According to the estimates of the Global Cancer Observatory (GLOBOCAN), Hungary has among the highest all-cancer incidence rates in the world (321.6), which highlights the necessity for a population-based cancer registry [1]. The Hungarian National Cancer Registry (HNCR) has operated from the 1950s, although its legal basis was established only in 1999. In that year a regulation order of the Ministry of Health authorized national cancer registration to commence at the National Institute of Oncology (NIO) to support national oncology services and cancer planning. Population-based activities launched in 2000, and the HNCR has published annual cancer statistics covering the whole of Hungary thereafter [2], apart from childhood tumors, which are collected by a specialized registry [3]. However, local hospital-based data collections on cancer diseases were present in Szabolcs-Szatmár-Bereg and Vas counties and in the city of Miskolc much earlier (from the 1960s). Since their ceased operation, Hungary has not been represented in the ‘Cancer incidence in five continents’ series since 1987 [4]. According to the 2001 census, the population of the country was 10.2 million, which decreased to 9.8 million by 2019, with males and females comprising 47.8% and 52.2%, respectively, in the latter year [5]. Data transmission is a legal obligation across all 142 healthcare providers in the country, regardless of whether they are private or public institutions. In Hungary, most healthcare costs are financed by the National Health Insurance Fund that covers the whole population. The organization of the state healthcare system is pyramidal, comprising basic care, outpatient specialists, general hospitals, and regional centers. The latter comprise medical universities and national institutes, for which the NIO is the only organization that focuses exclusively on cancer.

Given their key role in cancer control, population-based cancer registries should be able to provide an objective evaluation of the quality of the data collected [6]. With the HNCR playing an increasingly significant role in monitoring the cancer situation in Hungary, we provide the first evaluation of the comparability, completeness, and validity of recent data at the HNCR. Applying the principles and techniques of evaluation described in international guidelines [7], [8], [9], and their practical implementation [10], [11], [12], [13], [14], [15], we provide an overview of data quality at the HNCR in the context of future plans for the registry.