The causes of skin cancers are not that well known but scientists and doctors have linked skin cancers to certain factors. Among the not so well known skin cancer causes is that people who are of fair skin and therefore have less amount of melanin are more susceptible to developing skin cancer. However, there is no real known skin cancer causes though it is believed that squamous cell carcinoma as too basal cell carcinoma are thought to be related to sunlight’s accumulation during a person’s lifetime, and that people with fair complexion are more susceptible to developing such tumors than those with dark complexion.
There is almost unanimity in believing that among the major skin cancers cause is exposure to the sun since ultraviolet rays from the sun can damage the DNA and cause mutations, that in turn will lead to the development of skin cancer, and that according to estimates, two thirds and more of all malignant melanomas and as much as ninety percent of non-melanoma skin cancers are attributed to high degree of exposure to the sun. An overexposure to UVB radiation can cause sunburn and some forms of skin cancer. In humans, prolonged exposure to solar UV radiation may result in acute and chronic health effects on the skin, eye, and immune system. However the most deadly form - malignant melanoma - is mostly caused by the indirect DNA damage (free radicals and oxidative stress). DNA absorbs UVB light and the absorbed energy can break bonds and DNA nucleotides. Most of the DNA breakages are repaired by proteins present in the cells nucleus but unrepaired genetic damage can lead to mutations and a build of mutated cells can cause cancer (uncontrolled growth of abnormal cells) This can be seen from the absence of a UV-signature mutation in 92% of all melanoma. Furthermore, it is also believed that among the probable skin cancer causes are people having fair skin, red or blond hair, blue, hazel or green eyes, freckled faces, those whose skin tans poorly and burns easily, people with plenty of moles, and those who have a family history of skin cancer are more likely to develop skin cancer. In the same vein, if your skin is of dark colour, you would be twenty times less at risk of developing skin cancer than is the case with Caucasians.
Judy’s mole had also undergone some changes which she noticed and upon looking at the mole Mariah thought it could be cancerous. Some characteristics the mole had were that it had grown a little which could be due to an overgrowth in abnormal cells. It was also sort of jagged. One edge was a bit darker than the other and in the middle was a raised purplish-black dot that she tried to wipe away but couldn't.
Part 2
All tumors are is a build up of cells that have divided and piled up on one another in a single mass. A benign tumor is a tumor where there is a build up of normal looking cells in one area and therefore these cells are not cancerous thus the tumor is not cancerous. So in benign tumors the cells would not spread and cause problems. In a malignant tumor the cells that have built up are abnormal cells that have overgrown and piled up together these however, have the ability to metastasise (spread to other parts of the body). So in treating a benign tumor you would be able to focus on one are where the tumor is and removing it and just have periodical check ups with your physician. When compared to treating a malignant tumor where cells spill over in to neighbouring tissues and spread throughout the body spreading toxic cancerous cells. It would be harder to kill all the cancer cells that have reproduced and divided and invaded other body organs and tissues. After removing the malignant tumor you would have to go under all kinds of procedures to kill the remaining cancerous cells such as radiation and chemotherapy.
Under normal circumstances our bodies might need to make more cells in the event that we are injured and body tissues are lost. The way we heal is by the regeneration of cells basically. In an event where a person gets a deep cut the cells are regenerated and a mass of cells grow where the skin tissue was lost. The skin will not heal as it looked before unless the person received stitches, but you will be able to see new skin forming which at the most basic level is just cells dividing. When a person is burnt the same process will occur. All these calamities add up to a loss of cells so basically the body might need to make more cells when the body loses some cells irregularly by some unfortunate series of events.
Proto-oncogenes are normal cellular genes, these genes code for proteins that stimulate normal cell growth and division. The proto-oncogenes are the genes whose products stimulate normal progress through the cell cycle. Cyclins and cyclin-dependent kinases (CDK) are examples of products encoded by proto-oncogenes. The Cyclin-CDK complex act as maturation-promoting factor which deals directly with the maturation of cells and their division. So if the proto-oncogenes are functioning properly no cancerous cells will be given rise to. So if this proto-oncogene malfunctions or becomes mutated into the cancer causing cell cycle oncogene gene then that person may acquire cancer. In general an oncogene arises from a genetic change that leads to an increase in either the amount of the proto-oncogene’s protein product of the fundamental activity of each protein molecule. This mutation might be due to movement of DNA within the genome, amplification of a proto-oncogene, and point mutation in a proto-oncogene. A proto-oncogene ending up in the joint region may now lie adjacent to an especially active promoter that increases transcription of the gene, making it an oncogene. An increase in gene expression can also arise when a proto-oncogene comes under the control of a more active promoter by transposition of either the gene or the promoter within a chromosome. The second main type of genetic change, amplification increases the number of copies of genes in the cell. The third likelihood is a point mutation that changes the gene’s protein product to one that is more active or more resistant to degradation that the normal protein. All these methods can lead to uncharacteristic stimulation of the cell cycle and put the cell on the course to malignancy.
In addition to that while all persons have proto-oncogenes and some have cancer and some don’t the cancer may be due to the fact that Tumor suppressor genes or the DNA repair genes are malfunctioning. Tumor suppressor genes are genes whose products prevent or inhibit progress through the cell cycle as the name suggests inhibits an overgrowth of cells. Any mutation in this gene that decreases the normal activity of this gene may contribute to the onset of cancer, to all intents and purposes stimulating growth through the lack of suppression. Mutations in DNA repair genes may contribute to cancer by allowing DNA damage in proto-oncogenes and tumor suppressor genes to persist and cause mutations in those genes when the DNA replicates.
Part 3
Risk factors for melonoma are numerous and you have to avoid the ones that you can because melanoma is a highly lethal form of skin cancer and is difficult to treat. So the risk factors you can avoid you should. Some of these risk factors include Dysplastic moles (nevi) are common, and many people have a few of these abnormal moles. The risk of melanoma is greatest for people who have a large number of dysplastic nevi. The risk is especially high for people with a family history of both dysplastic nevi and melanoma. Many ordinary moles (more than 50), having many moles increases the risk of developing melanoma. Fair skin is another risk factor, melanoma occurs more frequently in people who have fair skin that burns or freckles easily (these people also usually have red or blond hair and blue eyes) than in people with dark skin. Caucasians get melanoma far more often than do black people, probably because light skin is more easily damaged by the sun. Personal history of melanoma or other skin cancers, people who have been treated for melanoma have a high risk of a second melanoma. Some people develop more than two melanomas. People who had one or more of the common skin cancers (basal cell carcinoma or squamous cell carcinoma) are at increased risk of melanoma. Family history of melanoma, melanoma sometimes runs in families. Having two or more close relatives who have had this disease is a risk factor. About 10 percent of all patients with melanoma have a family member with this disease. When melanoma runs in a family, a doctor should check all family members regularly. Weakened immune system, people whose immune system is weakened by certain cancers, by drugs given following organ transplantation, or by HIV are at increased risk of developing melanoma. Severe, blistering sunburns, people who have had at least one severe blistering sunburn as a child or teenager are at increased risk of melanoma. Because of this, doctors advise that parents protect children’s skin from the sun. Such protection may reduce the risk of melanoma later in life. Sunburns in adulthood are also a risk factor for melanoma. Ultraviolet (UV) radiation, experts believe that much of the worldwide increase in melanoma is related to an increase in the amount of time people spend in the sun. This disease is also more common in people who live in areas that get large amounts of UV radiation from the sun. In the United States, for example, melanoma is more common in Texas than in Minnesota, where the sun is not as strong. UV radiation from the sun causes premature aging of the skin and skin damage that can lead to melanoma. Artificial sources of UV radiation, such as sunlamps and tanning booths, also can cause skin damage and increase the risk of melanoma. Doctors encourage people to limit their exposure to natural UV radiation and to avoid artificial sources.
To be predisposed simply means that the person is genetically at risk for cancer. That person has done nothing to acquire cancer but in there genes they may have been born with mutated genes that help regulate cell division in the cell cycle. More likely the genes that inhibit cell division which are the Tumor suppressor gene (TSG) will be the ones that would cause a person to be predisposed to cancer if mutated. Usually two TSG’s are inherited, but occasionally some persons only inherit one good TSG so this person would have been born this way. With one good TSG that is enough to keep the cells from dividing abnormally. So ignoring all other factors if you were born this way you would not get cancer, but if the other TSG were to get mutated but some unfortunate series of events like laying in the sun that person would probably get skin cancer from exposure to UV radiation. So a person with one TSG is predisposed to cancer because that person is more susceptible to getting cancer than a person with two TSG’s. If a cell cycle gene is inherited it does not mean that you will get cancer automatically because the other gene is still fully functional and inhibiting overgrowth of cells in the cell cycle this person again would just simple be more at risk to become a cancer patient when exposed to risks for melanoma and other skin cancers. So they would just have to be aware and stay away from any risks for skin cancer. If a person were to ignore the risks for skin cancer and sunbathe or take part in other risky behaviour it still does not mean that they will automatically get cancer some day. This person is just giving themselves more of a chance to contract skin cancer at the end of the day if cell cycle genes become mutated or the cells themselves become mutated, but this doesn’t always happen and doesn’t always have to be the case.
Cancer is a tricky thing and it is very important to know about it. Important things to know are both good and bad. Cancer is a bad thing and it is very important to know about it so that we as humans can’t prevent it by knowing how it happens and what the risks are and to stay away from those risks as far as possible. People need to know to protect themselves and many of the popular beliefs among laymen are not true and they need to educate themselves about these truths. Skin cancer is not only an “Old People’s Disease”. It is true that cancer is usually for old people because of how cancer works and manifests itself after years of accumulating mutations in their genes but contrary to that belief it is becoming prevalent among the young people and they need to know that they are at risk as well; because they may be predisposed and that in itself speeds up the process. Cancer is a killer it discriminates against no man.
References:
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Campbell and Reece. Biology 6th edition Benjamin Cummings publishers 2002 San Fransico pgs368-372
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Fairbanks, D. J. & Anderson, W. R. Genetics: The Continuity of Life (1999) Brooks/Cole Publishing USA pgs 705-715
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Garland C, Garland F, Gorham E (1992). Could sunscreens increase melanoma risk? Am J Public Health Germany pgs 614–5.