Increasing incidence and survival of corpus uteri cancer in Estonia over the past two decades
Introduction
Corpus uteri cancer was the most common gynecological malignancy in Estonia in 2015 (age-standardized (world) incidence rate (ASIR) 17/100 000 per year) [1]. Globally, the respective rate varies considerably, from below 5/100 000 in some regions of Africa and Asia to over 20/100 000 in Europe and North America [2]. In Europe, corpus uteri cancer is the fourth most common cancer in women (ASIR 16/100 000 per year) [2]. A recent analysis showed decreasing mortality in most European countries for women born before 1940, but not for later birth cohorts [3]. Corpus uteri cancer survival is relatively good: the European average 5-year relative survival in EUROCARE-5 (2000–2007) was 76% (70% in Estonia) [4]. In the US, the latest 5-year survival (2008–2014) was as high as 81% [5]. In the treatment of corpus uteri cancer, multidisciplinary approach has been adopted, whereas surgical treatment has remained the cornerstone of treatment [6].
The majority of corpus uteri cancers consist of endometrial cancers (EC) that are divided into two main subtypes, based on tumour aetiology, histology, prognosis and biomarkers [7,8]. Type I EC is associated with being overweight and obesity and includes mostly endometrioid histology. The etiological factors of type II have not been well established. These tumours have non-endometrioid histology and are mostly oestrogen independent [7,8].
Being overweight has been established as one of the main risk factors for EC [9]. Nulliparity, oestrogen-alone hormone replacement therapy and diabetes as a consequence of being overweight have also shown an unfavourable effect on EC incidence [10].
In view of the increasing prevalence of obesity [11] and previously reported relatively low survival compared to other European countries [4], an in-depth analysis of the epidemiological trends of corpus uteri cancer in Estonia was warranted.
The aim of the study was to evaluate the incidence, mortality and survival trends of corpus uteri cancer in Estonia by age, stage and histological subtypes with an emphasis on surgical treatment.
Section snippets
Materials and methods
Data on incident cases of corpus uteri cancer (International Classification of Diseases, 10th Edition, code C54) diagnosed in 1996–2016 were obtained from the Estonian Cancer Registry (ECR), a population-based registry that covers the whole country with a population of 1.3 million (2011 census) and has data since 1968. Age at diagnosis was categorized into four groups: <55, 55–64, 65–74 and 75 years. Morphology was classified into three types based on International Classification of Diseases
Results
In total, 4281 cases of corpus uteri cancer were diagnosed in Estonia in 1996–2016 (Table 1). The overall percentage of microscopic verification was 98% and this quality indicator remained stable over the study period. Mean age at diagnosis increased from 63 years in 1996–2002 to 66 years in 2010–2016. The proportion of women age ≥75 years increased from 15% to 26%. Type I cancers accounted for 65% of the cases in the earliest period and 85% in the latest period. The proportions of type II and
Discussion
The study showed a significant increase in overall incidence of corpus uteri cancer in Estonia since 2009. This trend derives from patterns seen in type I EC incidence and those of elderly women. Mortality has been stable over the study period. Relative survival improved for type I EC as well as for all age and stage groups. A significant increase was seen in the proportion of surgically treated patients, particularly among older women and later stages.
The main strength of the study was the use
Conclusions
The recent strong rise in incidence was mainly driven by the changes in type I EC and older age groups. The increasing burden of obesity in Estonia is the most likely reason behind these trends and thus, continuing efforts are necessary to tackle obesity and to increase the awareness of corpus uteri cancer risk associated with obesity. The importance of regular gynaecological check-ups, also in the postmenopausal age, should be emphasised to encourage early detection. Survival gains were most
Authorship contribution statement
KO, KI and PV designed the study, KO drafted the manuscript, KI and AB performed statistical analysis, AB prepared the graphics, KO, PV, KI, AB interpreted the results. All authors (KO, PV, KI, AB and HE) critically revised the manuscript for intellectual content and approved the final manuscript.
Funding
This work was supported by the Estonian Research Council [grant no.IUT5-1].
Declaration of Competing Interest
None declared.
Acknowledgements
The authors thank Dr. Margit Mägi and Mrs. Pille Härmaorg from the ECR for providing the data, and Mrs. Tiiu Vahtramäe for technical assistance.
References (37)
- et al.
Trends in corpus uteri cancer mortality in member states in the European Union
Eur. J. Cancer
(2014) - et al.
Survival of women with cancers of breast and genital organs in Europe 1999-2007: results of the EUROCARE-5 study
Eur. J. Cancer
(2015) Two pathogenetic types of endometrial carcinoma
Gynecol. Oncol.
(1983)- et al.
Bokhman redux: endometrial cancer “types” in the 21st century
Gynecol. Oncol.
(2017) - et al.
Body-mass index and incidence of cancer: a systemic review and meta-analysis of prospective observational studies
Lancet
(2008) - et al.
Standard cancer patient population for age standardising survival ratios
Eur. J. Cancer
(2004) - et al.
Sheep and goats: separating cervix and corpus uteri from imprecisely coded uterine cancer deaths, for studies of geographical and temporal variations in mortality
Eur. J. Cancer
(2004) - et al.
Time trends in the incidence of hysterectomy-corrected overall type 1 and type 2 endometrial cancer in Denmark 1978-2014
Gynecol. Oncol.
(2017) - et al.
Improved survival related to changes in endometrial cancer treatment, a 30-year population based perspective
Gynecol. Oncol.
(2012) - et al.
Endometrial cancer in elderly women: which disease, which surgical management? A systematic review of the literature
EJSO
(2016)