Epidemiological Pattern of Esophageal Cancer based on the Database Analysis of National Cancer Registry of Ukraine

Background. Esophageal cancer remains a major medical challenge since it belongs to the most aggressive malignant neoplasms, usually diagnosed at a late stage of the disease.


INTRODUCTION
Esophageal cancer as a medical challenge retains its relevance and complexity these days. A comprehensive review of world statistics of 2018 shows that cancer incidence in this location ranks the seventh among all malignant tumors and ranks the sixth in terms of cancer mortality. In the above year, a total of 572,034 new cases and 508,585 causes of death were associated with the disease worldwide [1].
Purpose -Studying the general patterns of time course of esophageal cancer epidemiological status in terms of morbidity and mortality among the adult population of Ukraine within the period from 2014 to 2019. Materials and Methods. General and standardized morbidity and mortality rates resulting from esophageal cancer from 2014 to 2019 throughout Ukraine and in terms of administrative territories per 100 thousand adult population have been researched along with calculating the growth rate. The study was carried out based on the data of National Cancer Registry of Ukraine. Statistical processing of the obtained data was performed by means of generally accepted statistical methods. Results and discussion. The all-Ukrainian incidence of esophageal cancer averaged 4.5 per 100 thousand population. Zhytomyr, Sumy and Chernihiv regions can be considered as the regions with the highest incidence of esophageal cancer. The lowest number of esophageal cancer cases was found in Chernivtsi and Odesa regions of Ukraine. Esophageal cancer mortality rates ranged slightly from 3.3 to 3.6 per 100 thousand population, but it reduced by 8.3% within six years. Monitoring changes of esophageal cancer mortality rate over time, in 2014 and 2019 in Ivano-Frankivsk, Mykolaiv and Rivne regions and in Kyiv it increased by more than 20%. A 30% reduction in mortality was observed in Kirovohrad, Odesa, Kharkiv and Zhytomyr regions. In 2019, Odessa and Kirovograd could be considered the regions with a low mortality rate showing 2.1 per 100 thousand population. In 2018, 88% of esophageal cancer cases were diagnosed in men and only 12% in women. The vast majority of cancer patients were aged 50 to 80 years. Mortality from esophageal cancer was significantly higher in men (91.2%) compared to women. Conclusions. The consistency of morbidity and mortality levels of esophageal cancer among the population of Ukraine during 2014-2019 has been established with insignificant regional disparities. Рак стравоходу асоційований з низьким показником п'ятирічного виживання, що становить від 15 до 25% [2,3]. Подібний розвиток подій є наслідком несвоєчасного виявлення злоякісних уражень стравоходу, оскільки на ранніх стадіях вони ніяк себе не виявляють чи мають неспецифічні диспепсичні симптоми. Це зумовлено анатомічними особливостями органа, зокрема його здатністю до розтягування. Через те пацієнти звертаються до лікаря лише за значного місцевого поширення злоякісного процесу. Вважають, що в середньому тривалість анамнезу хвороби від початку виявів до моменту звернення за медичною допомогою, становить від 2 до 4 місяців.

МАТЕРІАЛИ ТА МЕТОДИ ДОСЛІДЖЕННЯ
У роботі здійснено вивчення статистичних показників раку стравоходу за період 2014-2019 рр. по Україні загалом та по адміністративних територіях на 100 тис. дорослого населення за методологією системного підходу та структурно-логічного аналізу. Опрацьовані загальні та стандартизовані за віковою ознакою та статтю показники захворюваності та смертності від раку стравоходу. Для виявлення Esophageal cancer is associated with a low five-year survival rate of 15 to 25% [2,3]. This development results from untimely detection of malignant lesions of the esophagus, because they do not manifest themselves at the early stages or they have nonspecific dyspeptic symptoms. This is due to the anatomical features of the body and its ability to stretch in particular. Therefore, patients seek medical attention only if there is a significant local spread of the malignant process. It is believed that the average duration of medical history from the beginning of manifestations to seeking medical help is from 2 to 4 months.
There are a number of studies suggesting that the survival of patients can reach 80% if esophageal cancer is detected at the early stages [4,5]. At the same time, the value of the time of diagnosis has an ambiguous interpretation. There is no established link between a shortertime to verification and the successful outcome of treatment for such malignancies. Thus, a retrospective cohort study of 3613 patients with symptoms of esophageal cancer has shown that a longer time before diagnosis was not associated with the criteria of the possibility to remove the tumor completely (odds ratio 0.997, 95%; confidence interval (СI) 0.994-1.001) and five-year overall survival (hazard ratio (HR) 0.999, 95%; CI 0.997-1.001) or fiveyear survival without signs of disease (HR 0.999; 95% CI 0.998-1.001) [6].
Epidemiology of esophageal cancer is determined by geographical distribution according to histological forms. There are two main histological types of esophageal cancer. Esophageal adenocarcinoma is more common in Western countries while squamous cell carcinoma of the esophagus is more common in Eastern populations. It is believed that this may be due to various etiological factors and genetic determinants [7,8]. However, it is accepted that regardless of the histological type, esophageal cancer has ineffective screening. It is usually diagnosed at a late stage and it belongs to one of the most aggressive malignant neoplasms in humans having an unfavorable treatment outcome. Therefore, it is important to determine the national characteristics of the epidemiological profile of this pathology in terms of understanding possible ways to improve providing medical care for this category of cancer patients.
Purpose -Studying the general patterns of time course of esophageal cancer epidemiological status in terms of morbidity and mortality among the adult population of Ukraine within the period from 2014 to 2019.
has been calculated to identify the nature of changes to determine the general trend.
The study was carried out based on the data of National Cancer Registry of Ukraine. The database of the Registry contains information on patients with malignant neoplasms detected in Ukraine. Systematized information is published annually in the form of the electronic bulletin "Cancer in Ukraine. Morbidity, mortality, indicators of the oncology service" [9]. The data from National Cancer Registry of Ukraine fully meet modern international requirements for the oncology service [10].
Statistical processing of the obtained data was performed using a Microsoft Excel spreadsheet editor and generally accepted statistical methods.

RESULTS AND DISCUSSION
According to the results of the analysis, it was found that for the period of 2014-2019, the all-Ukrainian incidence of esophageal cancer ranged from a minimum of 4.2 to a maximum of 4.9, averaging 4.5 per 100 thousand population ( Fig. 1).
When analyzing the incidence rate of esophageal cancer, it was found that in 2014 a fairly high incidence rate (higher than 6 per 100 thousand population) was observed in Zhytomyr, Cherkasy and Chernihiv regions compared to the national average. In Ivano-Frankivsk, Kherson and Chernivtsi regions, the incidence rate did not exceed 3.5 per 100 thousand population (Table 1).
In 2015, the regions with the highest incidence rate included Sumy and Chernihiv regions, while the lowest incident rate was in Odessa and Zaporizhzhya regions. A high number of cases of esophageal cancer in 2016 was observed in Zhytomyr, Kyiv and Chernihiv regions, where the rate was 5.6 per 100 thousand population, while low incidence rate was observed in Chernivtsi region (the rate did not exceed 3 per 100 thousand population).
Динамічний аналіз показав, що у 2015 та 2019 роках мало місце зменшення захворюваності як у Дніпро-In 2018, a high incidence rate of esophageal cancer was recorded in five regions of Ukraine. Thus, this indicator was 7.3 per 100 thousand population in Zhytomyr Region, 6.9 -in Khmelnytsky Region, 6.8 -in Chernihiv Region, 6.4 -in Sumy and Vinnytsia regions -6.2 per 100 thousand population. At the same time, the number of newly detected cases did not exceed 4 per 100 thousand population in Odesa and Chernivtsi regions.
In 2019, none of the regions of Ukraine had the incidence rate higher than 6 per 100 thousand population. The highest rates were found in Ternopil, Zhytomyr and Khmelnytsky regions. The incidence rate continued to be low in Chernivtsi and Odesa regions, 2.7 and 3.3 per 100,000 population, respectively.
The incidence rate of esophageal cancer in Dnipropetrovsk region in 2019 remained at the level of 2014 and accounted for 4.1 per 100 thousand population, while in Ukraine this figure decreased by 6.5%. At the same time, during 2014-2017, the number of recorded cases in Dnipropetrovsk region was 11-14% less than in Ukraine.
The dynamic analysis showed that in 2015 and 2019 there was a decrease in morbidity both in Dnipropetrovsk region (respectively, by 12 had slight fluctuations, but in general it decreased by 8.3% (Fig. 1) within six years.
In 2018, 1 745 cases of esophageal cancer were detected, 88% of which were diagnosed in men (1 536) and only 12% in women (209). The vast majority of cancer patients were aged from 50 to 80 years (Fig. 3).
Mortality from esophageal cancer is much higher in men -91.2% (1164 cases out of 1276) compared to women (Fig. 4).
A special attention among cancer forms should be paid to esophageal cancer. This localization of malignant tumors does not occupy a leading place in the structure of cancer morbidity and mortality. At the same time, the dynamics of standardized indicators of morbidity and mortality in Ukraine, taking into account the relevant forecasts, indicates a consistently difficult situation that has not been changing in recent years.
In general, the data obtained match the main trends characterizing the features of esophageal cancer. In particular, the rates of morbidity, mortality, gender and age distribution fully correspond to such rates of the burden assessment of esophageal cancer in Europe [12]. A significant contribution to cancer incidence is made by the increase among the population of Ukraine of older age groups, the risk of which is 5-7 times higher than that among younger people. Male cancer mortality is steadily 2-2.5 times higher than female.
Therefore, an urgent need to review strategies to identify patients with early esophageal cancer does exist. Cavitary surgeries can often lead to the disability of such patients. Modern endoscopic techniques make it possible