Childlessness tax
Cancer: it cannot be stopped, but it can be prevented… Only you don't want to
Alexander Berezin, Naked Science
For links, see the original article
In 2017, 9.6 million people died of cancer, and this figure will grow every year. Are there any ways to stop the onset of this disease on human lives?
Stories about new methods of fighting cancer are constantly flashing in the news. From the outside, it may seem that this is just another disease that medicine is about to defeat. In fact, it's not like that at all. Humanity will not be able to get rid of cancer at all. However, it is already known who suffers from it half as often as others. But joining this club of "cancer-resistant" will be expensive, and you will not have to pay with money at all. Let's try to figure out why this is so.
Tumor: a random gene copying error or something completely different?
To understand how to deal with the disease, it is necessary to find out what it is. It's hard to treat what you can't understand. And so with the awareness of the true causes of cancer, so far everything is not so good.
At school, they explain to us that cancer is a consequence of simple mistakes in the division of our cells. During this division, DNA molecules are copied, and for three billion "letters" some number of errors is inevitable. As a result, errors accumulate. And sooner or later, an ordinary, mortal human cell becomes immortal – in the sense that it can divide an unlimited number of times and live indefinitely for as long as it receives nutrients. Starting to divide rapidly, cancer cells literally crowd healthy ones, pain, organ malfunctions, death come.
Such a scheme for the appearance of cancer intuitively seems quite logical. But it has drawbacks: statistics both among different species and within a species of people do not support the hypothesis that cancer is the result of random mistakes, according to the principle "it happens to everyone".
If it were so, cancer would occur more often, the more cells in the body. In fact, there is nothing further from the truth. Every twentieth elephant in his life will face this disease, although elephants, like humans, live for a long time and, having reached adulthood, practically do not die from infections and predators.
In the world as a whole, one in five people will face cancer in their lifetime, and in developed countries – two out of five. At the same time, an elephant has 100 times more cells than we do. Of course, some of them may share a little slower, but not 100 times. There are even tougher examples: whales. A whale can have a thousand or even ten thousand times more cells than a human. But cancer in them is probably even rarer than in elephants.
An astute reader will say: well, why are you comparing us to elephants with whales. Obviously, they have different genes. Large animals cannot have the same probability of cancer as small ones: then they would be a hundred-thousand-ten thousand times more likely to die from tumors. That is, they simply did not live to adulthood. Clearly, evolution should have given them genetic protection.
It's true: elephants have such protection. We are talking about the TP53 gene, which is responsible for the synthesis of the p53 protein, which suppresses the development of tumors in the mammalian body. We have only one gene, elephants have 20 copies of them. In whales, the mechanisms of protection against the transformation of ordinary cells into cancer cells differ significantly, but they are no worse than elephant cells.
Another misconception is common among educated people. Supposedly, cancer is a natural process (like any mistakes), which stands at the end of the life path of any creature, if it does not die from infection or predator. Therefore, many believe that the more medicine develops, the longer a person lives, the more we will die from cancer.
This hypothesis, with external logic, does not stand up to verification by facts. Whales live up to 200 years. Adults of their large species are practically inaccessible to predators, and epidemics. If cancer were the natural end of a multicellular organism, whales would die from cancer – and at about the same time as humans. And this means that they would not be in danger of living up to 200 years at all. Alas, whales are not aware of human hypotheses, so they continue to enjoy longevity.
It is obvious from the example with elephants: nature has effective mechanisms of protection against cancer. Why doesn't she use them on smaller organisms, not just elephants and whales?
This question arises by itself, but in fact it is incorrect. Evolution has perfectly protected quite small organisms from cancer. For example, naked diggers (small rodents) to date, they have given only a couple of cases of cancer – and only one of them, in theory, could be fatal. Yes, and there we are talking about cancer obtained in unnatural conditions for this organism.
Naked digger in nature lives at great depths, where oxygen is no more than 9%, and he got cancer in a research center, with 21% oxygen in the air. If we were kept at 45% oxygen forever, instead of the usual 21% for aboveground creatures, the frequency of various diseases would also change for us.
The naked digger is much smaller than us, but almost does not have cancer. Elephants with whales are much bigger than us, but they get cancer much less often. What's the matter? Why are we humans so, how should I put it mildly, unlucky? Why does evolution seem to care about protecting our species from cancer?
What are ordinary people inferior to sectarians who force women to wash with their hands
The incidence of cancer has been growing dramatically over the past decades, and the more developed the country, the faster. But there are exceptions – and big ones. For example, there are many different sectarians living in the USA, including the Amish. Their religious views prohibit the use of cars, phones and other Internet. Even the mechanization of agriculture (they are mostly farmers) it is prohibited there (although the cultivation of GMO plants and the use of pesticides are allowed).
Well: they get cancer 40% less often than non-Amish neighbors living in the same areas of the United States. Maybe it's because the Amish don't smoke? Yes, they are 63% less likely to have cancers associated with smoking (lung, respiratory tract) than non-Amish from the same area. But the fact that it is not 100% lower shows that cancer "associated with smoking" in 37% of cases may not be associated with smoking at all.
Most importantly, non-smoking cancers are 28% less common in Amish than in ordinary people of the same age groups. Meanwhile, because the Amish are positive about vaccination and medicine in general, their life expectancy is as high as that of non-Amish Americans.
It is especially intriguing that all attempts to find at least some genes in these sectarians that give them resistance to tumors have shown zero results. In addition, their diet is unsafe from an anti–cancer point of view: a lot of fat, calories and sugar - which, as we are often told, increases the risk of tumors. Conclusion: something dramatically reduces the incidence of cancer among them. But this is something not genes, like elephants, but a way of life, and basically it's not about quitting smoking and certainly not about healthy eating.
Many believed that increased physical activity protects them from cancer. If you don't have internet, phone and TV with a car, you will inevitably walk, for example. In fact, Amish men take 18 thousand steps a day, Amish women - 14 thousand. A typical American does two or three times less per day. As a result, only one in 25 people is overweight, and among Americans in general, one in three (the average Russian is much closer to the second figure). But the problem is that cancer is less common among Amish artisans who have moved away from agriculture. And among those of them that are still overweight.
Even worse is that among athletes from among ordinary people, physical activity is higher than among Amish, and the frequency of smoking is just as vanishingly low, but there is no drop in the incidence of cancer by 40% among them. For example, male athletes have cancer 11% less often than their non-athletes peers.
Yes, there are groups of athletes among whom the probability of cancer is even lower than that of the Amish. These are middle-distance runners, they get a malignant tumor 49% less often than ordinary people, long-distance runners are 43% less likely. Track and field jumpers show the same "minus 40%" as the Amish. However, all these sports are extremely far from the activities of the mentioned sectarians. They don't run at all, they just walk, including behind the plow. This means that their loads are not athletics at all and are closer to other sports that cannot reduce the risk of cancer by 40%. Something's eluding us again, right?
Multiply or die
A group of Swiss scientists once thought: how is this so? What is the point of evolution to allow people to have a massive "built-in" disease in their genes that prevents reproduction? Evolution has always done everything to improve breeding conditions, selected those who die less often, reproduce better, and then suddenly what, she had a sunstroke?
Researchers have found out how often cancer occurs in people with different numbers of children. "Suddenly" it turned out that evolution had not changed itself. Where women in families gave birth to an average of 7.5 children, the probability of getting cancer over a lifetime was 2.79 times lower than in families where women gave birth to an average of less than one and a half children.
On the vertical axis, the probability of getting cancer, on the horizontal axis – the number of children per mother in the family. The red line shows the fate of women, the blue line shows the fate of men, the black line shows the average for both sexes / ©Wenpeng You et al.
As we can see, almost any resident of Russia can easily drop the probability of getting cancer at times. The average number of children per woman in our country rarely reaches even two. It is enough to have four, so that the risk of developing cancer drops a couple of times. Moreover, the researchers emphasize that such a ratio was observed after alignment by age groups (that is, taking into account different life expectancy in different countries). After any correction in GDP, urbanization, and so on. This is a general rule, and from a biological point of view it is quite logical.
In fact, from the point of view of evolution, individuals who do not want to reproduce are ballast. They are not just useless, but even harmful: if they did not exist, the material resources available to them would be with those who want to reproduce.
Cancer in a sense serves as a tax on childlessness. Only if such a Soviet-era tax was paid with money, then its biological counterpart is paid with the head. Killing tens of millions of people a year, cancer most of all does it in countries with a minimum reproduction rate, thereby destroying those who, from the point of view of Darwinian fitness, are of little use (small children) or generally harmful (childless).
It is worth paying attention: the rule works not only for women, but also for men. At first glance, this is intriguing. With a woman, everything is clear: when she is pregnant or breastfeeding, she has a different hormonal background and so on. It is easy to imagine a situation where this background somehow affects her resistance to cancer, increasing it. But what about the man? After all, according to the graph above, the probability of dying from cancer in him also depends on the number of children of his long-term cohabitant.
What mechanism allows him to avoid cancer is not clear. It is known that men in marriage may lose some testosterone levels, but regular interaction with loved ones can raise their oxytocin levels. Such hormonal changes can somehow affect cancer resistance, although, of course, today the specific mechanisms of such influence are not clear.
Now it's easy for us to understand why Amish people are 40% less likely than ordinary Americans to get cancer. There are no options: in their families, women give birth to several children, at least 4.2. And the average American does not see from his wife and two. It would be surprising if the Amish did not have a lower incidence of cancer after that than their non-sectarian peers.
By the way, the birth rate of Amish is so high, and the birth rate of their fellow non-sectarian citizens is so small that American demographers even jokingly calculated when absolutely all residents of the States will be Amish. However, this will happen no earlier than in a few centuries, even if it happens.
The imperative "multiply or die" explains quite well both why cancer is becoming more common in the Western world (the birth rate is falling) and why it is "getting younger" there. Let's explain: in a society with good medicine, about half of cancer patients are over 70 years old. That is, the probability of cancer increases with age. For example, in the USA a few decades ago, cancer among people aged 25-39 was relatively rare. And biologically, it seems to make sense: this is the most fertile age. Killing an individual of such an age range, from the point of view of evolution, does not make sense.
However, the birth rate in the States is falling, as elsewhere. The fertile age is accompanied by less and less fertility. Therefore, in 1975-2015, the incidence of cancer among women aged 25-39 there is growing by 1.15% per year, and for men – by 0.46%. Moreover, the process is gaining momentum: by 2030 in the United States, the incidence of cancer in 25-39-year-olds will increase by 11-12%, the authors of the corresponding work are sure.
Therefore, the idea of "cancer is a matter for the elderly" is becoming less and less true. In the future, this process may further intensify, since the number of children per woman does not stand still – and it is not moving up at all.
Should I wait for a cure for cancer?
Over the past centuries, mankind has become accustomed to the fact that clever scientists are inventing more and more medicines for a variety of diseases. These are vaccines against traditional infections, and antiretroviral therapy for HIV. Almost every day, the media tell how new tools are appearing that promise to end cancer. A little more, it seems to us, a little more – and he will be defeated.
Let's be honest: this is not going to happen in any foreseeable future. Many new ways to fight cancer, of course, are extremely useful, since they increase the likelihood of survival for those who have already received a malignant neoplasm. But no more than that. "Vaccines" and medications will never actually be able to make cancer recede. The reason is that vaccines only work effectively against specific types of cells (or viruses).
Once the pathogen receives genetic differences from the "sample" on which the vaccine was trained, it will cease to effectively train the immune system to attack "targets". That is why it is necessary to create new vaccines against influenza all the time: it mutates extremely quickly, in comparison with other viruses. HIV mutates even faster.
But all this is nonsense compared to the variability of cancer. Cancer cells are ordinary human cells, it's just that the work of some genes in them went wrong. Each person's DNA is slightly different from another person, which means that the number of "targets" for cancer vaccines is in the billions. Creating an individual effective vaccine for everyone is something that has been promised to us for years. Only we would not advise betting money–or the hope of saving a life–on such promises.
The situation is similar with medicines. It is extremely difficult to kill a cancer cell (similar to an ordinary human cell) without destroying the DNA-like cells around it. Sometimes it works, often it doesn't. The work of oncologists is like Sisyphus rolling a stone uphill. As soon as they removed the tumor or cured it with radiation or chemotherapy, the cancer cells scattered throughout the body and metastasized there.
The number of years of life of an average cancer patient after diagnosis has increased many times over the past decades. Dark blue color shows the average probability for all types of cancer / ©Macmillan Cancer Support
Doctors greatly raise the chances of survival in this struggle, but they are not working miracles yet. They can increase the percentage of cancer survivors, but they cannot stop deaths from it. The mechanism of liquidation of the small and childless is really complex and effective. Defeating him is an impossible task for today.
There is no need to hope for genetic editing, about which there is so much talk. Firstly, the possibilities of even the best technologies in this area are still small. CRISPR works well and unmistakably only on the pages of enthusiastic science-pop media. In real life, everything is more sad. He systematically rules the wrong genes and the wrong way, and he can't always fix the right ones.
Secondly, it should be understood that in the field of gene editing of people, free breakfasts are often with rat poison inside. We, in fact, do not know the exact functions of all those hundreds of genes, changes in which can lead to cancer. It may easily turn out that by improving them in terms of cancer resistance, we will lose some other function of them: for example, we will lose the work of the human brain with an edited genome. How to avoid this is a difficult question. Fortunately, it is not even worth it yet, because with methods like CRISPR, effective "anti-cancer" gene editing is unrealistic in the foreseeable future.
Will there be recommendations?
We don't like to make riddles: they make a mess in our head. But we have to admit: how to fight cancer for an ordinary modern person is a mystery.
No, it goes without saying that an annual examination by doctors dramatically increases the chances of survival for any sick person. But ideally, it would be good to avoid the disease altogether. However, all the ways to do this look, how to say it .., difficult for a modern person.
Of course, you can become a middle–distance runner - up to three kilometers. But from the fact that professional athletes are "average" (men, for women, alas, there are no such studies in a larger sample) until old age, they get cancer 49% less often than their usual peers, it does not follow that this will happen with you. The running speed of amateur athletes around the world is falling: in the 70s it was noticeably higher than now. Why is this the second question: most likely, the drop in testosterone levels in men is to blame, going by about 1% per year.
The running speed is lower, the load on the body is lower, the factors that reduce the likelihood of cancer are less involved. To drop its probability by 49%, you need to run not "for fun", but for a normal time. Let's say you need to run three kilometers faster than in 12 minutes. Note: this is a conditional figure, the real results of professional runners are even higher and even more difficult to achieve. How many of our fellow citizens would want to do such a thing? Let's not lie to ourselves: the question was purely rhetorical. The anti-tumor effect of physical activity "for pleasure" is much lower and does not affect many types of cancer.
In theory, there is a method of cancer prevention available to almost every healthy person: to have a family and several children. The effect, compared with having no family or one child, will be about the same as with "professional" middle-distance running.
But let's face it: this contradicts what the modern lifestyle has made fashionable. Western countries and the Western way of life serve as cultural models in today's world. Wherever it penetrates, the birth rate inevitably falls – and falls heavily. It is enough to look around on a city street to understand that Russia is a typical example of such a far–reaching Westernization.
It is clearly seen that the birth rate in the world is falling and will continue to fall in the foreseeable future. Consequently, the probability of getting cancer will grow, which is observed in practice / ©Wikimedia Commons
Most of us tend to fall under the influence of lifestyle and values accepted among others. Therefore, the vast majority of residents of a country like Russia will never have several children. In such an environment, even three kilometers in 12 minutes is a more realistic way to "escape from cancer" than having many children.
What other recommendations can be given here? Definitely, you can never smoke (up to a ten percent reduction in the likelihood of cancer). It is possible not to live near coal-fired power plants, since microparticles from non-combustible components of coal are really carcinogenic. Try to inhale less car exhaust and not sit downwind of the fire. In no case should you inhale smoke from plastic, garbage or leaves burned in a fire: there are much more microparticles there than in the smoke from a conventional fire. Avoid standing near a pile of grass or a large fire. Drink less soda: people who consume a lot of it are more likely than others to go to an oncologist.
But all these are banal recommendations that should be followed, even if you have never thought about this disease in your life. And all of them can reduce the incidence of cancer by about a dozen percent, no more.
There are really effective ways to greatly reduce the likelihood of cancer. But it is difficult to put them into practice. And if you are not a professional runner, Amish, a resident of some African countries, or someone else who is just as far from the average person, it is extremely difficult.
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