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Saarbrücken, Germany

Holleczek B.,Saarland Cancer Registry | Brenner H.,German Cancer Research Center
European Journal of Cancer

Background: Survival studies using data from population-based cancer registries allow assessing effectiveness of cancer care on a population level. However, population-based cancer registries differ in the proportion of cases first notified by death certificate, as well as in the efforts to trace back such death certificate notifications (DCN). We aimed to assess the impact of such trace back on population-based cancer survival estimates. Materials and methods: In this study from the population-based Saarland Cancer Registry (Germany) we investigated the survival experience of successfully traced back DCN cases from 1994 to 2003. Five-year relative survival of patients with DCN cancers and the effect of trace back on population-based 5-year relative survival estimates were analysed by age and tumour site. Results: Twelve percent of all cancers were DCN and such cases occurred most often amongst sites with poor prognosis and amongst elderly patients. Approximately half of DCN cases could be successfully traced back. Five-year relative survival of patients with DCN cancers with trace back was 2%. The inclusion of DCN cancers with additional registrations reduced the 5-year relative survival estimate for all cancers combined by 4% points. Reductions were stronger for older patients and highly fatal cancers. Conclusions: Trace back results in increased inclusion of patients with very poor prognosis. Varying extent of trace back across registries may compromise comparability of cancer survival estimates and should be taken into account in comparative cancer survival studies. © 2011 Elsevier Ltd. All rights reserved. Source

Brenner H.,German Cancer Research Center | Holleczek B.,Saarland Cancer Registry
Cancer Epidemiology Biomarkers and Prevention

Background: Studies of cancer survival by population-based cancer registries are a key component in monitoring progress against cancer. Patients notified by death certificates only (DCO) are commonly excluded from such studies. The validity of this "exclude DCO"approach has been questioned and an alternative "correct for DCO" approach has been proposed. Methods: We assess the validity of both the "exclude DCO" approach and the "correct for DCO" approach using model calculations. We illustrate implications for population-based cancer survival analyses by analyses of 5-year relative survival of cancer patients in Saarland, Germany. Results: The "exclude DCO" approach provides (too) optimistic survival estimates and the "correct for DCO"approach provides (too) pessimistic survival estimates under plausible assumptions. For example, in case of true survival of 50%, underascertainment of 5% of surviving patients and of 15% of dying patients (yielding a proportion of DCO cases of 7.7%), the two approaches would provide survival rate estimates of 52.8% and 48.8%, respectively. The difference of survival estimates obtained with both approaches increases with incompleteness of registration and the proportion of DCO cases. Trace back of DCO cases shifts survival estimates from the former toward the latter estimate. Conclusions: In case of nonnegligible DCO proportions, cancer survival studies should not be exclusively based on either the "exclude DCO" or the "correct for DCO" approach. A combination of estimates from both approaches may be useful to delineate a plausibility range for true survival. Impact: Our results may help to enhance validity and comparability of population-based cancer survival estimates. ©2011 AACR. Source

Holleczek B.,Saarland Cancer Registry | Brenner H.,German Cancer Research Center
Computer Methods and Programs in Biomedicine

Period analysis is increasingly employed in analyses of long-term survival of patients with chronic diseases such as cancer, as it derives more up-to-date survival estimates than traditional cohort based approaches. It has recently been extended with regression modelling using generalized linear models, which increases the precision of the survival estimates and enables to assess and account for effects of additional covariates.This paper provides a detailed presentation how model based period analysis may be used to derive population-based absolute and relative survival estimates using the freely available R language and statistical environment and already available R programs for period analysis.After an introduction of the underlying regression model and a description of the software tools we provide a step-by-step implementation of two regression models in R and illustrate how estimates and a test for trend over time in relative survival may be derived using data from a population based cancer registry. © 2012 Elsevier Ireland Ltd. Source

Ordonez-Mena J.M.,German Cancer Research Center | Schottker B.,German Cancer Research Center | Haug U.,German Cancer Research Center | Muller H.,German Cancer Research Center | And 4 more authors.
Cancer Epidemiology Biomarkers and Prevention

Background: Several observational studies assessed the relationship between serum 25-hydroxyvitamin D [25(OH)D] concentrations and the risk of cancer but results were inconclusive. Methods: We measured 25(OH)D concentrations in a population-based cohort study of 9,949 men and women ages 50 to 74 years in Saarland, Germany. Comprehensively adjusted Cox regression models were applied to estimate HRs and 95% confidence intervals (CI) for the association between season-standardized 25 (OH)D concentrations and total and site-specific cancer incidence. Results: Overall, during a median of 8 years of follow-up, 873 subjects developed cancer; the most common being prostate (171), breast (137), lung (136), and colorectal (136) cancer. Low season-standardized 25(OH)D (>30, 35, 40, or 36 nmol/L in winter, spring, summer, and autumn, respectively) was neither significantly associated with total cancer incidence (HR, 1.10; 95% CI, 0.93-1.30) nor with site-specific cancer incidence. However, a significantly increased overall cancer risk was observed for low 25(OH)D among men, nonobese subjects and subjects reporting low fish consumption and for high 25(OH)D in nonsmokers and nonobese subjects. Accordingly, restricted cubic splines to investigate dose-response relationships curves showed an inverse association of 25(OH)D levels and total cancer risk in men but not in women. Conclusions: 25(OH)D concentrations were significantly associated with overall cancer incidence in subgroups of this large cohort from Germany. No significant association was observed with site-specific cancers but this could be due to a limited statistical power for these endpoints. Impact: Further research should clarify whether and to what extent specific risk groups might profit from vitamin D supplementation. Cancer Epidemiol Biomarkers Prev; 22(5); 905-16 © 2013 AACR. Source

Schottker B.,German Cancer Research Center | Haug U.,German Cancer Research Center | Schomburg L.,Charite - Medical University of Berlin | Kohrle J.,Charite - Medical University of Berlin | And 4 more authors.
American Journal of Clinical Nutrition

Background: Serum 25-hydroxyvitamin D [25(OH)D] concentration has been linked to mortality in several studies, but appropriate cutoffs to define risk categories are under debate. Objective: We aimed to conduct a repeated-measurements analysis on the association of serum 25(OH)D concentrations with all-cause and cause-specific mortality, with particular attention given to the shape of dose-response relations. Design: Concentrations of 25(OH)D were measured in n = 9578 baseline and n = 5469 5-y follow-up participants of the ESTHER study, which is a German population-based cohort aged 50-74 y at baseline. Deaths were recorded during 9.5 y of follow-up (median). Restricted cubic splines were used to assess dose-response relations, and Cox regression with time-dependent variables was used to estimate hazard ratios. Results: During follow-up, 1083 study participants died; of those, 350 individuals died of cardiovascular diseases, 433 individuals died of cancer, and 55 individuals died of respiratory diseases. The overall mortality [HR (95% CI)] of subjects with vitamin D deficiency [25(OH)D concentrations <30 nmol/L] or vitamin D insufficiency [25(OH)D concentrations from 30 to 50 nmol/L) was significantly increased [1.71 (1.43, 2.03) and 1.17 (1.02, 1.35), respectively] compared with that of subjects with sufficient 25(OH)D concentrations (>50 nmol/L)]. Vitamin D deficiency was also associated with increased cardiovascular mortality [1.39 (95% CI: 1.02, 1.89)], cancer mortality [1.42 (95% CI: 1.08, 1.88)] and respiratory disease mortality [2.50 (95% CI: 1.12, 5.56)]. The association of 25(OH)D concentrations with all-cause mortality proved to be a nonlinear inverse association with risk that started to increase at 25(OH)D concentrations <75 nmol/L. Conclusions: In this large cohort study, serum 25(OH)D concentrations were inversely associated with all-cause and cause-specific mortality. In particular, vitamin D deficiency [25(OH)D concentration <30 nmol/L] was strongly associated with mortality from all causes, cardiovascular diseases, cancer, and respiratory diseases. Copyright © 2013 American Society for Nutrition. Source

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