An assessment of GLOBOCAN methods for deriving national estimates of cancer incidence

To validate the nine methods used in GLOBOCAN to estimate national incidence in 2012 (GLOBOCAN 2012), long-term na-tional and regional incidence and mortality data as well as 5-year relative survival estimates are required. Of the few countries with such data available, we selected Norway because of the consistently high quality of its cancer registry data, available nationally and by region. Cancer reporting is a legal requirement in Norway and data linkage procedures with the cause of death registry further increase the completeness of the information. For the period 2001-2005, data completeness was estimated at 98.8%, while 93.8% of the cases had been verified by examining biopsy samples under a microscope. rom the Nordic cancer database NORDCAN, we extracted Norwegian incidence and mortality data by region, year of diagnosis, cancer site, sex and 5-years age group (starting at 0-4 and ending at 85+) for the period 1983-2012. We also extracted Norwegian 5-year relative survival proportions for each cancer site as well as incidence and mortality data from neighbouring countries Denmark, Finland, Iceland and Sweden. As with GLOBOCAN 2012, national population data were obtained from the United Nations 6 while regional population data were extracted from NORDCAN. Unspecified neoplasms of the uterus (ICD-10 code C55) were reallocated to the cervix (C53) and corpus uteri (C54) according to the respective proportions of these two sites in the different datasets. e computed the number of cases by sex and cancer site in Norway in 2010 as the average of the recorded cancer cases between 2009 and 2011 to define a gold standard for comparisons. We then applied each of the nine methods used in GLOBOCAN 2012 to estimate the number of cancer cases in Norway in 2010, by sex and cancer site, and compared these estimates with the gold standard.