The Danish National Lymphoma Registry: Coverage and Data Quality.

BACKGROUND: The Danish National Lymphoma Register (LYFO) prospectively includes information on all lymphoma patients newly diagnosed at hematology departments in Denmark. The validity of the clinical information in the LYFO has never been systematically assessed. AIM: To test the coverage and data quality of the LYFO. METHODS: The coverage was tested by merging data of the LYFO with the Danish Cancer Register and the Danish National Patient Register, respectively. The validity of the LYFO was assessed by crosschecking with information from medical records in subgroups of patients. A random sample of 3% (N = 364) was made from all patients in the LYFO. In addition, four subtypes of lymphomas were validated: CNS lymphomas, diffuse large B-cell lymphomas, peripheral T-cell lymphomas, and Hodgkin lymphomas. A total of 1,706 patients from the period 2000-2012 were included. The positive predictive values (PPVs) and completeness of selected variables were calculated for each subgroup and for the entire cohort of patients. RESULTS: The comparison of data from the LYFO with the Danish Cancer Register and the Danish National Patient Register revealed a high coverage. In addition, the data quality was good with high PPVs (87% to 100%), and high completeness (92% to 100%). CONCLUSION: The LYFO is a unique, nationwide clinical database characterized by high validity, good coverage and prospective data entry. It represents a valuable resource for future lymphoma research.

Hypermethylation of DAPK1 is an independent prognostic factor predicting survival in diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma. Improvements in overall survival have been observed with the introduction of rituximab in combination with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), however, prognostic markers are still needed. Methylation of the death associated protein kinase (DAPK or DAPK1) gene and TP53 mutations are likely to have prognostic value in DLBCL. We have assessed TP53 mutations and allelic DAPK1 methylation patterns in a cohort of 119 DLBCL patients uniformly treated with R-CHOP-like regimens. We found that DAPK1 promoter methylation was associated with shorter overall survival (p=0.017) and disease-specific survival (p=0.023). In multivariate analyses DAPK1 methylation remained as an independent prognostic factor predicting disease-specific survival (p=0.038). When only considering individuals heterozygous for the rs13300553 SNP monoallelic methylation of the A-allele was associated with shorter overall- and disease-specific survival (p<0.001). Patients carrying both DAPK1 methylation and a TP53 mutation had an inferior survival compared to patients carrying only one of these molecular alterations, however, this was borderline statistically significant. Allele-specific DAPK1 methylation patterns were also studied in a cohort of 67 multiple myeloma patients, and all of the methylated multiple myeloma samples heterozygous for the rs13300553 SNP were methylated on both alleles.