Epidemiological and clinical characteristics of cancer in Mongolia from 2017 to 2021

Abstract

Introduction: the overall rate of cancer incidence is increasing and it remains one of the most common and lethal disease worldwide. Cancer incidence and mortality rates vary significantly around the world. Geographical differentiation is one of cancer’s most distinguishing features. Effective prevention and early detection strategies are the most critical public health interventions for various types of cancer. Notably, understanding the risk factors associated with cancer is required for identifying high-risk groups that may require screening for prevention. As a result, current statistics on cancer occurrence and outcome are critical for primary disease prevention. Cancer is the second leading cause of death globally, accounting for an estimated 9.6 million deaths, or one in six deaths, in 2018. Alterations in the environment, technology, and lifestyle have changed the pattern of diseases in Mongolia. Currently, in Mongolia, non-communicable diseases such as heart disease, obesity, liver disease, lung disease, and cancer are more dominant. According to the GLOBOCAN 2020 report, Mongolia has the world’s highest incidence and mortality rate for liver cancer at 86.5 per 100.000 population (Cancer Today (iarc.fr)). Purpose: This thesis examines the epidemiological characteristics of cancer and factors associated with new cancer cases among the Mongolian population from 2017 to 2021. Objective: To compare differences in cancer diagnosis in the Mongolian population sub-grouped by residence area, sex, and age. Methodology: A cross-sectional descriptive study was conducted using secondary data on new cancer cases registered in Mongolia from 2017 to 2021, 23,499 cancer cases were recorded. Among them, our analysis focuses on 15.439 new cases of seven most prominent cancer types in all regions of Mongolia. Our data were converted using Jamovi version 2.3.8, and descriptive statistics were performed using frequencies and percentages. Association of cancer type compared with age, sex, cancer status, and residence area was calculated by Pearson’s Chi-square analysis or Fisher’s exact test, and the factors associated with cancer type and socio-demographic characteristics of the patient were be examined by the direct method of age-standardized rate. Exposures: Residence (UB city, western, eastern, Khangai, and central-Gobi regions), sex (male and female), age (0-30, 31-45, 46-60, 61-85 and >85 years), and stage of cancer (primary, metastasis, and malignant). Results: According to the findings of this study, 41.03% of new cases from the study period were diagnosed with liver cancer, 21.22% were diagnosed with stomach cancer, 11.64% with lung cancer, and esophagus 8.73%. The remaining 6.56%, 6.49%, and 4.3% were diagnosed with breast cancer, cervical, and rectum cancer, respectively. About 85.8% of all newly diagnosed cancer patients were aged 46–85, and 53.4% were male. Approximately 51.68% were living in UB city, and 82.2% were diagnosed at the metastasis stage. The Central-Govi region had a higher incidence of 672.53 per 100,000 population. Compared to the residents of the Central-Govi region (OR: 0.62362 95%CI=0.56165-0.69241 P< .001), UB city was more likely to be associated with liver cancer than stomach cancer. Conclusion: This study’s magnitude shows that liver cancer has been most commonly diagnosed in the last five years, which is similar to Ferlay’s survey (Ferlay et al., 2013). Liver cancer is by far leading type of cancer in Mongolia, contributing almost two-fifths of the total cancer burden, the highest rate in the world. Although the highest number of cancer cases have been registered in Ulaanbaatar city, according to the age-standardized incidence rate per 100,000 population, the highest number of incidences have been registered in the Central-Govi region (673.52 / 100,000 population) followed by the second highest indicate rate of 616.38/100,000 population in UB city.