Why are Chinese people more and more likely to get cancer?

In the past decade or so, cancer has been like an evil spirit that suddenly jumped out of Pandora's box and has begun to wreak havoc around people.

"Last year, our hospital had more than 700,000 outpatient visits. When I came here in 2008, it was only 200,000 or 300,000. The number has increased by nearly 100,000 each year," Dai Min, deputy director of the National Cancer Registry Center (hereinafter referred to as the "center"), told our reporter, "It's incredible."

The "2015 Cancer Registry Annual Report" released by the center shows that in 2011, there were approximately 3.37 million new cancer cases in China, equivalent to 6 people getting cancer every minute. As is customary, the data in the 2015 annual report is a trend analysis based on data from 2000 to 2011. The latest figures provided to this magazine by the center show that in 2015, the national cancer incidence rate was 4.292 million cases, of which lung cancer incidence rate was 733,300 cases, ranking first.

"Before 2000, we discussed more about infectious diseases, and chronic diseases only started to be talked about more after 2000," Dai Min predicts that the incidence of cancer will continue to rise in the next 10 to 20 years.

Poor cancer, rich cancer

Figures provided by the center show that genetics contributes less than 20% to cancer, with the remaining 80% or more due to factors such as lifestyle. The World Health Organization believes that more than 40% of cancers are controllable.

The center's figures come from more than 300 cancer registries across the country. These registration points are located in rural and urban areas, the former at the county level and the latter at the district level. They collect tumor information according to standardized processes and methods and can cover 10%-20% of the population.

The collected figures are also among the highest in the world.

The World Health Organization previously released a research report stating that in 2012, China accounted for almost half of the world's cases, ranking first, and predicted that the number of new cancer cases in the world will increase by nearly half by 2035.

In Dai Min's view, the high incidence of cancer worldwide is related to the increasing aging population, and China is obviously not immune.

Indian-American doctor Siddhartha? In "The Emperor of All Maladies: A Biography of Cancer", Mukherjee pointed out that the reason why cancer is absent from history is first of all because it is an age-related disease, and its incidence increases exponentially with age. For example, the probability of developing breast cancer in women around 30 years old is 1/400; and among women around 70 years old, 1 in 9 will develop breast cancer. In ancient society, people were threatened by diseases such as tuberculosis, cholera, and smallpox for a long time, and often died before they got cancer.

Cancer is considered by scientists to be a modern disease, a "typical 20th century affliction" and an "excessive" metamorphosis. It invades tissues, establishes a territory in a hostile environment, seeks "sanctuary" in one organ, and then moves to other organs. It fights madly for survival, fights for every inch of land, and has a sense of defense. If people are seeking immortality, then cancer cells are also seeking immortality.

In China, as living standards have improved, the spectrum of cancer has also changed.

In the 1970s and 1980s, digestive tract cancer was the main cancer in China, also known as "poor cancer". After 2000, China began to move closer to developed countries, with lung cancer, breast cancer, and colorectal cancer increasing rapidly. Up to now, lung cancer ranks first in incidence and mortality among men, while breast cancer ranks first in incidence among women, which is basically consistent with the global trend. If divided by urban and rural areas, the total incidence rate in urban areas in 2015 was 320,000 higher than that in rural areas.

Obviously, this figure supports the statement that "cancer is related to improved living standards." "Cancer-related factors are more concentrated in cities, such as there are many fat people, many people with great pressure in life, many people who get rich quickly, and the aging level is relatively high," Dai Min told the reporter of this magazine, but if we compare the mortality rate, the rural area is higher than the urban area. After all, effective and standardized treatments for tumors are still relatively poor in rural areas.

An unhealthy lifestyle is still recognized as one of the causes of the high incidence of cancer.

Figures provided by the center show that genetics contributes less than 20% to cancer, with the remaining 80% or more due to factors such as lifestyle. The World Health Organization believes that more than 40% of cancers are controllable. Looking at the attributable hazard ratios of the major risk factors for cancer in China, viral infection, smoking, low fruit intake, drinking, low vegetable intake, and occupation are all on the list. For example, smoking. More than 30% of tumors are caused by smoking. Specifically for lung cancer, 70 to 80 percent is related to smoking.

There is no authoritative data from the government regarding the distribution and types of cancer in each province.

"The standards in different regions are different. For example, Beijing has done a better job, covering the entire population, but Hebei may only have data from a few points, which is not so comparable," Dai Min said. Only after the latest version of the cancer map is released can a clear comparison be made. "We need to adjust the data from various regions to the same level for comparison, and the situation of each type of cancer will be very clear. The source data comes from us, but we also need the cooperation of institutions such as the Chinese Academy of Sciences, and the workload is very large."

Does the environment cause cancer?

“The Ministry of Environmental Protection has environmental data, and we have disease data, but the cooperation mechanism between the two departments is almost non-existent in China.”

In Erliban Village, Xiadian Town, Langfang City, Hebei Province, 43 kilometers away from Beijing, villager Feng Jun has been working to address water pollution for ten years.

15 years ago, Feng Jun contracted a fish pond. Almost at the same time, a steel rolling mill was built. The factory's sewage discharge pipe is only thirty or forty meters away from his family's well. In 2006, Feng Jun's eldest daughter was diagnosed with acute leukemia. In June of the following year, the eldest daughter died of illness.

Feng Jun attributed it to the pollution caused by the discharge of wastewater containing arsenic and manganese from the steel mill. In the ten years that followed, he continued to petition, seek help from various media, and even conducted door-to-door investigations. He compiled a list of more than 30 people who had died of cancer in the past decade. In his opinion, this should be called a "cancer village".

In the past decade or so, the words "cancer village" have frequently appeared in the media, and some people have summarized the top ten "cancer villages" in China.

Among the public, investigations and research on "whether the environment causes cancer" are quietly underway. Yang Gonghuan, professor at the Institute of Basic Medicine, Chinese Academy of Medical Sciences and former deputy director of the Chinese Center for Disease Control and Prevention, and her team spent eight years completing the "Atlas of Water Environment and Digestive Tract Cancer Mortality in the Huaihe River Basin."

Taking the Shaying River, a first-level tributary of the Huaihe River, which flows through Chenqiu County, Henan Province, as an example, from 2004 to 2006, researchers found that the local child (malignant) tumor mortality rate was 188.81/100,000, while the national average during the same period was around 120/100,000. Before the reform and opening up, Shenqiu County was a typical agricultural county without pollution, and its cancer mortality rate was lower than the national average.

At every survey point along the river basin, Yang Gonghuan and his colleagues not only collected data on local residents' diet, drinking water, smoking, cancer incidence and mortality, but also found surrounding areas far away from the river where farmland irrigation and drinking water did not come from the Huaihe River for comparison. The same number of people track and monitor the same indicators.

Taking Shenqiu County as an example, after comparing the data over three years, the prevalence of digestive tract tumors (such as esophageal cancer and gastric cancer) in the study area was 5 times that in the control area among two groups of people with similar eating, smoking and drinking habits.

Yang Gonghuan believes that this comparison makes the pathogenic factors of water pollution clearly emerge.

Her research can be seen as the most authoritative academic explanation of "cancer village" at present. Even in the "Twelfth Five-Year Plan for Chemical Environmental Risk Prevention and Control" released by the Ministry of Environmental Protection in February 2013, the existence of "cancer villages" was acknowledged for the first time. However, this description has never been found in the annual reports of the National Cancer Registry.

Dai Min is particularly cautious about the term "cancer village". "We generally avoid it. From the existing data, there is a lack of data on the relationship between cancer incidence and the environment," she said, adding that this requires a lot of data support, especially in a large country like China. To reach such a conclusion, a large sample size is required. "So I dare not speculate on the extent of the correlation, but I cannot deny it, because there is a mechanism for risk factors."

The reason why a large number of forward-looking studies are difficult to carry out is that the Ministry of Environmental Protection and the Ministry of Health have not established a cooperation mechanism.

“As far as we know, the Ministry of Environmental Protection has relatively little monitoring of these data, and some of its subordinate departments may not all have open data. They have environmental protection data, and we have disease data, but the cooperation mechanism between the two departments is almost non-existent in China,” a relevant person told the magazine. “We just saw a cluster of cases in one place. But whether it is related to environmental pollution is unclear.”

As for the relationship between smog and cancer, which is of general concern to people, Dai Min clearly believes that at least the current high incidence of tumors has nothing to do with smog. "Tumors do not grow in three to five years, especially lung cancer, which takes at least ten to twenty years. The smog in Beijing has only become more serious since 2008. If the incidence rate has suddenly increased in the next five to ten years, it must be related to the smog."