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|What Causes Cancer?
We still don't know what causes cancer. As there are at least 200 different types of cancer, there is much research still to be completed - most of which is being done through cancer clinical trials. We are however learning more about how cancer happens. Cancer like many diseases is multifactorial, which means many factors are involved. These factors include age, genetics, environmental hazards and lifestyle habits including smoking, drinking and bad diet. The more factors present, the higher the risk of developing cancer. With our present knowledge there is no way that we can say for definite that this or that action caused cancer. Each individual will have different mixtures of reactors including age, strength of immune system and exposure to carcinogen’s (environmental toxins, many of which we do not even know yet).
In order for cancer to be present, there must be: an abnormal cell, a way for it to rapidly multiple and colonize and an immune system which is not strong enough to destroy it. Inside the DNA of every cell there are millions of genes. These genes are the blueprint instructions for the cell - they tell it what type of cell it is, how it is supposed to react, when to divide and how to repair itself. A mistake in just one of those millions of genes produces a change in the cell. This is known as a mutation. Sometimes the mutation might make the cell more efficient (Darwinism at its best), or it may be disastrous causing the cell to die immediately. It may even be that a flawed gene is passed down from generation to generation without noticeable effect. A flawed cell however is always going to be more vulnerable and has a greater chance of turning malignant (cancerous) if other risk factors are present (such as smoking, too much sun etc). Most experts believe that not one single event will turn a weakened cell cancerous, but rather multiple hits. The damage then accumulates to a point where it reaches critical mass and the cancer somehow 'switches on'.
What Causes Cancer To ‘Switch On’?
What causes a cell to 'switch on' and become cancerous is one of the key questions of cancer research. Researchers for example have discovered a gene called p53 which acts to keep the breaks on cell production, so that they don't produce too fast or too slow. If the p53 gene is damaged (for example by some carcinogen like smoking) it mutates and is no longer able to keep cell production or quality in check. In fact scientists have discovered that damaged p53 genes are present in nearly 90 percent of all cancers. The mutation of p53 may happen years before cancer develops, so being able to prevent or reverse this damage appears to offer untold benefits. It is a huge area of cancer research. Mutations in other genes such as BRCA1 and BRCA2 have been linked to ovarian and breast cancer risk factors, see genetic tests for breast cancer for more specific information.
Although we may not yet understand the how’s and why’s of why cells turn cancerous, we do know that certain risk factors can damage already weakened cells, making them more vulnerable to turning malignant. These are:
Carcinogens (Cancer Causing Substances)
A carcinogen is a substance which helps to cause cancer - many of which we still have not identified. Tobacco is considered a carcinogen, although not everyone who smokes it develops lung cancer, which means other factors must also be at play. Other potential carcinogens include asbestos and certain dioxins chemicals. There has been varying evidence over the years linking hair dyes to cancer, in particular the darker hair colors. One study of half a million million showed that those who used black hair dye for more than 20 years had a slight increase of risk in developing non-Hodgkin's lymphoma and multiple myeloma. Another more recent study involving 100,000 women by the Nurses
Study found however found no link. Although there is no strong evidence to suggest women stay away from hair dyes, most clinicians advise pregnant women, particularly in their first trimester of pregnancy, to avoid dyeing their hair. They may also suggest women use natural products like henna instead of most leading brands which contain chemicals.
Age is the single most important factor for cancer, even though many women believe that their risk of developing 'female’ cancers declines after childbearing years. This could not be further from the truth. Nearly 50 percent of cancers develop in people over the age of 65. This is probably because the older a person is; the more likely they are to have been exposed to toxins and other risk factors. Fewer women over 65 have a Pap test which is why if they develop cancer of the cervix it is often diagnosed at a later stage. Women who have had a hysterectomy often neglect to have smears. This is a mistake because remnants of cervical tissue left after the procedure can develop into cancer. The most common types of cancer in women over 65 are breast, followed by lung and colon cancer.
Some cancers occur with great frequency in families. Breast cancer is one example. We now know of at least 3 genes which can be passed from both a mother and father that increases the likelihood of breast cancer and ovarian cancer occurring. In fact it is estimated that nearly 10 percent of all cancers are genetically linked. A mother or father can pass on a gene mutation, but this does not mean that the next generation will definitely develop cancer. Several mutations are necessary for a cell to turn cancerous; but this may happen if the person is exposed to enough carcinogens. The original genetic flaw or mutation weakens the cell making it more prone to further mutations. This is known as genetic predisposition. Many people who develop colon cancer for example have a genetic predisposition.
Race & Ethnicity
Cancer rates are affected by race and ethnicity. For example African Americans have a lower rate of cancer survival than any other ethnical group. This may be partially linked to poverty, lower medical coverage and access to health care. Other unexplained factors may also be at play. African American women have fewer cases of breast cancer than white American women, but once diagnosed, they are more likely to die. Hispanic and Vietnamese-American women are more likely to develop cervical cancer than white American women. When considering cancer among races of people, economic factors as well as social and dietary habits have to be considered.
People with weakened immune systems are more likely to develop some types of cancer. People with AIDS are more likely to develop lymphoma and cancer of the central nervous system. Chronic infections and organ transplants can also increase risks.
Parasites, infections and bacteria can lead to cancer. Hepatitis B virus is linked to liver cancer and T-cell lymphotropic virus is linked to leukemia and lymphoma. Genital warts can lead to cervical cancer and the Epstein-Barr virus (EBV) is linked to Burkitt's lymphoma. Liver flukes have been linked to liver cancer and blood flukes to colon and bladder cancers.
Diet & Obesity
Obesity in women: Scientists believe that by eating a balanced diet, maintaining a healthy body weight and taking regular exercise, as many as one third of cancer deaths could be prevented. Low fiber diets in particular have been linked to cancer. The reason why is not clear but it may be because fiber causes food to pass quicker through the colon, thus exposing the intestines to fewer toxins. High fat diets are also linked to cancer, when the fats break down they produce chemicals which are thought to be carcinogenic. Food additives used in the United States have also been linked to cancer.
Interesting!: Top 10 Anti-Cancer Foods: cancer reducing foods.
Some medications we use to treat conditions are themselves carcinogenic. Synthetic estrogen used for estrogen replacement therapy (ERT) is associated with breast and endometrial cancer. Another hormone DES was given to women to prevent miscarriages but it was linked to cancer of the vagina, and is no longer prescribed. Coal tar ointments used for the treatment of psoriasis might be connected to skin cancer and amphetamines to lymphoma.
Smoking tobacco causes 85 percent of all lung cancers and 30 percent of all deaths from cancer. It is also linked to cancer of the breast, kidneys, stomach, liver, mouth, bladder and pancreas (see diagram of the human body). Even chewing tobacco is linked to cancer of the mouth.
Exposure to Sun
One million cases of skin cancer a year can be traced to over-exposure to sun. A thinning ozone layer certainly is not helping! Fortunately most of these cancers are curable with specific cancer treatments. Malignant melanoma however is an exception as it is a deadly form of skin cancer. People most at risk are the old, and those with fair skin who burn easily. Heredity factors may also be involved. Always wear a skin factor protection of SPF 15, and reduce time spent in the sun between 10am and 4pm.
|Related Articles on Cancers
For more advice on female cancers, see the following:
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