Can children get lung cancer
It has been pointed out that children can get lung cancer, and some news reports or literature reports have been provided as well. News reports cannot be used as arguments in scientific discussions, so I will leave it at that. I have read all the research papers that people have sent me on lung cancer in children and the results are interesting and arguably disprove my conclusions while supporting some of my points.
First, it is possible for children to get lung cancer, and I apologize to everyone for my mistake on that point. However, after reading the few research papers on lung cancer in children, I realized that there are reasons for my mistake.
1. Childhood lung cancer is extremely rare, and there are only a few in the world in a year.
I have studied cancer biology for more than 10 years and attended numerous academic conferences, and I have never heard of pediatric lung cancer. A large 250-bed children’s hospital in South Africa has admitted a total of 4 pediatric primary lung cancer patients in 31 years. The 639-bed Texas Children’s Hospital in the United States had only 14 pediatric primary lung cancer patients in the 25 years from 1982 to 2007.
2. Childhood lung cancer is significantly different from adult lung cancer and is not a disease at all.
Most of the so-called childhood lung cancer cases sent to me by many readers are metastatic lung cancer (other childhood cancers such as brain, nerve and muscle tumors metastasized to the lungs).
What would be associated with air pollution would be primary lung cancer (cancer that emerges directly from the lungs), which has an extremely low probability within children, and it is distinctly different from lung cancer in adults. The most common types of lung cancer in adults are adenocarcinoma of the lung and squamous lung cancer, of which squamous lung cancer is directly related to smoking, and the majority of patients with squamous lung cancer smoke, which is the type of lung cancer that should be most directly related to air pollution.
However, in the literature that I have read, I have not seen a single case of childhood squamous lung cancer. Instead, among childhood lung cancers are pleuropneumoblastoma, pulmonary carcinoid tumors, and other extremely rare cancer types. These lung cancers, like other childhood cancers, are clearly associated with congenital developmental and genetic defects rather than being the product of environmental pollution.
Therefore, from the literature read so far, the accurate statement is that it is possible to get lung cancer in children, but unlike adult lung cancer, it is primarily a congenital factor and there is no evidence of any association with environmental pollution.
Note that this is not to say that haze has no effect on children, nor is it to say that long-term haze does not increase the chances of children getting lung cancer as adults. These two questions fall under a separate issue to be addressed below: Can haze cause lung cancer?
Haze and lung cancer: why can’t scientists agree?
The relationship between haze and cancer is hotly debated, this time not only by the public and scientists, but also within scientists are split into different camps, some support that haze causes cancer, others think they should be more cautious. For example, the recent debate between academician Zhong Nanshan and Fang Zhouzi is very representative.
Scientists arguing about the relationship between haze and cancer in China are mainly debating whether there is scientific “direct evidence” to strictly prove that haze causes cancer. Contrary to what we all suspect, there are not many reliable research papers on the topic of “haze causes cancer”. Because epidemiological studies on lung cancer caused by air pollution are difficult to do and the evidence is not good.
1. It is impossible to find a perfect control group for this study.
To study the effect of a new drug on patients, there must be a control group, otherwise it is meaningless. Similarly, to study the effect of haze on cancer, there must be a control group. We should compare whether there is a difference in the probability of getting lung cancer in the same group of people, with or without haze.
Theoretically, the perfect experiment to obtain “direct evidence” of Chinese haze causing cancer would be like this: In a parallel universe, there are another 1.3 billion Chinese people who are just as hard-working, kind, loving, and dedicated to the Party as we are, but just don’t pollute the air, so let’s compare them with the 1.3 billion Chinese people in our universe. Let’s compare them with the 1.3 billion Chinese in our universe and see if there is a difference in the incidence of lung cancer. The only difference is that one group is inhaling the air of Beijing during the two sessions, and the other group is inhaling the air of Beijing after the two sessions are over when the PM2.5 is exploding.
But this is obviously science fiction, and a perfect experiment is impossible. So can we step back and compare two groups of people who are similar? For example, can we compare the incidence of lung cancer in China before pollution occurred (before 1950) and after severe pollution (after 2000)? Isn’t it popular on the internet to say that we have tens of times more lung cancer incidence now than we did decades ago, suggesting that environmental pollution is the main cause! But there are many problems inside this data. First of all, before industrial pollution occurred in China, the medical level was also very backward, and many lung cancer patients died in rural areas without knowing what the cause was, so the number of lung cancer patients before must be seriously underestimated and cannot be directly compared. If we find that there are many more lung cancer patients now than in 1950, perhaps it is simply because more have been diagnosed and registered.
In addition, the average life expectancy in China has been increasing due to improved health care, and aging is the number one contributor to cancer, so it is not at all surprising that the incidence of lung cancer has increased. So, the statement that lung cancer in China has increased dozens of times more than before because of environmental pollution or something like that is actually simplified and exaggerated because of these two reasons.
Can you compare countries with different levels of pollution in the same period? How about comparing the United States and China now, for example? This is also problematic, because there are very many differences between countries, regions, in addition to different air pollution. In the United States and China, for example, there are different ethnic compositions, different average life expectancies, different numbers of smokers, different levels of tobacco control in public places, different water pollution, different diets, different obese populations, and so on.
All of these factors can affect the incidence of lung cancer, and it is scientifically very difficult to eliminate all of these factors and to quantitatively compare the effect of air pollution on lung cancer. Even assuming you find that lung cancer rates are lower in the United States than in China, it is possible that this is because there are fewer people smoking in public in the United States and less secondhand smoke pollution, and it has nothing to do with air pollution such as haze. (In fact, the US, Canada, Denmark and several other developed countries with clean air have higher lung cancer rates than China)
2. “Now it is proved that Chinese haze causes cancer” itself is a false proposition.
The effect of haze or any environmental pollution on cancer must be chronic and long-term, and it is impossible to have immediate effect. For example, after the United States dropped the atomic bomb on Hiroshima and Nagasaki, Japan during World War II, a large number of surviving residents were severely exposed to nuclear radiation, which is a cancer-causing factor many times more serious than haze. But note that even for a cancer-causing factor as strong as nuclear radiation, the concentrated outbreak of leukemia in victims came 5 years after the radiation exposure, and the outbreak of other cancer types came 10 years later! Therefore, to study the effect of haze or other pollution on the incidence of lung cancer or other cancers in China now, we have to wait until 10-20 years later to draw conclusions.
Therefore, no matter what kind of data is produced now, scientifically, it is impossible to “directly prove” that the current haze causes cancer. If the increase in lung cancer in China in recent years is thought to be caused by environmental factors, it should be traced back 10 to 20 years to see what other kinds of environmental pollution occurred in China at that time. We do not have “direct evidence” that the current haze causes cancer, because this evidence exists in the future and has not yet appeared.
For these two reasons, the scientific community cannot strictly prove that the haze that now hangs over China can cause lung cancer.
Does haze cause lung cancer: intuition and science both say it does
As you can see, the reason why the relationship between haze and lung cancer has not been nailed down is purely due to the limitations of epidemiological research methods. This does not mean that we cannot scientifically analyze whether haze can cause cancer. I’ll start with my opinion: haze is definitely pathogenic and carcinogenic, it is necessary to keep children away from the ravages of haze, it is tragic that Chinese people are collectively forced to “share the same whistle, share the same fate”.
Why do I think the haze causes cancer? At the end of 2013, the World Health Organization (WHO) came to the conclusion that “air pollution causes cancer” after collating more than 1,000 relevant research reports from around the world, and also clearly put Airborne particulate matter (including PM2.5) is classified as a Class I carcinogen.
Carcinogenic substances are classified into 4 levels according to their severity, namely Level 1 “definite carcinogen”, Level 2 “probable carcinogen”, Level 3 “undetermined carcinogen”, Level 4 “Unlikely carcinogen”. The classification of haze (PM2.5) as a Class I carcinogen is equivalent to saying that the World Health Organization believes that there is sufficient evidence of a direct causal relationship between air pollution and cancer (lung cancer). Other common carcinogens listed as Class I include tobacco, acetaldehyde (alcohol consumption), hepatitis B virus, and pickled salted fish (Chinese style).
I was also drunk to see the World Health Organization put brackets after salted fish (Chinese-style). Meanwhile, the World Health Organization published a book stating that in 2010, about 3.2 million people died worldwide because of air pollution, mostly from cardiovascular diseases, of which 220,000 were expected to die from lung cancer, and more than half of the lung cancer deaths were in China and other Asian countries. Therefore, the conclusion that haze can cause disease and cancer is commonly accepted by a large number of experts from the World Health Organization.
As I explained earlier, some would argue that much of the WHO evidence is indirect and there is too little direct evidence. But even without the WHO report, I am a clear supporter of the theory that haze causes cancer (lung cancer). There are two big reasons for this scientifically.
1. Haze contains cancer-causing chemicals. The composition of haze, or PM2.5, is very complex and varies from place to place, but all include hundreds and thousands of various physical and chemical substances. Some of these are clearly linked to cancer, such as sulfur dioxide and nitrogen oxides. Long-term inhalation of large amounts of such compounds may lead to genetic mutations and increase the chance of lung cancer.
2. The fine particles in the haze can cause long-term chronic lung damage and accelerate lung aging. In my previous article “What causes cancer? I said that the root cause of cancer is genetic mutation. Excluding congenital genetic factors, the probability of genetic mutations occurring is directly related to the number of cell divisions. Every time a cell divides, there is a certain probability that a mutation will occur, so the more times a cell divides, the greater the chance of getting cancer, which is why it is mainly older people who get cancer. The longer you survive, the more times your cells need to divide, and the higher the chance of getting cancer according to the probability.
Under heavy air pollution, various physical particles and chemicals inhaled can cause cell damage in the lungs, even if the direct carcinogens in them are not considered. In order to repair this damage, the lung cells then need to divide and proliferate more. Therefore, long-term air pollution will cause repeated “damage-repair-damage-repair” cycles in the lungs, leading to massive cell division and thus increasing the probability of lung cancer. Simply put, air pollution will lead to accelerated lung aging, and lung cancer is one of the most dangerous consequences of lung aging.
The more haze particles inhaled, the greater the harm to the body, children are outdoors, no sense of protection, deeper and more frequent whistling, so they are certainly the biggest victims of the population, although I do not agree to keep children at home all the time, but certainly will not let children run in the haze “naked” for a long time. Similarly, adults do not do protection in the haze for long-distance running, square dancing and other strenuous exercise, is also taking life in fitness, is definitely “true love”.
More horrible things than haze
Haze must be treated, but if only from healthy life and avoid cancer, eliminating haze is far from enough, because haze is far from the main factor that causes cancer. According to a recent large-scale study, outdoor air pollution does not rank in the top 5 of factors that cause cancer, more serious than it are: smoking (far ahead), alcohol consumption, lack of fruits, obesity and lack of exercise, and similar to outdoor air pollution are long-term intake of high-salt food, indoor air pollution (such as frying fumes, renovation) and lack of vegetables.
Therefore, while everyone is pushing for government policies to change air quality, there are already many things that everyone can do to keep themselves and their families safe from cancer: quit smoking, quit drinking, eat more fruits and vegetables, exercise more, eat less high-salt and pickled foods, etc. Smoking (including secondhand smoke), in particular, is N times more likely to affect lung cancer than haze, and frankly, what good is a cure for haze when there are still large numbers of people smoking in public places?