interval (CI) 87-99%] and misclassified only 10 of 292 without recurrence (specificity 5 97%; 95% CI 94-98%). Cumulative incidence curves showed that members of the large cohort with regional disease had much higher incidence of imputed recurrence than those with local disease. In the actively followed cohort, the cumulative incidence of recurrence overlapped substantially when recurrence was imputed by our algorithm or using the follow-up data. Despite some limitations regarding ambiguous pathology codes, our algorithm showed excellent performance against actively followed recurrence data, and the expected relation between recurrence risk and cancer stage. It can be used in the Danish registries and adapted to similar registries elsewhere.

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.

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.

ObjectiveTo explore the completeness of tumor, node, metastasis (TNM) staging for colon and rectal cancer in the Danish Cancer Registry.Material and methodsFrom the Danish Cancer Registry, we retrieved data on TNM stage, year of diagnosis, sex, and age for 15,976 and 8292 patients, respectively, with first diagnoses of colon or rectal cancer during the 2004–2009 period. From the Danish National Patient Register, we retrieved data on comorbidity (computed as Charlson Comorbidity Index scores). We calculated the completeness of TNM staging overall, by each stage component, and according to a stage algorithm allowing some missing stage components. Analyses were stratified by sex, age, year of diagnosis, and Charlson Comorbidity Index score.ResultsFor colon and rectal cancer, overall TNM completeness was 67.8% (95% confidence interval [CI]: 67.0%–68.5%) and 68.1% (95% CI: 67.0%–69.1%), respectively. For both cancers, completeness decreased with increasing age and level of comorbidity, whereas differences between the sexes were minor. Over the study period, TNM completeness for colon cancer decreased from 71.3% (95% CI: 69.5%–73.0%) to 64.8% (95% CI: 63.0%–66.6%), whereas the completeness for rectal cancer remained stable over time. When using the stage algorithm, the completeness rose markedly, to 81.1% for colon cancer and 79.0% for rectal cancer.ConclusionOne-third of colon and rectal cancer cases in the Danish Cancer Registry had missing TNM stage information, which varied with age and level of comorbidity. Cancer cases with unknown staging warrant serious consideration of the methodological implications in future epidemiological studies monitoring cancer incidence and outcomes.

ObjectiveTo evaluate recent trends in the prevalence and impact of comorbidity on colorectal cancer (CRC) survival in the Central Region of Denmark.Material and methodsUsing the Danish National Registry of Patients, we identified 5,777 and 2,964 patients with a primary colon or rectal cancer, respectively, from 2000 through 2011. We estimated survival according to Charlson Comorbidity Index scores and computed mortality rate ratios (MRRs) using Cox proportional hazard regression analysis, adjusting for age and sex.ResultsMore than one-third of CRC patients had comorbidity at diagnosis. During the study period, 1-year survival increased substantially in colon cancer patients with Charlson score 0 (72% to 80%) and modestly for Charlson score 3+ patients (43% to 46%). Using colon cancer patients with Charlson score 0 as reference, adjusted 1-year MRRs in patients with Charlson score 3+ were 2.19 (95% confidence interval [CI]: 1.57–3.05) in 2000–2002 and 2.56 (95% CI: 1.96–3.35) in 2009–2011. One-year survival after rectal cancer improved from 81% to 87% in patients with Charlson score 0 and from 56% to 60% in Charlson score 3+. Corresponding MRRs in patients with Charlson 3+ were 2.21 (95% CI: 1.33–3.68) in 2000–2002 and 3.09 (95% CI: 1.91–5.00) in 2009–2011 using Charlson score 0 as reference. Five-year MRRs did not differ substantially from 1-year MRRs.ConclusionComorbidity was common among CRC patients and was associated with poorer prognosis. We observed improved survival from 2000 to 2011 for all comorbidity levels, with least improvement for colon cancer patients with comorbid conditions.

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SUMMARY BackgroundSystemic glucocorticoids are potent immunosuppressants, potentially facilitating carcinogenesis. Studies examining glucocorticoids and colorectal cancer risk are few.