Elsevier

Cancer Epidemiology

Volume 62, October 2019, 101566
Cancer Epidemiology

Increasing incidence and survival of corpus uteri cancer in Estonia over the past two decades

https://doi.org/10.1016/j.canep.2019.101566Get rights and content

Highlights

  • Corpus uteri cancer incidence and survival were studied by morphology and FIGO stage.

  • Rapid increase in incidence was seen since 2009.

  • The incidence rise was driven by trends in type I cancer and age groups ≥65 years.

  • Large survival increases were seen overall, for stage IV cancers and older women.

  • Survival improvements were most likely related to more frequent surgical treatment.

Abstract

Background

Corpus uteri cancer has become the fourth most common female cancer in Europe. In Estonia, the prevalence of obesity is increasing, and corpus uteri cancer survival has been relatively low. The aim of the study was to evaluate incidence, mortality and survival trends of corpus uteri cancer in Estonia by age, stage and histological subtypes with an emphasis on surgical treatment.

Methods

Estonian Cancer Registry data on incident cases of corpus uteri cancer were used to examine incidence trends (1995–2016) and calculate relative survival ratios (RSR) (1996–2016). Cases were classified by morphology and FIGO stage. Causes of Death Registry data were used to analyse corrected mortality (1995–2017).

Results

A total of 4281 cases were diagnosed in 1996–2016. A significant increase was seen in age-standardized incidence from 2009, while mortality remained stable throughout the study period. Significant increases were observed for type I cancers and age groups ≥65 years. Overall age-standardized 5-year RSR improved from 70% in 1996–2002 to 78% in 2010–2016. Survival increased for type I cancers, all age groups and all stages (significantly for stage IV). The proportion of surgically treated cases increased significantly from 85% to 89%, with the largest increases seen in older age groups and later stages.

Discussion

The rising corpus uteri cancer incidence in Estonia is driven by the type I cancer trend. Survival gain for later stages and older age groups likely reflected more frequent surgical treatment. To reduce mortality, further efforts are necessary to ensure appropriate care for all patients.

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.

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