To monitor key health indicators, most developed countries have established routine data collection systems. The process of collecting and processing these data is called registration, and the central database containing information on specific categorised entities is called a registry. Cancer registries collect and process data on people with cancer. Since 1950, the Slovenian Cancer Registry has been collecting, storing and processing data on all new cases of cancer among residents with permanent residence in Slovenia.

The main sources of data are Slovenian public healthcare institutions, where diagnostics, treatment, and follow-up of patients are carried out, as cancer reporting is required by law. In the past, healthcare providers submitted cancer data to the Slovenian Cancer Registry using special Cancer Notification Form. In accordance with the goals of the National Cancer Control Programme 2017–2021, we began implementing active registration in 2019, whereby the Slovenian Cancer Registry obtains data on the disease and patient care directly from providers’ electronic health records. We are gradually phasing out passive reporting via Cancer Notification Forms.

During the registration process, data in the Slovenian Cancer Registry are entered by specially trained registered nurses in accordance with international, national and internal guidelines. The Slovenian Cancer Registry follows all patients until death, which enables the calculation of additional disease burden indicators such as survival and prevalence.

When calculating most cancer burden indicators, data on the number of residents and their age structure are just as crucial as patient data. For Slovenia, these data for census years have been available throughout the entire period of cancer registration. Population censuses were generally conducted approximately every ten years. For the interim periods up to 1985, our calculations assumed an unchanged age structure between two censuses. Since the mid-1980s, when population numbers have been monitored on an ongoing basis, we have used up-to-date data on the number and age structure of the population. In our annual reports, we use the situation as of 1 July of each year as a reference, which we obtain from the SI-STAT data portal of the Statistical Office of the Republic of Slovenia.