Tag Archives: Cancer

Evolution and Cancer

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In order for a cell to become cancerous, it must overcome a great number of biological safeguards. One of the hallmarks of cancer cells is unrestricted cell growth. Cell growth is highly regulated through different growth control checkpoints. These checkpoints serve as gatekeepers that only allow healthy cells to grow. Early in cancer development cancer cells become unresponsive to these checkpoints facilitating unrestrictive cell growth. In addition to avoidance of cell control checkpoints, cancer cell must also acquire the ability to sustain their own growth, avoid cell death signals, overcome environmental challenges such as nutrient deprivation, lack of oxygen and evade the immune response. Driving this multi-step processes is evolution through natural selection.

Evolution through natural selection requires at least two components: first is the generation of “genetic diversity” and the second is the selection of those genetic variants that may confer an evolutionary advantage.

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In cancer cells, genetic diversity arises through the accumulation of mutations. Mutations are changes in the genetic code that may or may not alter the function of a protein. Most mutations are either deleterious or neutral. However, in some rare cases a mutation may give cells an advantage over other cells, allowing the mutation to overtake the population. This process is generally referred to as selection. Selection of a particular mutation is contingent upon the environmental context in which the mutation is present. Some mutations can be advantageous in a particular environment, whereas in other environments they can be disadvantageous.

It is thought that early in cancer development cells acquire what is called a “mutator phenotype”. This means that cancer cells develop the capacity to increase the number of mutations they acquired per generation. This directly increases the pool of new traits that can be selected enabling cancer formation, progression and metastasis. Intrinsically cancer is an evolutionary problem. Cancer treatments have to constantly be ahead of cancer’s ability to develop resistance to chemotherapeutic through natural evolutionary processes. This accentuates the necessity for better understanding of these processes and the concomitant development of therapies that avoid such evolutionary traps.

For Information about cancer:

http://www.cancer.org

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5 things to know about cancer

I have been greatly touched by friends who have battled cancer over the years. Some are still fighting the good fight others have won it and sadly others lost it. In their memory I hope that this post serves as a general introduction to cancer origin and progression.

1. Cancer is not a single disease.

Cancer is a collection of diseases that are characterized by uncontrolled cell growth and invasion of other tissues. There are more than 100 types of cancer with different levels of aggression and responsiveness to treatment. Thereby there is not a single silver bullet to treat all cancers.

The American Cancer Society

2. Cancer is caused by accumulation of mutations.

The underlying cause of cancer is the accumulation of multiple changes to our genetic code (DNA) referred as mutations. The accumulation of these mutations causes cells to become unresponsive to cell growth-governing functions thus allowing for uncontrolled growth.   Uncontrolled cell growth, in turn, further facilitates the accumulation of other mutations that may cause cancer to develop into more aggressive forms. 

3. Family history and environmental factors can increase risk of cancer.

Family history of cancer and environmental factors such as smoking, heavy drinking and STDs can predispose/cause someone to develop cancer.

Family History

Family history of cancer may be due to a genetic predisposition.  Genetic predisposition refers to an inherited mutation(s) that may predispose someone to develop a disease.

Breast cancer is a classic example of genetic predisposition.  Studies show that in the general population about 12% of women will develop breast cancer at some point, however, it is estimated that between 45% to 65% of woman with a pre-existing mutation will develop breast cancer.  The culprits are the breast cancer related genes BRCA1 and BRCA2.  Both of these genes are involved in DNA damage repair. Mutations in these genes may adversely affect the normal function of these genes allowing for the accumulation of additional mutations that may lead to cancer. Men and woman with mutations in these genes have a greater risk of developing breast cancer.

For more information about BRCA1 and BRCA2 visit:

National Cancer Institude

Environment

Environmental factors may increase the risk of cancer.  Substances that cause mutation that may lead to cancer are called carcinogens.  Exposure to such substance can lead to cancer. A great example is cigarettes smoke. According to the CDC cigarette smoke contains more than 7,000 chemicals, 70 are carcinogens. Over time, the constant exposure to these carcinogens causes the accumulation of mutations that eventually will lead to lung cancer. That is why a smoker is 15 to 30 times more likely to develop lung cancer than a non-smoker.

4. Cancer formation is a multi-stage process that can take decades to develop.

Cancer develops in a multi-step process that can take decades to complete. Thereby most cancers affect people later in life. For example, in order for a cell to become cancerous, it must overcome biological safeguards such as growth control checkpoints and cell-death inducing signals that prevent cancer formation. In addition to these biological safeguards cancer cells must also cope with environmental challenges such as nutrient deprivation and lack of oxygen that restrict their growth and ability to invade other tissues. Moreover, cancer like infectious disease has to evade the immune response.

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Natural selection drives these processes. Natural selection is an evolutionary process in which the fittest individuals are selected; in the case of cancer individuals are cells. Thus, natural selection requires diversity of traits within a population and the selection of those traits that are beneficial. This diversity arises mostly through mutations. Most mutations are either bad or neutral. However, in some rare cases a mutation may give cells an advantage over other non-mutated cells. In cancer, a beneficial mutation translates into the ability to proliferate independently of cell growth inhibitors or the ability to secrete signals that will trigger angiogenesis (blood vessel formation) and allow cells to invade surrounding tissues.

It is thought that early in cancer development cells acquire what is called a “mutator phenotype”. This means that cancer cells acquire new mutations at a faster pace than healthy cells.  This increases the pool of new traits and the chances for a beneficial trait that can enable cancer progression.

5. Cancer treatments are different.

Given that there is not a single type of cancer. Cancers respond differently to cancer therapies. For example, a drug that may be effective treating prostate cancer may not necessarily be effective treating breast cancer or leukemia.

National Cancer Institude
American Cancer Society
MD Anderson Cancer Center

If you have a family history of cancer do not be afraid, talk to your physician. Early detention will greatly improve treatment success. Stop if you are engaging in cancer causing behaviors. Life is worth living to the fullest and cancer is not worth it! If you have been diagnosed with cancer and you are undergoing treatment, please remember the words of Christ:

“Everything is possible for one who believes.”
Mark 9:23

Trust in Jesus! He loves you more than anything in this world and keep the fight!

Please consider supporting cancer research and visit:

Johnny Kicks Cancer Foundation.

God Bless.