Did You Know That Cancer Evolves? Can It Be Prevented?

Preventing the spread and development of cancer and the harm that accompanies them, and finding treatments and a cure for cancer, have been among the main aims of oncology departments. Approaching cancer from an evolutionary perspective may lift certain veils of mystery. To discuss this subject, we first need some basic information.

About Cancer – What Is Cancer?

Cancer, which arises from the nature of the principles of life, can be described as a side effect of the workings of evolutionary mechanisms. Accumulated DNA damage (and, in some cancers, viral factors) causes cells to grow uncontrollably and to undergo metastasis (spread) to healthy parts of the body. This group of diseases is called cancer.

Most often, the cause of this uncontrolled division is unplanned changes in the genetic code. Mutations, as these changes are called, can occur in various ways: sometimes UV radiation disrupts the structure of DNA, and repair systems do not have the capacity to repair this damage completely; sometimes DNA is copied incorrectly, and correcting the error during replication is missed; and sometimes the amount of toxic material in the environment affects the cell's topology, interfering with the proper functioning of its division systems (topology is the branch of geometry/mathematics that studies the properties of surfaces and general shapes, but is not concerned with lengths and angles). In such situations, the DNA repair system, apoptosis (programmed cell death) or the immune system comes into play. When cancer develops, there is a weakness in these control mechanisms. For example, a weak immune system will be less effective at dealing with mutated cells than a strong immune system. Alternatively, some people may have specialized immune system cells that recognize cancer cells better (for example, these specialized immune cells have been identified in people over 100 years old; see the related discovery).

Figure explanation: The upper part illustrates conditions that cause DNA damage, while the lower part depicts the most common mechanisms for repairing this damage.

Cancer is a phenomenon that, at its least severe, reduces quality of life and, at its most severe, ends life.

The ability of cancer to develop in many cell types is its most important initial advantage. The most apparent underlying reason is that as cells become more complex during evolution, repairing the various systems that develop alongside them becomes more difficult; repair components have not yet been optimized, or the system or systems needed to optimize these components are not present in the cell. This is why, as organisms become more complex, cancer evolves with them and continues into the future. As long as evolution exists—that is, as substances change from one form to another over time—organic structures that fit our definition of "cancer" will also exist. However, recent work by humanity has offered a ray of hope and contributed to efforts to prevent many of the types of cancer we know.

There are 4 main types of cancer

1. Arising in glandular and epithelial tissues and forming solid (solid, organ) tumors, carcinoma is the most common type of cancer. Prostate cancer, breast cancer, lung cancer and colon cancer fall under this umbrella.
2. Also known as soft tissue cancer, arising in muscles, nerves, fat, tendons, blood vessels and similar structures, and forming soft tumors, sarcoma is a rare type of cancer.
3. Leukemia, also known as blood cancer, is simply the uncontrolled production of abnormal white blood cells in the bone marrow. Instead of dying after a time, these abnormal white blood cells continue to multiply. This means there will be little room left for red blood cells in the blood, reducing the amount of oxygen carried and delivered. Tumor formation is generally not observed.
4. Lymphoma develops in B, T and natural killer lymphocytes (types of white blood cells involved in identifying pathogens). Tumor formation may be observed.

There are 2 main types of tumor:

1. Benign tumors do not metastasize, are usually surrounded by connective tissue, and divide for a certain period. Their characteristics are more similar to those of normal cells. However, because of the compact structures they form, they can damage nerves, reduce blood flow, indirectly cause ischemia-related gangrene, damage organs and so on. Low levels of angiogenesis (new blood vessel branching) are observed around benign tumors, and this plays an important role in their inability to grow rapidly or metastasize.
2. Malignant tumors can metastasize and multiply in an extremely uncontrolled manner. These tumors may disrupt the activity of an affected organ directly or indirectly. A direct example is cancer developing on a structure and affecting its activity; an indirect example is blood-borne oxygen and nutrients being used predominantly for tumor growth when excessive angiogenesis is observed. At the same time, a high rate of angiogenesis also greatly enhances the capacity to metastasize. Tumors that show a tendency to become malignant are called premalignant tumors. Premalignant tumors must be kept under close observation, or they may become malignant.

Not every cancer forms a tumor, and not every tumor is diagnosed as cancer Most benign tumors will go away on their own or remain with you, like some skin tags on your body (see: the difference between moles and skin tags). Certain criteria apply to skin tags becoming cancerous; some may be warning signs of cancer.

What Is Evolution?

Before discussing the evolution of cancer, we also need a definition of evolution . Although evolution is often explained primarily in biological terms, it should essentially be presented as the law governing how our universe works. Evolution is the accumulation of small changes over time into major differences. It is something that originates from an earlier form and eventually becomes something new through small changes. Beyond living things, this applies to everything in the world. Let us look at it this way:

You can see this phenomenon everywhere, at all times, in every field. Things that occur over long periods—such as people's personalities, exchanges between cultures, the movement of continents, changes and developments in musical instruments, the development of weapons and the increasing number of treatment methods—and things that occur over relatively shorter periods—such as differences in parents' relationships with their children or grandchildren, changes in the perception of music, and today's watermelons having more flesh than those grown a hundred years ago—provide excellent examples of evolution.

What we call evolution, as described above, is a general term. Chemical evolution, which studies the evolution of molecules and the formation of new substances; physical evolution, which studies the laws of physics that have gradually settled into order since the Big Bang (and, indirectly, chemical, cosmic and biological phenomena); and biological evolution, which studies life and the complexities contained within living organisms, are the three main branches of evolution. These three main branches have led the way for countless branches of science.

The concepts of macroevolution and microevolution divide evolution into two groups based on the time it takes for evolution to reach a new stage. Macroevolution describes the accumulation of changes over a long period, whereas microevolution describes changes that occur over a relatively short period. The examples in the second paragraph under this heading were written to correspond to macroevolution and microevolution, respectively.

What Is the Difference Between a Theory, a Law and a Phenomenon?

Now that we have "briefly" explained evolution, let us look at the difference between evolution and the Theory of Evolution by considering—again "briefly"—the difference between a theory, a law and a phenomenon:

People sometimes being selective when conveying information to one another has led to important points being forgotten over time. The definitions of theory and law have suffered through years of conflict between curricula. These two scientific terms are tools with completely separate functions that cannot be transformed into one another. We should remember that both are based on scientific methods and are built up from small components into larger ones. Both need experiments and require firm evidence. Although they resemble one another in these respects, they do not resemble one another in the following respect:

• A theoryis used to explain a phenomenon. Theories originate from hypotheses based on observations. They need a considerable amount of evidence to explain a phenomenon fully. There is continuous research into these phenomena, and support is drawn from many scientific disciplines to make the explanation offered by the theory increasingly accurate and acceptable. Economic Theory, Information Theory, the Theory of Evolution, the Theory of Relativity, the Big Bang Theory and Cell Theory are good examples.
• A lawis used to describe a phenomenon. Laws also originate from hypotheses formed from observations. They are established according to whether experiments conducted around the world on the phenomena they describe yield the same result, and whether they can form a foundation for science. Theories, in turn, explain laws; laws describe the phenomena used within theories. This duality is very important for the progress of science. Examples include the use of the Law of Gravity in the Theory of Relativity, Ohm's Law in Circuit Theory, and the Law of Conservation of Mass in Kinetic Theory.
• Phenomena are observable things that are researched, from which hypotheses are formed, and on the basis of which a law or theory is developed through lengthy, demanding work. Although they involve assumptions, they are not themselves assumptions. The concept of a phenomenon accepted in science is based on ontological materialism: however supernatural or outside nature a phenomenon may appear, it can ultimately be explained and traced to its origins through the mechanisms of the universe. Because this perspective is consistent with the mechanisms that science studies and investigates, scientists accept and use it.

Consequently, the difference between evolution and the Theory of Evolution can now be seen clearly: Evolution is a phenomenon, whereas the Theory of Evolution is a tool for explaining and making sense of that phenomenon and establishing the foundations needed to study it.

Now let us look at evolution and the oncological interpretation of the Theory of Evolution, which explains biological evolution (a curriculum topic).

The Evolution of Cancer: Evolutionary Biology and Adaptive Therapy

Figure explanation: As cells divide, they acquire mutations that can enable abnormal growth and the formation of tumors. Tumors and their metastases may consist of various groups of cells. In other words, metastatic tumors may have a phenotype (appearance) and genotype (genetics) that are very different from those of the original cancer cell.

Cancer cells can form anywhere in our body. This is why cancer can be observed in many different cell types. To understand the evolution of cancer, let us first look at how cancer develops in our body.

Cancer may arise in germ cells (our reproductive cells) and be passed to later generations as an inherited trait (hereditary breast or ovarian cancer), or it may arise in somatic (body) cells and remain confined to our body (see the concepts of familial, hereditary and sporadic cancer). In either case, certain criteria apply to the development of cancer. Most of these criteria are evolutionary pressures.

Evolutionary pressures, briefly, are factors that cause an organism to change in a positive or negative direction.

With this in mind, let us examine an ecological example from an oncological perspective:

The most basic aim of living organisms is essentially to survive until reproduction. Many risks also carry the possibility of being unable to mate: competition, hunger, thirst, environmental factors, inherited traits (the ability to express genes and so on), an organism's intelligence, and the efficiency of its hunting methods are among the many factors that play important roles in the continuation of its lineage. Coping with these selection pressures and adapting to the environment created by these factors, successfully passing through reproductive periods, and minimizing the damage sustained throughout this process are defined as an organism'sfitness. In evolution, whatever period in the lifespan of successful organisms the selection pressures shift toward, the period when those organisms are most active and energetic also tends toward that interval. In fact, this is a chaotic process, and only those prepared for future pressures can survive pressures such as these.

Mice in the wild live for approximately 1 year, whereas laboratory mice live for 2 to 3 years. Cancer occurs more frequently in laboratory mice than in their cousins in the wild. One important reason for this difference is that laboratory mice are older. Our cells lose their functions as they age (but remember that around 230 billion new cells are produced in our body every day. The issue here is not so much the death of cells as the loss of function over time in newly formed cells). For the reasons mentioned above, the loss of these functions is, in a sense, very important in shifting an organism's "youth" (the period of maximum energy and optimal reproductive potential) toward the period to which evolutionary pressures have shifted. These changes in the distribution of energy throughout life are directly related to fitness.

- Related topic: Why Does Cancer Occur Mostly in Old Age? Approaches to Treatment in Older People

We can say that mice in the wild already barely reach old age. Their body's cells are therefore still relatively "young", and the groups of cells in their body are at their most efficient and relatively most functional. The high fitness of these cell groups indicates that the systems preventing or stopping cancer formation are working at their most active.

Now let us consider this at the cellular level:

One reason that cells become cancerous is fluctuations in the fitness of the groups of cells in our tissues. Carcinogenic substances—that is, cancer-causing substances such as asbestos, cadmium, nickel and vinyl chloride—can disrupt the normal functioning of certain cell groups in organisms whose immune systems do not function well for their age (in other words, whose capacity to adapt is deficient), and can also cause DNA damage in these cells. When this happens, depending on the cell's ability to repair damage as far as its age allows, its mechanisms may break down and it may become cancerous. In addition, under certain circumstances, carcinogens can cause even highly fit cell groups to become cancerous; this is also partly related to how frequently and at what concentration these carcinogens enter the body (see, when a cancer-causing substance causes cancer).

In addition to cells that become cancerous because of evolutionary pressures, there are also cancer cells that arise from a cancer stem cell (CSC). Every cell in our body begins life as a stem cell in the region where it originates (first forms). Stem cells are cells that have not yet acquired specific functions.

Natural stem cells are divided into adult stem cells and embryonic stem cells. Although both types can essentially develop into many kinds of cells, embryonic stem cells can become every cell type in our body, and their main purpose is to form the embryo. Adult stem cells (stem cells in the bone marrow that form red blood cells and similar cells, neural stem cells that form neurons and so on) have less potential than embryonic stem cells and cannot develop into every cell type in the body. They have a relationship of belonging to an organ system, and their main purpose is tissue repair.

Let us discuss adult stem cells: they live longer than all somatic (body) cells and reproductive cells, and are maintained in certain numbers in the relevant organ. Because our body has evolved not to produce new adult stem cells unless they are needed, there is a risk that mutations may accumulate in the stem cells already waiting to be used. If these cells have accumulated sufficient numbers of particular oncogenic mutations, they may form tumors where they are used. If the mutations they acquire permit metastasis, they are called metastatic cancer stem cells (MCSCs). Research into this subject is still ongoing; mapping metastasis at the molecular level and understanding how stem cells become cancerous may be important in defeating cancer.

There are 3 types of genes associated with cancer

These are:

How Will Evolutionary Biology Help Us Defeat Cancer?

The answer to this question can again be linked to selection:

Chemotherapy is often successful in shrinking tumors, but under certain circumstances cancer can find a way to recur or return (see how frequently different cancers recur). This "way it finds" is the part that concerns evolutionary biology. Natural selection is the basis on which the Theory of Evolution explains stronger cancers that recur after chemotherapy sessions, drawing on the concept of "survival of the best adapted", also known as "survival of the best" or "survival of the strongest" (survival of the fittest). Chemotherapy does more than destroy cancer cells in the area where it is administered: it also damages healthy cells, although to a lesser degree. The cells that survive this "chemotherapy bombardment" are therefore cells with high fitness. Naturally, these cells are expected to be those most open to mutation and most prone to change—in other words, cancer cells. If even a single cancer cell survives, the tumor may still recur. Nevertheless, in cancers that are highly sensitive to chemotherapy—particularly testicular, colon and breast cancers—a cure (complete treatment) can be achieved with chemotherapy.

The problem of drug resistance in cancer is being addressed by trying adaptive therapy (AT). Although portrayed as a more demanding and unnecessary method, AT is a form of therapy based on causing the least possible harm to the patient. In this approach, cancer cells are allowed to have their own territory and to maintain fitness within it. Thus, the energy they would spend on systems that enable proliferation (multiplication) is instead spent on keeping the fitness of the cell group stable. The phenotypes of the cells in this cancer group (topological properties, which in the context of cancer can be described as "the reflection of resistance-conferring gene expression in physical characteristics") are kept homogeneous. This homogeneity is then exploited, minimizing the number of cancer cells that survive the bombardments directed at this group of cells with similar phenotypes.

This approach reduces damage to healthy cells. It also prevents cancer cells from climbing the steps of evolution and, indirectly, accumulating resistance upon resistance. Consequently, the chemotherapy dose required for these cells is also low. By keeping the dose that will also affect healthy cells low, it minimizes the energy that cancer cells reserve for systems such as proliferation and toxin pumps and, in the best case, prevents the cancer from recurring.

However, with the development of immunotherapy and cancer treatments directed at genetic targets, interest in adaptive chemotherapy has declined.

Conclusion

Cancer is one of the fastest-evolving diseases, and the speed of its evolution corresponds to the intensity of the evolutionary pressures applied to it. Apart from therapy, these pressures mostly depend on natural environmental and genetic factors. As these factors are clarified in the light of the Theory of Evolution, we discover, and continue to discover, ways to make the therapies available to us more effective.