Less pitfalls and variation in population based cancer survival comparisons within the European Union: Lessons from colorectal cancer patients in neighbouring regions in Denmark and Germany - The Fehmarn Belt project

Colorectal Cancer Survival in German-Danish Border Regions-A Registry-Based Cohort Study

The aim of this study was (i) to update the reporting of colorectal cancer survival differences over time in the German-Danish border region (Schleswig-Holstein, Southern Denmark, and Zealand) and (ii) to assess the extent to which it can be explained by stage and primary treatment. Incident invasive colorectal cancer cases diagnosed from 2004 to 2016 with a follow-up of vital status through 31 December 2017 were extracted from cancer registries. Analyses were conducted by anatomical subsite and for four consecutive periods. Kaplan-Meier curves and log-rank tests were computed. Cox regression models using data from Schleswig-Holstein from 2004 to 2007 as the reference category were run while controlling for age, sex, stage, and treatment. The cox regression models showed decreasing hazard ratios of death for all three regions over time for both anatomical subsites. The improvement was stronger in the Danish regions, and adjustment for age, sex, stage, and treatment attenuated the results only slightly. In 2014-2016, colon cancer survival was similar across regions, while rectal cancer survival was significantly superior in the Danish regions. Regional survival differences can only partially be explained by differing stage distribution and treatment and may be linked additionally to healthcare system reforms and screening efforts.

Survival of breast cancer patients in German-Danish border regions - A registry-based cohort study

BACKGROUND AND AIM

Denmark reports slightly lower breast cancer survival before 2010 than its neighbouring country Germany. Previous research is limited by lacking stage and treatment information. This study aims to investigate differences in breast cancer survival between the bordering regions Schleswig-Holstein (Germany), Southern Denmark and Zealand (Denmark) using registry data including stage and treatment information.

METHOD

Invasive female breast cancer cases diagnosed during 2004-2013 with follow up through 31st December 2014 were extracted from cancer registries. Cases notified by death certificates only and those aged 90+ years were excluded. Kaplan-Meier curves and log-rank tests were computed. Cox regression analysis was conducted with adjustment for year of diagnosis, age, stage, and treatment.

RESULTS

The analytical sample included 42,966 cases. Kaplan-Meier curves and log-rank tests show significant survival differences between the regions. The Cox regression model adjusted for year of diagnosis and age shows significantly worse overall survival of breast cancer patients in both Danish regions compared to Schleswig-Holstein with hazard ratios (HR) of 1.09 (95 % CI: 1.04; 1.15) for patients from Southern Denmark (SD) and 1.25 (95 % CI: 1.18; 1.32) for residents of Zealand (ZL). This effect diminished after adjustment for stage and treatment (HR: 1.05 (SD), 1.09 (ZL) 95 % CI: 0.99; 1.10 (SD), 1.03; 1.15 (ZL)).

CONCLUSION

Survival differences can be explained by differing stage distribution and treatment administration, which formerly were more favourable in Schleswig-Holstein. The survival gap will probably close due to Denmark's national screening program and increased use of adjuvant cancer therapy.

Essential TNM: a registry tool to reduce gaps in cancer staging information

Accurate information on the extent of disease around the time of diagnosis is an important component of cancer care, in defining disease prognosis, and evaluating national and international cancer control policies. However, the collection of stage data by population-based cancer registries remains a challenge in both high-income and low and middle-income countries. We emphasise the lack of availability and comparability of staging information in many population-based cancer registries and propose Essential TNM, a simplified staging system for cancer registries when information on full Tumour, Node, Metastasis (TNM) is absent. Essential TNM aims at staging cancer in its most advanced disease form by summarising the extent of disease in the order of distant metastasis (M), regional lymph node involvement (N), and tumour size or extension, or both (T). Flowcharts and rules have been developed for coding these elements in breast, cervix, prostate, and colon cancers, and combining them into stage groups (I-IV) that correspond to those obtained by full TNM staging. Essential TNM is comparable to the Union for International Cancer Control TNM stage groups and is an alternative to providing staging information by the population-based cancer registries that complies with the objectives of the Global Initiative for Cancer Registry Development.

Adjuvant chemotherapy and relative survival of patients with stage II colon cancer - A EURECCA international comparison between the Netherlands, Denmark, Sweden, England, Ireland, Belgium, and Lithuania

BACKGROUND

The aim of the present EURECCA international comparison is to compare adjuvant chemotherapy and relative survival of patients with stage II colon cancer between European countries.

METHODS

Population-based national cohort data (2004-2009) from the Netherlands (NL), Denmark (DK), Sweden (SE), England (ENG), Ireland (IE), and Belgium (BE) were obtained, as well as single-centre data from Lithuania. All surgically treated patients with stage II colon cancer were included. The proportion of patients receiving adjuvant chemotherapy was calculated and compared between countries. Besides, relative survival was calculated and compared between countries.

RESULTS

Overall, 59,154 patients were included. The proportion of patients receiving adjuvant chemotherapy ranged from 7.1% to 29.0% (p < 0.001). Compared with NL, a better adjusted relative survival was observed in SE (stage II: relative excess risks (RER) 0.53, 95% confidence interval (CI) 0.44-0.64; p < 0.001), and BE (stage II: RER 0.84, 95% CI 0.76-0.92; p < 0.001), and in IE for patients with stage IIA disease (RER 0.80, 95% CI 0.65-0.98; p = 0.03).

CONCLUSION

The proportion of patients with stage II colon cancer receiving adjuvant chemotherapy varied largely between seven European countries. No clear linear pattern between adjuvant chemotherapy and adjusted relative survival was observed. Compared with NL, SE and BE showed an improved adjusted relative survival for stage II disease, and IE for patients with stage IIA disease only. Further research into selection criteria for adjuvant chemotherapy could eventually lead to individually tailored, optimal treatment of patients with stage II colon cancer.