Objectives
Non-melanoma skin cancer (NMSC) is the most common malignancy among Caucasian population. In Hungary, annually twice as many cases were registered than the second most frequent colorectal cancer. Despite its malignant dignity, it is only life-threatening in extreme cases. An overview of NMSC incidence can allow insight not only the changing prevalence of global cosmic risk factors and efficiency of Hungarian healthcare system, but also measure the clear impact of COVID-19 pandemic on incidence. For this purpose, our study examines the national population-based incidence by sex, age and histological subtypes from 2000 to 2023 and projected future trends up to 2044.
Materials and Methods
NMSC-specific (ICD-10: C44) record-level data by sex, age and morphology were sorted from the Hungarian National Cancer Registry. Based on morphological codes, the cases were divided into three main clinical subgroups: basal cell carcinoma, squamous cell carcinoma, other or non-specified categories. Descriptive statistical age-standardization was conducted for the period 2000-2023 according to ESP2013, with special attention to the years affected by COVID-19, 2020, 2021 and 2022. Age-standardized NMSC incidence rate predictions by sex based on age-period-cohort (APC) regression model were calculated for the year up to 2044 applying the Nordpred package in R.
Results
In 2023 NMSC was diagnosed in slightly more women than men and approximately three-quarters of cases were basal cell, 16% squamous cell carcinoma and 9% of other or unknown subtype. From 2000, stagnation in age-standardized incidence can be observed up to 2010, which turns into a rapid +50% growth by 2019. Compared to 2019, the impact of COVID-19 has substantially reduced the number of detected cases by 25% and 17% in 2020 and 2021, respectively. Then significant rebound was visible in 2022 and 2023. All ages - except for the youngest studied 30-34-year old group - contributed to the 2020 break in the time series, mostly elderly people aged 65-79 and 85+. This fall and rebound effect were exclusively present among basal cell carcinoma patients, not among squamous cell cancer and other subtypes. Excluding the effect of COVID-19, until 2044 37.5% increase was projected in the incidence of NMSC for both sexes, particularly due to the rise in the 60-64 and the oldest 80+ age groups. However, COVID-19 had an immense impact on the predictive model. 
Conclusions
In Hungary, only the diagnosis of basal cell cancer was affected by COVID-19 pandemic, the incidence of other skin cancer types remained in the expected level. This fact confirms only minor dysfunction during the COVID-19 period. It can be seen that for both genders, the diagnosis of basal cell cancer was delayed the most by more than a year for those in their 40s, and for women aged 65-69 and men aged 60-64. Considering only the changing age composition in the NMSC discovery in our prediction, sharp increase in NMSC cases will continue even after the COVID-19 pandemic and going to mitigate from only 2035 onwards. On the other hand, new predictive models should be introduced that incorporate the effect of pandemic lock-downs.