Abstract
Background
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.
Methods
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.
Results
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.
Conclusion
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.
Breast cancer is increasingly diagnosed in the early stages without regional nodal involvement. The aim of the present study was to determine the 5-year overall (OS) and breast cancer specific ...survival (BCSS) for patients with node-negative breast cancer treated at the University Medical Centre Maribor, and compare it with survival at the national level.
Medical records were searched for information on patients with lymph node-negative invasive breast cancer who received primary treatment at the University Medical Centre Maribor in the period 2000-2009. Information on all Slovenian node-negative breast cancer patients diagnosed in the same period was obtained from the Cancer Registry of Republic of Slovenia. Time trends in survival were assessed by comparing the periods 2000-2004 and 2005-2009.
The 5-year OS and BCSS of patients treated in Maribor in the period 2000-2009 were 92.3% (95% CI, 90.5%- 94.1%) and 96.4% (95% CI, 95.2%-97.6%), respectively, and did not differ from the corresponding OS and BCSS for Slovenian patients. Although the improvement in OS for patients from Maribor diagnosed in the period 2005-2009 compared to 2000-2004 did not reach statistical significance (HR 0.73; 95% CI, 0.51-1.05; p=0.086), BCSS significantly improved over the same time periods (HR 0.53; 95% CI, 0.30-0.94; p=0.028).
Survival of node-negative breast cancer patients treated at the University Medical Centre Maribor is comparable to survival of corresponding patients at the national level. The rising number of long-term breast cancer survivors places additional importance on survivorship care.
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