print

Epidemiology of breast cancer in the Czech Republic

Mužík J.¹, Dušek L.¹, Abrahámová J.², Koptíková J.^1
1 Institute of Biostatistics and Analyses, Masaryk University, Brno, Czech Republic
² Thomayer University Hospital, Prague, Czech Republic

Malignant tumours present a serious health issue in the Czech Republic, particularly with respect to the ever growing number of newly diagnosed cancer patients each year. Cancer epidemiology is very helpful in our understanding of this issue, making it possible for us to assess the population burden, to point out high-risk groups within the population, to assess the effectiveness of diagnosis and treatment, and to predict the numbers of cancer patients, which is essential to plan the health care costs in future. However, the availability of sufficiently extensive and complete population-based data is an essential prerequisite for the successful application of cancer epidemiology. Thanks to the Czech National Cancer Registry, which has been maintained and updated in a standardized manner since 1976, such data is available for the Czech Republic, covering the entire period from 1976 to 2005 (as on January 2008). The Czech National Cancer Registry contains records on all diagnosed cancers in the Czech population; this article deals with the most important diagnosis within the female population – the malignant neoplasm of breast (i.e., breast cancer).

Breast cancer incidence and prevalence in women

Breast cancer is the most common cancer* in Czech women, accounting for 17% of all newly diagnosed malignancies in the female population. The incidence trend in the entire monitored period has continuously increased (see Figure 1) – apart from the last few years when it has stabilised and even decreased. A total of 5,533 women were diagnosed with breast cancer in 2005, representing 105.4 breast cancer patients per 100,000 women (see Table 1). In terms of prevalence, 49,539 women were alive in the Czech Republic who have had a diagnosis of breast cancer, representing 944 patients per 100,000 women.

High incidence of breast cancer is typical for economically developed countries, particularly for those of Northern and Western Europe and of North America. Czech breast incidence rates per 100,000 women rank 23th among European countries, while mortality rates rank 17th (see Table 2).

Note: * excluding non-melanoma skin cancer

Breast cancer mortality in women

Breast cancer not only presents the major cancer incidence burden of the female population – it is also the most common cause of death from cancer in women. Approximately 1950 Czech women are dying of breast cancer each year, representing 37 deaths per 100,000 women. Overall, breast cancer was responsible for 3.6% of all deaths in Czech women in the period 2000–2005 (see Table 3 and Table 4). Despite the ever growing incidence of breast cancer, mortality has been stable in the long term (see Figure 2), which unequivocally demonstrates an improvement in treatment success, particularly thanks to a higher proportion of tumours detected at early clinical stages.

Age of women with breast cancer

Breast cancer risk is strongly related to age, with incidence rates rising considerably after the age of 40. In the period between 2001 and 2005, around 50% of cases were diagnosed in the 53-73 age group, with the median age of 62 years (see Figure 3).

In terms of incidence trends, the most significant increase between periods 1991–1995 and 2001–2005 has been reported for women aged 50-59 years (by 34%) and 60-69 years (by 24%). The growing trend is also apparent in women aged 40-49 and those aged 70 and over, but it is less significant in these age groups (an increase by 13-17%). The incidence trend in women under the age of 39 can be described as stable in time (see Figure 4 and Table 5). A significant increase in breast cancer incidence in women aged 60-69 after the year 2002, as it is apparent from Figure 4, can be partly attributed to a higher detection rate of malignant tumours due to the breast screening programme which was launched at that time. The Czech National Breast Screening Programme is primarily aimed at women aged 45-69; more detailed information about the programme can be found on this website.

In terms of age structure of breast cancer patients, there has been an increase in the proportion of 50-59 age group between 1996 and 2005, a decrease in the proportion of patients under 49 years, while the proportion of breast cancer patients aged 60 and over was rather stable (see Figure 5). It is important to remember, however, that the age structure of patients’ population is closely linked to the age structure of the entire population, which also changes over time. Therefore, the age-specific incidence (i.e., number of cancer cases per 100,000 population in a given age category) is more suitable for the assessment of incidence trends.

Breast cancer diagnosis – tumour morphology and clinical stage of the disease

Basic characteristics of a newly diagnosed tumour involve its morphological type, biological behavious (malignant or benign), exact location (topography) and stage of the disease. According to data from 2000–2005, ductal carcinoma is the most common type of breast cancer in women (73% of cases), followed by lobular carcinoma (14% of cases) (see Table 6).

Clinical stage of any malignant neoplasm is one of the crucial characteristics needed to estimate the prognosis and to choose the right treatment strategy. The clinical stage is determined according to exactly specified rules which are stipulated in the so-called TNM classification of malignant tumours. According to pre-defined types of examination, the tumour is described with three parameters: T – size of the primary tumour, N – degree of spread to regional lymph nodes, N – presence of metastases in distant organs (beyond regional lymph nodes). These parameters are then employed to establish the clinical stage of the disease. Stages 1 and 2 are referred to as “early”, with a good prognosis and high treatment success; advanced stages 3 and 4, however, represent a high-risk group with a significantly poorer prognosis. The trend in the proportion of early stages among newly diagnosed breast cancers in Czech women has been rising over the entire monitored period. This trend has stabilised between 2002-2005 with 31-35% of cases in stage 1 and 32-39% of cases in stage 2 (see Figure 6). The introduction of modern diagnostic methods (such as mammography) have significantly contributed to the high proportion of early-detected clinical stages, combined with the nationwide use of those methods within the Czech National Breast Screening Programme (this website provides more detailed information about the programme).

Breast cancer in young women

Although the majority of breast cancer cases occcurs in middle-aged and elderly women, it can also affect young women. The incidence is extremely low in very young women (only 9 cases have been recorded over the entire monitored period since 1977), but it grows slowly after the age of 20. In the long term, approximately 7 breast cancer patients per 100,000 women are reported each year among women aged 20-34, and this trend can be considered as stable despite short-term fluctuations (see Figure 7). Between 2004 and 2005, breast cancer incidence in women aged 20-34 was 86 cases per year, corresponding to 7.2 cases per 100,000 women in this age group, and representing the 3rd most common cancer in young women (after cervical cancer and non-melanoma skin cancer). The majority (88%) of newly diagnosed breast cancers are ductal carcinomas, and breast cancer is most frequently diagnosed at early stages 1 or 2 in this age group (74% of cases). Breast cancer mortality in women aged 20-34 is approximately 10 deaths per year, which corresponds to 0.8 deaths per 100,000 women in this age group (see Table 7).

Breast cancer in elderly women

With the ageing population, the number of breast cancer patients aged 70 and over has gradually increased. In the long term, the incidence trend in this age group has increased, although it has somewhat stabilised over the last few years (see Figure 8). The proportion of these elderly women among patients with breast cancer has ranged between 30 and 35% over the entire monitored period (since 1977). Between 2004 and 2005, breast cancer incidence in women aged 70 and over was 1776 cases per year, corresponding to 275 cases per 100,000 women in this age group, and representing the 3rd most common cancer in elderly women (after non-melanoma skin cancer and large bowel cancer). In the same period, breast cancer mortality in women aged 70 and over was 1051 deaths per year, which corresponds to 163 deaths per 100,000 women in this age group (see Table 8).

Breast cancer in men

Although the vast majority of breast cancer cases occur in women, this disease can also affect men. Breast cancer in men, however, only occurs rarely, with an incidence of around 44 newly diagnosed cases per year (i.e., 0.88 cases per 100,000 men), accounting for only 0.13% of all cancers in men. The median age of male patients with breast cancer is 67 years, and around 50% of male patients are aged 60-74 (see Table 9), which is a significantly higher age than that of female patients.

List of Figures

• Figure 1: Trend in breast cancer incidence (Czech Republic, females)
• Figure 2: Trend in breast cancer mortality (Czech Republic, females)
• Figure 3: Age of breast cancer patients in years 2001-2005 (Czech Republic, females]
• Figure 4: Trend in breast cancer incidence, by age categories (Czech Republic, females)
• Figure 5: Trend in age structure of breast cancer patients (Czech Republic, females)
• Figure 6: Proportion of clinical stages in newly diagnosed breast cancer patients (Czech Republic, females)
• Figure 7: Trend in breast cancer incidence in the 20-34 year group (Czech Republic, females)
• Figure 8: Trend in breast cancer incidence in those aged 70 and above (Czech Republic, females)

List of Tables

• Table 1: Incidence and prevalence of breast cancer (Czech Republic, females)
• Table 2: Incidence of breast cancer in Czech women, compared to other countries
• Table 3: Causes of death in the population of Czech women (data from 2000-2005)
• Table 4: Mortality of breast cancer (Czech Republic, females)
• Table 5: Incidence of breast cancer, by age categories and time periods (Czech Republic, females)
• Table 6: Morphological types of breast cancer (Czech Republic, females, data from 2000-2005)
• Table 7: Breast cancer in young patients, aged 20-34 years (Czech Republic, females, data from 2004-2005)
• Table 8: Breast cancer in elderly patients, aged 70 years and above (Czech Republic, females, data from 2004-2005)
• Table 9: Breast cancer in Czech male population (data from 2000-2005)

References

1. Abrahámová J., Dušek L. (eds). (2003): Metody včasného záchytu karcinomu prsu. GRADA Publishing a.s., Praha 2003. 227 s., ISBN 80-247-0499-4.
2. Demografické údaje České republiky a Databáze zemřelých České republiky, Český statistický úřad
3. Dušek L., Mužík J., Kubásek M., Koptíková J., Žaloudík J., Vyzula R.. Epidemiologie zhoubných nádorů v České republice [online]. Masarykova univerzita, [2005], [cit. 2008-8-26]. Dostupný z WWW: http://www.svod.cz. Verze 7.0 [2007], ISSN 1802-8861.
4. J. Ferlay, F. Bray, P. Pisani and D.M. Parkin: GLOBOCAN 2002: Cancer Incidence, Mortality and Prevalence Worldwide. IARC CancerBase No. 5. version 2.0, IARCPress, Lyon, 2004, http://www-dep.iarc.fr
5. ICD-O-2: International Classification of Diseases for Oncology, 2nd Edition, World Health Organization, 1990; MKN-O-2: Mezinárodní klasifikace nemocí pro onkologii, Druhé vydání, Česká verze, Ústav zdravotnických informací a statistiky ČR, Praha 1994
6. International Union Against Cancer (UICC): TNM Classification of malignant tumours. 5th ed. Sobin LH, Wittekind Ch (ed.), New York, Wiley-Liss. 1997; TNM klasifikace zhoubných novotvarů, 5. vydání 1997, Česká verze, Ústav zdravotnických informací a statistiky ČR, Praha 2000, ISBN 80-7280-025-6
7. Mamografický screening v České republice. [online], [cit. 2008-8-26], Dostupný z WWW: http://www.mamo.cz
8. Národní onkologický registr České republiky, Ústav zdravotnických informací a statistiky ČR, data z let 1977–2005
9. Tumours of the breast and female genital organs, WHO classification of tumours, 2003, ISBN 92-832-2412-4
10. Ústav zdravotnických informací a statistiky ČR, Novotvary (Cancer Incidence in the Czech Republic); vydáváno každoročně, poslední vydání: rok 2005, ISBN 978-80-7280-723-9, dostupné z http://www.uzis.cz/download.php?ctg=10&search_name=Novotvary&region=100&kind=1&mnu_id=5300

This text has been adapted from the Czech article “Stručný přehled epidemiologie zhoubného novotvaru prsu v České republice”, which was published in the Czech journal Onkologie (2009/01).