Cancer is the second-leading cause of death worldwide and imposes a significant burden on the public health system and the economic system (1–4). The rapid increase in cancer incidence and mortality worldwide is not only related to an aging population and the increase in population size but also reflects changes in the prevalence of the main risk factors for cancer and their distribution (of the main risk factors). This study focused on two factors: age and sex. China has a large population, and cancer mortality rates are relatively high in China (5, 6). Cancer-related deaths could increase by 207,101 from 2020 to 2022 (6, 7). Inner Mongolia has a large east-west span (183,000 km²), accounting for about one-third of the total area of the country. Inner Mongolia is adjacent to Mongolia and Russia and consists of plateaus, mountains, hills, plains, deserts, rivers, lakes, and other landscapes. It has a temperate continental climate. Evidently, the composition of the nation is complex. However, we are uncertain if these complications affect the rate of cancer mortality in Inner Mongolia or whether its disease burden is severe. We also cannot be certain how the cancer mortality rate has changed in the last 60 years. Several studies were conducted over a large time span, some more than 60 years ago; however, they were conducted at a national level (3, 8). Furthermore, some published research estimates of mortality rates only focus on specific types of cancer in Inner Mongolia; moreover, other reported estimates of mortality only use data from a single year or even a shorter time (9–11).

The current study aimed to estimate cancer mortality, its burden, and its trend over a 60-year time span in Inner Mongolia. Some research suggests that cancer control efforts must contend with the issue of geographical disparity. This may offer cancer researchers some basic data and provide a reference for Mongolia and Russia.

In 2020, the CMR of cancer was 142.15/10⁵ in Inner Mongolia, and the ASMRW was 85.73/10⁵, which was lower than the national level (the CMR of cancer was 207.5/10⁵, and the ASMRW was 129.4/10⁵). The ASMRW was lower than that of the United States (86.30/10⁵) and the United Kingdom (100.50/10⁵), and significantly lower than other domestic Chinese provinces, such as Qinghai Province, the Ningxia Autonomous Region, and Shanxi Province (20–22). The top 10 cancer-related deaths in Inner Mongolia were related to the lungs, liver, stomach, esophagus, colorectal region, pancreas, breast, bone marrow (leukemia), lip, oral cavity, pharynx, lymphoma, and multiple myeloma. This accounts for 82.22% of all causes of death. Regardless of sex, lung cancer is the most reported cancer. Cancers from the first to seventh place ranking were consistent with the national ranking in 2020. The least three most common cancers reported differed from what was reported in China, namely brain cancer, central nervous system cancer, and leukemia and cervix/uterus in China (23). In Inner Mongolia, the ASMRW of the top 10 cancers was all lower than that in China. It might be associated with increased public awareness of cancer prevention following governmental efforts to educate the public about cancer education (24).

In 2020, the cancer rates among male residents (CMR and ASMRW were 179.17/10⁵ and 113.56/10⁵, respectively) were lower than the national level (CMR and ASMRW were 245.3/10⁵ and 163.9/10⁵, respectively). In 2020, the cancer rates among female residents (CMR and ASMRW were 103.20/10⁵ and 59.33/10⁵, respectively) were still lower than the national level (CMR and ASMRW were 167.7/10⁵ and 98.1/10⁵). The CMR, ASMRC, ASMRW, PYLL, and PYLL‰ rates of cancer in Inner Mongolia residents were higher in men than in women during the four reported periods, which is consistent with national findings (25). Global Cancer Statistics 2020 showed that the male cancer death rate is 43% higher than that of women (5). The ASMRW in our study was approximately twice as high in men as in women. Other published research is also consistent with our findings (26). The sex differences in cancer mortality may be caused by different working environments exposed to different carcinogenic factors, and of course, some scholars believe that different hormone levels affect the metabolism of carcinogens and thus lead to the occurrence of cancer (27).

This study found that the top five cancers causing deaths in Inner Mongolia in the first time period affected the stomach, esophagus, liver, cervix/uterus, and lung; in the second time period, lung, stomach, liver, esophagus, and the colon/anus; and in the third time period, lung, stomach, liver, esophagus, and colon/anus cancer. The top five cancer-related causes of death account for approximately 70% of all cancer deaths. From the second time period up to 2020, the top three cancers reported were lung cancer, liver cancer, and stomach cancer. We speculate that these three types of cancer may remain the main forms of cancer that contribute to death among Inner Mongolian residents in the future, which is consistent with the national data in Zongchao’s interpretation of the report (6). Lung cancer rose from fifth place in the first time period to first place in the second time period. It subsequently maintained first place in the third time period and until 2020. Moreover, the proportion and CMR increased during the four periods, but the ASMRW still increased except in 2020. From the first to the second time period, lung cancer mortality varied the most, with an ASMRW increase of 19.38%. Some studies suggested that this was due to the rapid growth of the economy, leading to industrial development and rapid urbanization, resulting in environmental degradation. Other major contributors include a high rate of smoking among residents, second-hand smoking, air pollution, and inhalation of grease smoke (from long-term cooking) (28). The fact that the ASMRW for lung cancer in 2020 is a little lower than it was in the third time period could be attributed to Inner Mongolia’s ageing population. The figures show that overall, there were 860,000 elderly individuals in the fourth census, 1.29 million in the fifth, and 1.88 million in the sixth. The average growth rate in Inner Mongolia is 47.5%, and the elderly population of Inner Mongolia is growing quickly (29). Additionally, this explains why standard cancer mortality is lower than crude mortality. Therefore, elderly people should be the target group for cancer prevention and treatment (30). Stomach, esophageal, and liver cancers were also commonly diagnosed and identified as leading causes of cancer death (3). Although stomach cancer was still one of the cancer types with a high death rate (31), its ASMRW did slowly decrease during the four periods in our study, which is consistent with the study by Cao (32). The proportion and rank of liver cancer deaths were in third place in the three national reviews on cause of death and rose up to second place in 2020; its CMR and ASMRW did however show an increasing trend from the first time period to the second time period and a decreasing trend thereafter, in 2020. The ASMRW was 15.51/10⁵, lower than that of the national ASMRW (17.20/10⁵), which is consistent with the results of many studies (33, 34). Since the first time period, the standardized mortality rate for esophageal cancer in China has decreased (35). In our study, we found that from the first to the second time period, the ASMRW of esophageal cancer was at a high level (19.10/10⁵ and 19.59/10⁵, respectively) and remained essentially unchanged, experiencing gradual fluctuations in the two subsequent time periods. In the first and second time periods, China’s medical level was limited, so it was not possible to detect esophageal cancer through screening at an early stage; therefore, once detected, it was already at an advanced stage, which led to a higher mortality rate. With the rapid economic growth and the improvement of people’s living standard, people’s awareness of cancer prevention gradually increased. From the third time period, the public are starting to pay more attention to their lifestyles, focusing heavily on maintaining a healthy weight, not smoking, and avoiding alcohol consumption. Thus, the indicator gradually decreased.

The two cancers that had a greater impact on women were breast cancer and cervical cancer. Among them, cervical cancer ranked first in deaths during the first time period in this study. The mortality of cervical cancer and death declined during three national reviews on cause of death and slightly rebounded in 2020. Most countries showed the greatest decreasing changes in breast mortality, and some countries experienced a stable trend (36, 37). It may be possible to avoid cervical cancer by identifying and treating cervical precancerous lesions. Screening and identifying cancerous lesions early may also reduce mortality. The age-standardized mortality rates of breast cancer significantly increased in China during the third time period and 2015, but decreased in the USA, Australia, and the United Kingdom (38). This study showed that the mortality rate of breast cancer decreased from the third time period to 2020, revealing an ASMRW of 6.65/10⁵ and 4.15/10⁵, respectively. During the four periods, the lowest ASMRW of the four periods was in the second time period (2.46/10⁵). The decreasing trend in the proportion of deaths from breast cancer is consistent with the findings of some other research (39, 40). Risk factors for breast cancer are linked to China’s rapid economic development, such as the “Westernized” diet (high-fat and energy density), which increased obesity rates, physical inactivity, shortened breastfeeding durations, and later ages for first pregnancies, also significantly led to the rising mortality rate of breast cancer (41). But early screening could reduce the mortality of breast cancer, especially in women aged 50 and older (42).

Mortality reflects the frequency of death in a population pertaining to a disease, and PYLL reveals the effect of age at the time of death on life expectancy. Both can organically combine the frequency of death and life expectancy loss to reflect the burden of disease death on the population and society from different aspects (43). The burden of early death caused by cancer in the region was serious (31, 44–46). In our study, the four time periods of PYLL‰ were 9.05‰, 10.79‰, 12.1‰, and 10.38‰ from 1973 to 2020. The overall crude mortality rate of cancer in Inner Mongolia during the four periods showed an increasing trend (PPC = 1.77%, P<0.05), including an increasing trend in the crude mortality rate in males (PPC = 1.86%, P<0.05) and an increasing trend in the crude mortality rate in females (PPC = 1.68%, P<0.05).

The trend of cancer mortality among Inner Mongolia residents during the four time periods was generally on the rise with age, which is consistent with the national situation (20, 47). The mortality rates of cancer increased with age in the first time period and in 2020 for ages 10 to 84. The same trend was found for ages 0 to 74 in the second and third time periods. After peaking at age 75, it began to decline. This is slightly different from the national trend but consistent with the Jiangsu study (25, 48). The mortality rates for ages 0 to 64 in 2020 are lower than the previous three reported findings. This may be related to the continuous progress of medical care and the continuous improvement of medical examinations and screening systems nowadays. Furthermore, the increase in age-specific mortality rates afterwards compared to the previous three times may be related to the cumulative delay of 10–20 years in the accumulation of carcinogenic factors such as air pollution and smoking (49).

In summary, the three cause-of-death analyses show that the PYLL‰ of cancer is gradually increasing and that the most common type of cancer that results in death is lung cancer, but there are also other common types of cancer that occur, such as those affecting the liver, stomach, esophagus, and colon. The mortality rate of cancer in Inner Mongolia is higher in males than females, and the mortality rate increases with age. To better prevent the occurrence of cancer, we should actively encourage smoking cessation, increase the screening of cervical cancer and breast cancer for women, and actively monitor the health of older people, while also focusing on the screening of adolescents and middle-aged people. To reduce the incidence and mortality of cancer, we should strengthen research on risk factors for cancer and carry out active prevention and control in a targeted manner. This will raise the quality of life for Chinese citizens.

The original contributions presented in the study are included in the article. Further inquiries can be directed to the corresponding authors.

RH and ZM: Study design and manuscript writing. WN and ZL: Review and editing. BN and WK: Data collection. All authors contributed to the article and approved the submitted version.