Cancer can start almost anywhere in the human body, which is made up of trillions of cells. Normally, human cells grow and divide to form new cells as the body needs them. When cells grow old or become damaged, they die, and new cells take their place.
When cancer develops, however, this orderly process breaks down. As cells become more and more abnormal, old or damaged cells survive when they should die, and new cells form when they are not needed.
Cancer cells have unique features that make them "immortal" according to some researchers.
Mutation is the main tool of evolution. However cancer represents a negative mutation in the sense that it destroys the host and therefore it destroys cancer itself.
Therefore I would not consider cancer as an evolution. The cancer cells are mortal because they die when their host dies. So lets better call it an involution instead of an evolution.
Mutation is the main tool of evolution. However cancer represents a negative mutation in the sense that it destroys the host and therefore it destroys cancer itself.
Therefore I would not consider cancer as an evolution. The cancer cells are mortal because they die when their host dies. So lets better call it an involution instead of an evolution.
Dear Fatemeh, Very important question. I do not know the answer. Evolution implies new generations and evolution considers human not as a unit.
Immortality is not my view in evolution but selection is part of evolutionary processing. I have your question in mind for a long time and, I am happy to read you. In order to cure cancer, it is important, I think, to find new pathways to visualize the cancer question under new philosophical and biomedical views. There are two major questions in cancer, cure the unit/human during his unique life, and visualize health equilibrium in human population.
@ Antimo,
Immortality is necessary for unlimited growth in the primary host (the cancer-brearing individual). Beyond that, if there is no mechanism for transference of the genetic material to a new organism upon death of the first "infected" or tumor containing individual, then it is an evolutionary dead end. It cannot continue after the host dies. Infectious diseases evolve to pass themselves on to more hosts of the same or different species, but if all hosts die, they die and become extinct.
Dear Antimo
Evolution has no goals. It simply happens. You may call it a "biologic accident". But there is no aim in it.
Unless you want to look at it from a religious or filosophycal point of view. Nobody planned evolution. That is why it simply is there with no purpose at all.
I think we can detect different combinations a propos of general question evolution / cancer. Looking within the separated Unit: 1) cell population ‘normal’ versus 1st ‘abnormal’ cell; a) is there any evolutionary break switched on? b) The 1st abnormal cell keeps on the mechanism of reversibility?
2) Abnormal cell gains stem cell properties and proliferates, abolishes contact inhibition and differentiation properties, no apoptosis – immortality>>>. This is a second evolutionary break. No possibility of reversion. The final break comes on by ‘cure or death’ of the unit. So, 1st cell selection, ‘abnormal’ cell, dominates the unit.
There comes the 3d evolutionary step which obliges to compare unit and population. If, the Human and in extension human’s life is not a closed system; then there is definitely a cross-talk between unit and environment. We cannot exclude that the selection conditioning responsible for the appearance of 1st abnormal cell originates from the environment and though we can talk for a cancer as a ‘targeted selection’. The new acquired proliferation properties of 1st abnormal cell suggests that “selection’ forced the target cell to survive versus differentiation and this is a property of evolution.
Under this hypothesis, we should also observe and view the 1st abnormal cells and the following dormant or active as potential evolutionary targets. Therefore might be important to think not to target them with chemo toxic means as chemotherapy and radiation but by differentiation means, which will permit to control proliferation and cell identity. There are certainly more combinations on this topic.
it seems that a way of human evolution is preprogrammed, but a way of cancer evolution can partly be considered as a mechanical response
Cancer uses evolutionary methods like mutation and Darwinian selection. But that does not mean it is an evolutionary process because cancer cells only transmit these traits in an endogamic way. That means between themselves.
If the treatment is successfull cancer cells die. If it is unsuccessful the host dies and with him the cancer cells die too. Ergo death and no transmission to descendants of their traits invalidates the idea that cancer is an evolutionary process. It only evolves towards its own death without leaving any descendants. That is no evolution.
Evolution is not restricted to individuals, humans. Cells, bacteria environment evolve under the space/time dimensions. A cancer cell evolves from a normal cell and becomes a proliferating cell, which means that the “program” of its differentiation or death was overcome. Might be genetic reason might not.
What is critical is that this particular cell was able to evolve and bypass control.
It became a free/independent cell. This is an evolution phenomenon. The transmission of the information to next generation is not of importance at this point.
The question of cancer is to cure and to understand. If, the “freedom” of cancer cell links to neuro-immuno system of the individual and/or the environment from bacteria to neurotoxins then would be nice to make a link.
Sorry to disagree Vassilis. Cancer cell is not a fully independent cell. It still depends from the host for survival. The day the cancer cell is able to live outside its host and without external help lika a Petri dish with nutrients, will be the moment to call it evolution.
Lets not confuse clonal evolution within the tumor bulk with a biological evolution in nature.
It is now easily accepted that cancer is mainly linked to stress ; junk food; cigarettes and alcohol. For this reason; even young people have cancer now. We are very far away from the natural way of life.
@ Tomas, why not a clonal is not biological??
Human is not an independent unit. It depends from the environment for survival. Ecoli depends on resources etc. Nature does not work upon our views....
Biological evolution is a global phenomenon which drives from one modification to another one. Every modification is unique. I do not uderstand the difference between what you call biological and clonal?? Bios is Bios period. Selection of Ecoli on petri or in Nature is a clonal one as it is the selection of a cell on drug screening or during development. All are biological selections. This is evolution.
We are just observers and an observer and investigator should learn to observe and not use predefinied protocols/ideas to advance science in particular when has to deal with cancer therapies. You know very well how succesfull cancer therapies and predefinied protocols are...When we give 2-3 years under chemotherpy to a human/patient then we have to be replaced by an evolutionary process.
Dear Vassilis
The question was if cancer is a form of human evolution. And it is not. So lets not mix human evolution with clonal evolution.
One more issue. Evolution is not only a mutation. If the mutation kills the host it is absolutely not evolution but involution as I have previously said.
Dear Tomas; I agree that the question was concrete. From my point of view clonal and human evolution are not different. Human is both a unit and a population. Nature should associate these two incommensurable properties.
There are different views on cancer and evolution. See pp below and more. Certainly the field is of interest. Regards, Vassilis
How cancer shapes evolution, and how evolution shapes cancer
Matias Casás-Selves and James DeGregori ; Evolution (N Y). 2011 Dec; 4(4): 624–634.
doi: 10.1007/s12052-011-0373-y
PS. During one life, a cell becomes a human, this is also evolution. We observers, we consider we are humans. Nature's view is different. Nature is looking for an equilibrium energy matter space...
Dear Tomas,
Mutations is only the a step of the evolution. The most important steps of the evolution are inheritance and environmental selection pressure. Evolution is not a simple phenomenon, but it depends on several factors. People sometime transmit genes of the inherited diseases, but these genes are not benefeit for the species. For these reason I believe that cancer is not a step of the evolution.
Further to Gennaro Riccio, mutations are beneficial or harmful, depending on the selection pressure; e.g., sickle cell syndrome has remained in some populations because although persons with +/+ express the mutation and die of the disease, persons who are +/- have a benefit in regions where malaria is endemic. Until recently, when anti-malarials have become more avialable, the +/- genotype (50 % of offspring of a +/- to a +/- mating) had a selective advantage. In areas where malaria is absent, the advantage disappears, and the disadvantage becomes something to treat. Many heritable human mutations are disadvantageous in some environments and beneficial in others. Eliminating such mutations through germ line gene therapy would be disadvantageous to the population at large should the environment change and these mutations could save our species. The Black Death (plague) that eliminated much of the population of Europe in the middle ages (25-50%?), selected for those with resistance to this disease. Hence it was not as devastating in subsequent recurrences.
Cancer kills the host, so the mutations that lead to it cannot contribute to human evolution, except by eliminating those who get the mutations in their germline.
partially, I think we can interpret cancer phenomenon as an evolution procedure; alas, we are intermediate generation bearing the death toll. may our body intend to design a new organ or systems like lymphatic tissue or whatever. for example, the rate of cancer incidence in the heart is dramatically down (may there is not anybody who bears heart cancer) because these kinda genes have been deleted (or modulated) through evolution (i am not sure about animals but in human heart cancer is not possible to occur) and now the same thing gonna happen for cancer.
BEst,
You may have a look at this link for further information:
https://www.scientificamerican.com/article/evolved-for-cancer-2008-07/
May be we should clarify what is evolution.
Of course, cancer cells evolve in a Darwinian fashion
This does not mean that cancer is an evolutionary aspect of the species.
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