Change in the age structure of newly diagnosed cancer patients between 2010 and 2022 in private practices

Cancer is one of the leading causes of death worldwide and will be responsible for almost 10 million deaths in 2020. In the same year, approximately 19 million new cases of cancer were diagnosed worldwide [1]. The incidence of all cancers increased between 1998 and 2012 in most countries and in all age groups worldwide [2]. However, at least in Europe, the USA and part of Asia, this trend corresponded to demographic changes and the aging of the population [3,4]. The risk of cancer increases with age, and more than 60% of cancers are diagnosed in people aged 65 years or older [5]. However, recent studies indicate a sharp increase in the incidence of cancer in adults under 50 years of age [6-15]. Young people diagnosed with cancer often have more advanced disease at the time of diagnosis than older people, in part due to delayed diagnosis [16].

>> In the United Kingdom (UK), the cancer incidence rate increased by 22% in 2016-2018 compared to 1993-1995 among those aged 25 to 49, while it increased among those aged 50 to 74 and those aged 75 and over increased by 13% or 9% [10]. Sung et al. reported emerging cancer trends among young adults in the United States. Specifically, from 1995 to 2014, the cancer incidence increased for six of twelve cancer types (multiple myeloma, colorectal cancer, uterine cancer, gallbladder, kidney and pancreatic cancer) in people aged 25 to 49 years [8].
In the United States, colorectal cancer rates among individuals aged 20 to 49 years increased from 2001 to 2017, with the fastest increase observed from 2012 to 2017 [6]. Gu et al. reported an increase in global incidence and mortality rates of young-onset colorectal cancer over the past three decades [11]. In the Netherlands, too, the incidence of colorectal cancer at younger ages has increased by 0.7–2.1% in recent decades [12]. For Germany, Tanaka et al. Data on colon cancer incidence were obtained from the German Center for Cancer Registry data, showing an annual increase in colon cancer incidence at younger ages of 1.2% in men and 1.3% in women [14]. Vuik et al. Finally, data from 144 million people aged 20 to 49 from 20 European countries showed that between 2004 and 2016, the incidence of colorectal cancer in the 20 to 29 year old, 30 to 39 year old and the 20 to 39 year old age groups 40 to 49 year olds increased by 7.9%, 4.9% and 1.6% per year [15].
Although large epidemiological studies have been conducted from various countries and are of great scientific value, studies from Germany are limited. In addition, several of the studies cited focused on colorectal cancer or cancer overall, with incomplete data on changes in the incidence of other cancers. The aim of the present study was to determine the age of new cancer patients in 2010 and 2022 and to evaluate the changes in the proportion of cancer cases at younger ages in the total cancer cases in private practices.
methods
This study is based on data from the Disease Analyzer Database (IQVIA), which contains basic demographic data, diagnoses and drug prescriptions obtained directly and in an anonymized form from computer systems in the practices of general practitioners and specialists [17]. The database covers around 3-6% of all outpatient practices in Germany. It has already been shown that the practices contained in the Disease Analyzer database are representative of the general practitioners in Germany [17]. Finally, this database has already been used in previous studies focusing on cancer [18-20]. The database used only contains anonymized data that complies with the provisions of applicable data protection laws.
This retrospective cross-sectional study included adult patients (≥18 years) with a first documented cancer diagnosis (ICD-10: C00-C97) in 557 private practices in Germany in 2010 or 2022. These practices included 305 general practitioners and internists , 50 dermatologists, 95 gynaecologists, 34 urologists, 54 ENT doctors, eight pneumologists and 11 gastroenterologists. Only practices that provided continuous data in 2010 and 2022 were included to enable a comparison of the two time periods.
We analyzed the mean age at first cancer diagnosis and the proportions of the three age groups (18-49, 50-65, and >65) in 2010 and 2022. Differences between the mean ages in 2010 and 2022 were tested using Wilcoxon rank tests, and the proportions of the three age groups 2010 and 2022 with chi-square tests. These analyzes were conducted both for cancer overall and for eight major cancer groups separately, including digestive organs, respiratory organs, skin, female breast, female genital organs, prostate, urinary tract, lymphomas and leukemias. A P-value of <0.05 was considered statistically significant. Analyzes were performed using SAS version 9.4.
Results
Table 1 shows the patient numbers available for analysis. A total of 38,857 patients were diagnosed with cancer for the first time in 2010 and 36,636 in 2022. The most common type of cancer was skin cancer (12,331 in 2010 and 12,952 in 2022), followed by breast cancer (4,593 in 2010 and 4,503 in 2022) and digestive organ cancer (4,271 in 2010 and 3,443 in 2022).
Figure 1 shows the average age at the first documented cancer diagnosis in 2010 and 2022. The average age of individuals at the first cancer diagnosis was significantly lower in 2010 (64.0 years, standard deviation (StA): 14.6 years) compared to 2022 (67.9, StA: 14.7, p<0.001). The average age at the first cancer diagnosis increased significantly in patients with all types of cancer. The largest increase was observed in breast cancer from 55.2 (StA: 18.1) years in 2010 to 63.2 (StA: 15.2) years in 2022, p < 0.001, followed by skin cancer from 63.4 ( StA: 15.2) years in 2010 to 68.2 (StA: 15.3) years in 2022, p<0.001) and lymphomas from 62.2 (StA: 16.2) years in 2010 to 65, 8 (StA: 16.2) years in 2022, p<0.001 (Fig. 1).
All differences between 2010 and 2022 are significant at p<0.001
Figure 2 shows the proportions of patients with new cancer diagnoses in the three age groups. The proportion of cancer cases at the age of 50 years fell significantly from 17.3% in 2010 to 10.9% in 2022 (p<0.001). The largest relative decrease was observed in prostate cancer (1.7% to 0.8%, p<0.001), followed by cancer of the female genital organs (37.6% to 18.4%, p<0.001) and skin cancer (21.4% to 11, 8%, p<0.001, Figure 2). Interestingly, we observed an increase in the proportion of new cancer diagnoses in the 50-65 age group (27.8% to 29.0%, p<0.001 for cancer overall, 27.3% to 36.4%, p<0.001 for breast cancer, 25.4% to 29.1%, p<0.001 for leukemia, 25.2% to 27.6%, p<0.001 for skin cancer, and 36.0% to 38.8%, p<0.001 for breast cancer, Figure 2). Finally, the proportion of patients over the age of 65 increased from 54.8% in 2010 to 60.0% in 2022 (p<0.001). The largest increase in this age group was seen in cancers of female genital organs (35.1% to 45.2%, p<0.001), skin cancer (53.4% to 60.6%, p<0.001) and lymphoma (50.8% to 56.4% , p<0.001).
discussion
The results of our study, which analyzed 75,493 patients with a new cancer diagnosis, show that the average age at the time of cancer diagnosis and the proportion of patients who were younger than 50 years at diagnosis increased significantly compared to 2010 have fallen. At the same time, the proportion of cancer patients between the ages of 50 and 65 has increased. However, the results refer exclusively to the figures from established practices.
This study did not confirm previous reports of an increase in extremely young cancer patients. Emrich & Kraywinkel and colleagues showed that the incidence of patients with rectal cancer in the age groups 20-29, 30-39 and 40-49 years increased significantly between 2003 and 2016 in Germany. However, only about 7% of the patients were under 50 years old [21]. Similarly, Vuik et al. found that from 2004 to 2016, the incidence of colorectal cancer increased by 7.9% per year in people aged 20-29 years, by 4.9% in people aged 30-39 years, and by 1 in people aged 40-49 years ,6% increase [15]. The differences between our data and the previous data are not easy to explain. The different methods could have played a role. While the earlier studies were classic epidemiological register studies, the analyzes presented here used data from 305 general practitioners and internists, 50 dermatologists, 95 gynecologists, 34 urologists, 54 ENT doctors, eight pneumo -
log:innen and 11 gastroenterologists in Germany examined. It can therefore be assumed that different collectives were examined, which could explain the differences. Interestingly
However, our data is very consistent; the trend towards older age can be seen in all tumor types examined and is supported by the lower proportion of very young patients and the increase in middle-aged patients. The fact that only practices that continuously provided data in 2010 and 2022 speaks for the integrity of our data.
In Germany, all new cancer cases are systematically registered in population-based cancer registries according to federal and state law. The data from the cancer registries of the federal states is reported annually to the German Center for Cancer Registry Data at the Robert Koch Institute (RKI), which regularly carries out analyzes of cancer incidence, prevalence and survival rates. The results are published regularly [22,23]. The median age of all cancer patients at diagnosis was 69 years for women and men in 2010 [22] and 69 years for women and 70 years for men in 2018 [23]. Even if the data from 2022 have not yet been published by the RKI, the results from 2010 and 2018 indicate that the age in Germany as a whole has not changed in this decade, in contrast to the results of our study. However, this can mean that the proportion of young cancer patients in the established practices is decreasing, while it has remained constant in Germany as a whole. This raises the question of whether cancer tends to be overlooked in younger patients or whether resident oncologists and hospitals, who are not covered in the database used, play a greater role in this age group. However, it can at least be assumed that the proportion of younger cancer patents has not increased in recent years.
When considering similarities or differences compared to publications from abroad, the differences between health systems must be taken into account. Cancer screening tests are widespread in Germany, and routine screening and early detection programs have recently become part of health insurance benefits. Statutory health insurance covers preventive examinations for various types of cancer, including genital, colon, breast, prostate and skin cancer. The aim of screening tests is to detect cancer at an early stage and prevent its development by detecting and treating cellular abnormalities such as dysplasia or polyps. Skin cancer screening is offered from the age of 35, cervical cancer screening from the age of 20 and breast cancer screening from the age of 30 [24]. The number of younger cancer patients may have decreased in recent years due to increased participation in cancer screening tests in Germany, which may not be the case elsewhere. While uptake of available cancer screening programs could explain the lower incidence in younger patients for some cancers, it cannot explain the lower incidence in younger patients for cancers for which there is no effective early detection, such as lymphoma or leukemia.
In addition, cancer risk behavior may also vary from country to country. Recently, it has been shown that obesity-related diseases are increasing significantly, especially among young people. The epidemiological spread of obesity and its complications can be observed in all Western countries, although to varying degrees [25]. In Germany, 9.2% of all people with statutory health insurance were diagnosed with obesity in 2009. This proportion increased continuously to 11.2% in 2018, during which time the frequency of obesity diagnoses increased sharply, especially in the older age groups from 80 years [26]. Here, too, different structures and support services of the respective healthcare systems can explain differences in the age at which cancer is diagnosed. The same applies, for example, to certain primary prevention measures such as HPV vaccination, which is accepted differently in the respective countries [27].
In Germany, the proportion of smokers has fallen continuously over the past ten years, especially those under 25 smoke less than their peers in previous decades [28]. The prevalence of smoking among adults aged 18 to 79 has declined overall in Germany over the last 20 years. This decline is mainly due to changes in the younger age groups [29]. This could lead to a decrease in the incidence of respiratory cancers, but also the incidence of other cancer diagnoses in younger patients, over time.
Germany also has the most members in Europe with a total of 11.1 million fitness club members, followed by Great Britain, France, Italy and Spain. In addition, Germany and France recorded above-average membership growth rates in 2018 [30].
We must acknowledge some limitations to our study. First, using ICD-10 codes to document all diagnoses could potentially lead to misclassification and undercoding of certain diagnoses. Our study focused exclusively on the relationship between age and cancer incidence, as we did not have any information about the socio-
economic status, environmental factors, lifestyle habits (such as alcohol and nicotine consumption) and mortality data that would have enabled a more comprehensive analysis. Another limitation is the lack of hospital data, as some patients may only be diagnosed in hospital and no longer visit an office-based practice if they die within a short time of cancer diagnosis. In addition, data on TNM status and staging were not available for the cancer diagnoses. There was no information about ethnicity and skin color that may be associated with skin cancer risk.
Although the results of our study are consistent with previous research indicating higher cancer incidence rates in older patients, we cannot establish causal relationships, only associations. However, the strength of our study lies in the large number of patients and the use of representative data.
In summary, we present the first data from a large database from Germany, which indicate that the mean age at cancer diagnosis in private practices in Germany has increased significantly and the proportion of patients with cancer at younger ages has decreased. A comparison with RKI data is necessary as soon as the RKI data for 2022 is published. <<