Cutaneous squamous cell carcinoma 1986 - 2019 in Germany: Incidence, Localization, Staging, and Histologic Types

Background

Cutaneous squamous cell carcinoma (cSCC) is the second most common non-melanoma skin cancer and is associated with considerable morbidity. Population-based data analysis in Germany has largely focused on incidence and trends.

Objectives

To assess incidence, anatomical site- and T-stage distribution, histological subtypes of cSCC in Germany, with a focus on sex- and age-group specific patterns and regional differences.

Methods

A total of 213,935 first primary invasive cSCC cases diagnosed between 1986 and 2019 were analysed from four federal states of Germany with complete case ascertainment. Crude and age-standardized incidence rates (CIR, ASIR) were calculated, and subgroup analyses were performed by sex, anatomical site, histological subtype, and T-stage and region.

Results

CIR increased by over 500 % from 1986 to 2015, with a steeper rise in women. Incidence plateaued after 2015 in most states, except for a delayed increase in Saarland. The face (ICD-10 C44.3) was the most frequent tumor site showing equal incidence in males and females. T1 tumors predominated (88.6 %), although staging data were incomplete in 33.5 % of cases. Regional and sex-based differences were observed in both T-stage and histological subtype distribution. Spindle cell and non-keratinizing variants were associated with more advanced stages. Cancer registry data did not count more than one cSCC and carcinoma in situ such as Bowen’s disease or actinic keratosis, leading to systematic underestimation of disease burden.

Conclusions

cSCC incidence has risen substantially in Germany, with significant variation by sex, region, and tumor type. Improved registry protocols incorporating multiple primaries, clinical staging, and early in situ lesions are essential for accurate surveillance and healthcare planning.

Plain Language Summary

How common is squamous cell skin cancer in Germany and how does it behave?

We looked at cutaneous squamous cell carcinoma (cSCC), a common skin cancer that starts in the flat cells on the skin’s surface. It is the second most common skin cancer and the second most common cancer, affecting tens of thousands of people in Germany each year.

We found that the registration of new primary cSCC tumors increased more than fivefold between 1986 and 2015. However, incidence rates plateaued from 2015 to 2019. Tumors most often appeared on the face, but the distribution by site differed between men and women. Men developed cSCC at younger ages and more frequently than women. Approximately 90% of tumors were diagnosed at an early stage, but staging information was missing for about 34% of cases.

cSCC develops on chronically sun-damaged skin, and patients often have more than one tumor. There are also early skin changes that require treatment. Because cancer registries count only one tumor per person and ignore these early lesions, the true burden of treating patients with chronic sun damage is underestimated.

We concluded that cSCC has become more common in Germany, with clear differences by sex, age, and region. Improving cancer registries to record all tumors will provide a more accurate picture of stage and subtype distribution. Recognizing high-risk groups, will help guide prevention, screening, and earlier treatment strategies.

What is already known about this topic?

Cutaneous squamous cell carcinoma (cSCC) is the second most frequent malignancy overall as well as the second most frequent skin tumor. Epidemiological research has long focused on Basal Cell Carcinoma (BCC) and cSCC conclusively. Recent research has addressed major differences in their epidemiology, highlighting differnces in incidence rates across genders and age groups. The largest data set on squamous cell carcinoma analysed so far was 145.000 cases.

What does this study add?

This study provides conclusive results on incidence, localization, tumor stages and histologic types comparing men, women and age groups based on large scale data with over 200,000 primary tumors over a period of more than 30 years.

What is the translational message?

Identification of gender- and age-specific risk patterns in cSCC enables the formulation of targeted prevention strategies, screening recommendations, and earlier diagnosis and optimized management of high-risk populations. The burden of morbidity and tumors associated with chronic actinic damage remains underestimated in current literature and cancer statistics. Demographic changes are expected to increase the disease burden substantially, although the exact magnitude remains uncertain.