<abstract xmlns="http://www.w3.org/1999/xhtml"><sec id="j_sjph-2016-0012_s_391_w2aab3b8c14b1b7b1aab1c15b1Aa"><h3>Background</h3><p>Cancer patients’ survival is an extremely important but complex indicator for assessing regional or global inequalities in diagnosis practices and clinical management of cancer patients. The population-based cancer survival comparisons are available through international projects (i.e. CONCORD, EUROCARE, OECD Health Reports) and online systems (SEER, NORDCAN, SLORA). In our research we aimed to show that noticeable differences in cancer patients’ survival may not always reflect the real inequalities in cancer care, but can also appear due to variations in the applied methodology for relative survival calculation.</p></sec><sec id="j_sjph-2016-0012_s_392_w2aab3b8c14b1b7b1aab1c15b2Aa"><h3>Methods</h3><p>Four different approaches for relative survival calculation (cohort, complete, period and hybrid) have been implemented on the data set of Slovenian breast cancer patients diagnosed between 2000 and 2009, and the differences in survival estimates have been quantified. The major cancer survival comparison studies have been reviewed according to the selected relative survival calculation approach.</p></sec><sec id="j_sjph-2016-0012_s_394_w2aab3b8c14b1b7b1aab1c15b3Aa"><h3>Results</h3><p>The gap between four survival curves widens with time; after ten years of follow up the difference increases to more than 10 percent points between the highest (hybrid) and the lowest (cohort) estimates. In population-based comparison studies, the choice of the calculation approach is not uniformed; we noticed a tendency of simply using the approach which yields numerically better survival estimates.</p></sec><sec id="j_sjph-2016-0012_s_395_w2aab3b8c14b1b7b1aab1c15b4Aa"><h3>Conclusion</h3><p>The population-based cancer relative survival, which is continually reported by recognised research groups, could not be compared directly as the methodology is different, and, consequently, final country scores differ. A uniform survival measure would be of great benefit in the cancer care surveillance.</p></sec></abstract>

BackgroundCancer patients’ survival is an extremely important but complex indicator for assessing regional or global inequalities in diagnosis practices and clinical management of cancer patients. The population-based cancer survival comparisons are available through international projects (i.e. CONCORD, EUROCARE, OECD Health Reports) and online systems (SEER, NORDCAN, SLORA). In our research we aimed to show that noticeable differences in cancer patients’ survival may not always reflect the real inequalities in cancer care, but can also appear due to variations in the applied methodology for relative survival calculation.MethodsFour different approaches for relative survival calculation (cohort, complete, period and hybrid) have been implemented on the data set of Slovenian breast cancer patients diagnosed between 2000 and 2009, and the differences in survival estimates have been quantified. The major cancer survival comparison studies have been reviewed according to the selected relative survival calculation approach.ResultsThe gap between four survival curves widens with time; after ten years of follow up the difference increases to more than 10 percent points between the highest (hybrid) and the lowest (cohort) estimates. In population-based comparison studies, the choice of the calculation approach is not uniformed; we noticed a tendency of simply using the approach which yields numerically better survival estimates.ConclusionThe population-based cancer relative survival, which is continually reported by recognised research groups, could not be compared directly as the methodology is different, and, consequently, final country scores differ. A uniform survival measure would be of great benefit in the cancer care surveillance.

Cancer Patients’ Survival: Standard Calculation Methods And Some Considerations Regarding Their Interpretation

Institute of Oncology Ljubljana, Epidemiology and Cancer Registry, Zaloska 2, 1000 Ljubljana,

Slovenian Journal of Public Health

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

POPULACIJSKO PREŽIVETJE BOLNIKOV Z RAKOM: UPORABA RAZLIČNIH PRISTOPOV IN PROBLEMI INTERPRETACIJE REZULTATOV

BackgroundCancer patients’ survival is an extremely important but complex indicator for assessing regional or global inequalities in diagnosis practices and...

Cancer Patients’ Survival: Standard Calculation Methods And Some Considerations Regarding Their Interpretation

Article Category: Review article

Published Online: Feb 11, 2016

Page range: 144 - 151

Received: May 18, 2015

Accepted: Nov 13, 2015

DOI: https://doi.org/10.1515/sjph-2016-0012

Keywords
cancer survival, population-based survival analysis, cancer registries, relative survival, bias

© National Institute of Public Health, Slovenia

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Cancer Patients’ Survival: Standard Calculation Methods And Some Considerations Regarding Their Interpretation

Article Category: Review article

Published Online: Feb 11, 2016

Page range: 144 - 151

Received: May 18, 2015

Accepted: Nov 13, 2015

DOI: https://doi.org/10.1515/sjph-2016-0012

Keywordscancer survival, population-based survival analysis, cancer registries, relative survival, bias

© National Institute of Public Health, Slovenia

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
cancer survival, population-based survival analysis, cancer registries, relative survival, bias