Zhang Zuofeng: In the past ten years, the incidence of different cancers in China has risen and fallen, how to correctly "fight cancer"?

Guide

In the past two days, the world's largest oncology conference was held in the United States, and many domestic clinicians went to communicate and share.

In order to better understand the epidemic trend of cancer in China and take corresponding measures, we recently interviewed Zhang Zuofeng, head of the Department of Epidemiology at the UCLA School of Public Health and distinguished epidemiologist Zhang Zuofeng.

Professor Zhang graduated from the School of Public Health of Shanghai Medical University, and served as a member of the National Institutes of Health Cancer Epidemiology Program Review Expert Group, and a senior member and director of the American School of Epidemiology.

Professor Zhang has always been concerned about the development of public health in China, and has done a lot of research on the causes of different cancer epidemics, and has done a lot of excellent work in cancer epidemics from the 90s of last century to the present.

Zhang Zuofeng | Guests

Ye Shui sent | interview

01

The incidence trend of cancer in China is different from that in Europe and the United States

Ye Shuishui: There are many cancer patients in China, the tumor burden is very heavy, and the patients with lung, breast and colorectal cancer have been high, what do you think of the incidence trend of cancer in China? How do these cancers differ from the epidemic in Europe and the United States?

Zhang Zuofeng: In general, the incidence of tumors in the world is rising, and the mortality rate of tumors is decreasing, but because of the huge number of Chinese, the number of tumor cases and deaths in China are the first in the world.

In the past 10 years or so, the main traditional tumors in China - esophageal, stomach, liver and lung cancers - have several basic characteristics:

First, the fatality rate is high.

Second, it has to do with the people's living standards.

Third, it is related to people's living habits, and even related to infection.

Gastric, esophageal and liver cancers are all major tumors, accounting for about 70%-80% of the total number of tumors.

In the past ten years, the incidence of lung cancer has gradually increased, but the incidence of several cancers has decreased significantly: stomach cancer, esophageal cancer, liver cancer is declining.

These three tumors are all highly lethal tumors, and their decline means that stomach cancer, esophageal cancer, and liver cancer have reduced the risk factor to human life and health. So what is the reason for the decline in the incidence of these tumors?

First, I think it is the improvement of living standards.

Stomach cancer and esophageal cancer, for example, are mainly malnutrition, and poor nutrition may cause such tumors;

The second is the problem of pollution in food and drinking water.

Third, infection. The cause of infection of stomach cancer is "Helicobacter pylori".

In China, about 60% of people have been infected with Helicobacter pylori. Helicobacter pylori is one of the most important factors causing stomach cancer, and the World Cancer Center positions it as a "grade I carcinogen". However, due to improved lifestyle habits, the incidence of these tumors has decreased.

So why is the incidence of liver cancer declining? When it comes to liver cancer, in fact, liver cancer has a lot to do with "eating". In the southeast coast and Guangxi, the incidence of liver cancer is quite high; In addition, the high incidence of liver cancer is also related to the humid climate. The humid climate makes some foods prone to aflatoxin, which can also cause liver cancer. In China, liver cancer is mainly hepatitis B, and the positive rate is about 15%.

In the late 80s and early 90s, the hepatitis B virus immunization for newborns in China also led to a decline in the incidence of liver cancer, coupled with changes in our nutrition and food storage methods, and the popularization of refrigerators, the incidence of liver cancer showed a downward trend.

The incidence of gastric cancer, esophageal cancer, and liver cancer is declining, so what tumor incidence is increasing in China?

In China, the incidence of tumors is on the rise, first of all, female breast cancer, and its rate is rising very fast. From 1988 to 2012, it rose by about 60%-70%.

The second fastest rising is colorectal cancer. Colorectal cancer is related to the improvement of our living standards, nutrition has increased, but people's physical activity is declining.

In China, the first place where colorectal cancer rises is in a place with better living conditions. For example, Zhejiang Province has always ranked first in the incidence of colorectal cancer.

The incidence of two tumors, breast cancer and colorectal cancer, is on the rise. Lung cancer, however, has been on the rise; The decline in lung cancer incidence in women was smaller, but there was no significant increase. This is similar to the trend of the world.

In the past, Chinese thought it was difficult to quit smoking, but now that health education is more sound, the proportion of Chinese quitting smoking is increasing year by year. Lung cancer in women is a big problem, and the key to this problem is that only 4% of women with lung cancer smoke, and the vast majority of women with lung cancer do not smoke.

Why do non-smoking women get lung cancer?

First, 50%-60% of men in China smoke, and many women are forced to inhale secondhand smoke.

Second, in most northern rural areas, women spend more time in the kitchen, and poor kitchen ventilation can easily cause lung cancer.

Third, outdoor air pollution. Outdoor air pollution is difficult to avoid and sometimes not at the individual level.

02

The differences in lung cancer factors in China and the United States and the similarities and differences in the incidence of different races

Ye Shuihui: Lung cancer is the number one cancer in China and the number one cancer in the United States. Are there any differences in the factors that develop lung cancer between the two major countries? In addition, are there any similarities and differences in the causes of morbidity between different races?

Zhang Zuofeng: In China and the United States, lung cancer is a tumor with a high incidence of cancer.

First, smoking and secondhand smoke.

About 80%-90% of lung cancers are caused by smoking, and some lung cancer patients are caused by passive smoking.

Second, air pollution.

In the United States, some basements will be contaminated with radioactive material. Occupational exposure at work may also cause lung cancer.

In terms of outdoor pollution, China is more polluted than the United States. In terms of indoor pollution, the smoking rate of men and women in the United States is about 20%, and the passive smoking rate is relatively low; However, the smoking rate of Chinese men can reach up to 70%, and it is currently about 50%, which will cause women to smoke passively.

Third, the difference in cooking.

Americans cook with less probability of oil smoke pollution, which is because Americans cook mainly roasted and cooked, and Chinese like to heat the oil pot, which will appear light smoke, smoke itself is a carcinogen.

Fourth, genetic causes.

In terms of genes, different disease-causing genes for lung cancer in different races have not been found, but genes play a role in the process of lung cancer causing cancer, especially in nicotine receptor genes.

The increase in the proportion of lung cancer in Chinese women is actually mainly due to the increase in adenocarcinoma, which is related to genes. But there is also good news, and there are treatments that specifically target these genes.

03

The relationship between aging and cancer

Ye Shuihui: At present, the aging of the world, including China, is intensifying, what do you think of the relationship between aging and cancer? Does increasing ageing also mean an increase in the number of cancer patients?

Zhang Zuofeng: In addition to children's tumors, most tumors are closely related to aging. In foreign countries, many tumor patients are generally over 60 years old, and adult tumors are related to age.

First, as we age, the cumulative dose of exposure is relatively greater.

For example, young people smoke a pack of cigarettes a day, and smoking for 10 years is exposure for 10 years; Older people smoke for 30 years, that is, exposure for 30 years, and age itself is a variable of "exposure", which also increases the risk of tumors.

Second, the immunity of the elderly after illness is also declining, and many physiological mechanisms in the body may cause tumors. For example, the level of hormones produced in the body, the level of immunity in the body, including many changes in the body and metabolic changes, have contributed to the increase of some tumors.

04

The impact of the pandemic on cancer patients around the world, including in China and the United States

Ye Shuishui: The epidemic has gradually faded around the world, which has made us refocus our attention on the cancer patient group. How do you see the impact of the pandemic on cancer patients around the world, including in China and the United States?

Zhang Zuofeng: The epidemic has had a considerable impact on cancer, which is the same situation all over the world.

The first is the impact on cancer treatment.

Many cancer patients cannot enter the hospital and cannot be properly treated because of the epidemic, and many cancer patients eventually die.

In the United States, too, doctors can't see patients, perform surgery, get into hospitals, or prescribe medication. As a result, the 5-year survival rate for cancer is greatly reduced.

We generally say that "1/3 can be prevented, 1/3 can be detected early, and the remaining 1/3 can be treated". The pandemic has caused the "1/3 of the treatable" segment of people to leave us prematurely.

Second, early screening for cancer is not possible.

The goal of early screening is to detect early cancer symptoms. Generally speaking, the survival rate of early cancer and advanced cancer after timely treatment is completely different.

For a simple example, the five-year survival rate of early breast cancer (stage 0 or Ia) can reach more than 90%, and after proper surgery and treatment, its fatality rate will not be so high.

Another successful example in China is cervical cancer screening. In the past, cervical cancer screening could be done as a cervical smear, but now with HPV screening, these means can detect early pathology earlier. Cervical cancer is characterized by the fact that not only early pathologies can be found, but also precancerous pathologies. After the detection of precancerous pathology, it can be treated early, and it is basically unlikely to develop into invasive tumors after that.

But due to the pandemic, large-scale, small-scale, clinical cancer screening has largely stopped.

Third, during the epidemic, many people's living habits have changed greatly.

Not only lifestyle habits, but also other influences.

As a simple example, people who smoke, whether they smoke, are locked up in their homes and are much more likely to smoke, as is drinking.

Abroad, people locked up in their homes can also use some illegal drugs. Locking up at home also means not being able to go out to do physical exercise, and not getting enough physical activity can also cause some tumor risk factors to change.

There is also diet, locked up at home, we may not be able to do a balanced diet, may eat some unhealthy foods, which will also have an impact.

In addition, the epidemic is locked down at home, which may cause some stress and depression, which are related to cancer. So the epidemic has a considerable impact on cancer, and it is quite far-reaching.

05

Recommendations for reducing cancer

Ye Shuishui: What advice do you have for reducing the incidence of cancer? How can the rapid increase in the number of cancer patients be curbed?

Zhang Zuofeng: First, quit smoking. For lung cancer, I think it's better for smokers to quit smoking. The good news is that as long as you quit smoking early, the probability of getting cancer will decrease. Smoking does not only cause lung cancer, it can cause 16 different tumors, including oral cancer, laryngeal cancer, pharyngeal cancer, esophageal cancer, pancreatic cancer, stomach cancer, liver cancer, kidney cancer, bladder cancer, leukemia.

The probability of smoking causing cancer is high, so it is best for people who do not smoke to never start, and people who already smoke are better to quit as soon as possible.

Smoking can also cause heart disease, stroke, diabetes, and comprehensive obstructive syndrome of the lungs, which is what we used to call "old and slow branches".

Is smoking related to breast cancer and colorectal cancer? The relationship with breast cancer is still controversial, but smoking and colorectal cancer are still related.

Second, reduce indoor air pollution. Try to minimize the habit of frying, frying, or cooking too hot with fumes. When cooking, you can pour some oil, put some water after pouring the dish in, and cover the pot, which is relatively healthy.

Third, a reasonable diet. The rationality of diet is very important, and diet has a lot to do with breast cancer and colorectal cancer. The so-called reasonable diet is "the amount of fat decreases, the amount of protein increases, the amount of fiber increases, and the amount of sugar decreases."

As a simple example, an increase in fiber can cause unobstructed stools. Many colorectal cancer patients have symptoms of constipation. Feces in the large intestine itself has some chemicals that can cause cancer, so increased bowel motility can reduce the incidence of cancer.

In addition, fat should not be high, and high fat will also have a great impact on cancer. But so far, we have not made a concluding conclusion about fat, we can conclude that "fat must cause cancer", and reducing fat is definitely beneficial to people. After increasing fat, you will also gain weight, and obesity will also cause tumors, so adjust your diet to "low sugar, high fiber, high protein, low fat".

Why are there so many diabetics in China and their blood sugar rising so fast? This has something to do with eating rice. Therefore, it is recommended that it is best to use foods such as rice and steamed buns as supplementary foods, and eat more vegetarian dishes and high-protein fish and shrimp. It is best to eat white meat (fish, shrimp, chicken), eat less red meat (pork, beef, lamb), increase protein intake, and reduce the incidence of cancer through a reasonable diet.

Fourth, avoid excessive alcohol consumption. Alcohol can cause many tumors, like breast cancer and rectal cancer.

When I was participating in the World Health Organization's expert group on alcohol consumption and cancer, I was able to identify a strong correlation between breast cancer, colorectal cancer and alcohol consumption at the symposium.

So far, including red wine, any kind of wine is a major cause of cancer. The more you drink, the more danger increases. So it's best not to drink, and if you really want to drink, try to limit it to a small glass of red wine a day.

Fifth, pay attention to physical activity. If you do a lot of physical activity every day, you don't need to exercise. But now there are many white-collar workers sitting in the office, sitting in front of the computer for eight hours without much movement, and eating, drinking, and sleeping after work, such a routine is actually detrimental to people.

It's best to make sure we have more than forty minutes a day for physical activity. Swimming, walking, running, playing basketball, these are all good exercises, if you are older, you can choose to jog or walk.

Finally, it is to maintain mental happiness, mental health is very important, and optimism is also a good medicine for diseases.