Selected trends in head and neck cancer epidemiology in Slovakia - an international comparison.

Background: Head-and-neck malignant neoplasms (diagnosis group C00-C14, according to ICD-10) form a heterogeneous group of diseases with close anatomical localization. The incidence is twice to three times higher in men than in women and is increasing worldwide.

Objective: The aim of our analysis was to estimate changes of incidence and mortality rates of head-and-neck malignancies associated with anatomical topographic regions over the time as well as to compare these indicators in different selected countries of the world. Secondary endpoints included the assessment of patients' age distribution, clinical stages of newly diagnosed cases, and point prevalence of the disease in the Slovak Republic (SR).

Material and methods: The data base for the calculations was obtained from national databases and outputs of the National Cancer Registry (NCR) of the SR (with summary data available from the National Epidemiological Portal of Malignant Tumors, which analyzed data from 1984-2003 and was available until 2009, the remaining data were obtained from annual analyses of the NCR of the SR and the National Centre for Health Information (NCZI)), from the Statistical Office of the SR, and from the IARC WHO global database outputs on incidence, mortality, prevalence and survival of the patients. Incidence and mortality data in the SR were available up to 2012 (including) and up to 2021 (including), respectively. A log-linear joinpoint regression model was used to analyze the development of incidence and mortality rates over time by using Joinpoint Regression Program software. To achieve maximum precision in the estimated total surviving population of patients with head and neck malignant neoplasms, a model was developed to calculate the point (overall) prevalence based on absolute numbers of long-term registered national counts of newly diagnosed patients, mortality from the disease, overall mortality, and survival probability. The representation of clinical stages of head and neck carcinoma in the SR was compiled from available national data (2000-2012) and from predictions and does not consider changes in TNM classifications over the time.

Results: The age-adjusted (to the world standard population, ASR-W) incidence rate and the age-adjusted (ASR-W) mortality rate of head-and-neck malignant tumors in the SR have shown a significantly decreasing tendency in men since 1990; however, in women both of these indicators have shown a significant increasing tendency, especially the significantly growing incidence since 2004. In 2012, the overall age-adjusted incidence and mortality rate of head-and-neck cancers in the SR were significantly higher in males (ASR-W incidence 22.6/100,000 and ASR-W mortality 15.26/100,000) compared to females (ASR-W incidence 4.21/100,000 and ASR-W mortality 1.52/100,000). More than 75% of newly diagnosed cases are already in advanced and metastatic clinical stages, which is the most unfavourable survival factor. The absolute prevalence of these patients in the SR was estimated to be N = 9,395 in the year 2021.

Conclusion: It is necessary to get a current and well evaluated epidemiological overviews to be able to plan preventive and intervention programs in oncology.