What Is Cancer? What Causes Cancer?

Cancer has been rampant and more dangerous, people have considered as the most dangerous disease compared to HIV/AIDS, because of its manipulation attacking more than hundred parts of our bodies and also its expensive nature of treatment , if not discovered early it will be disastrous.

Cancer is a class of diseases characterised by out-of-control cell growth. There are over 100 different types of cancer, and each is classified by the type of cell that is initially affected.

Cancer harms the body when damaged cells divide uncontrollably to form lumps or masses of tissue called tumors (except in the case of leukemia where cancer prohibits normal blood function by abnormal cell division in the blood stream). Tumors can grow and interfere with the digestive, nervous, and circulatory systems, and they can release hormones that alter body function. Tumors that stay in one spot and demonstrate limited growth are generally considered to be benign.More dangerous, or malignant, tumors form when two things occur:

a cancerous cell manages to move throughout the body using the blood or lymph systems, destroying healthy tissue in a process called invasion
that cell manages to divide and grow, making new blood vessels to feed itself in a process called angiogenesis.

When a tumor successfully spreads to other parts of the body and grows, invading and destroying other healthy tissues, it is said to have metastasized. This process itself is called metastasis, and the result is a serious condition that is very difficult to treat.

What causes cancer?

Cancer is ultimately the result of cells that uncontrollably grow and do not die. Normal cells in the body follow an orderly path of growth, division, and death. Programmed cell death is called apoptosis, and when this process breaks down, cancer begins to form. Unlike regular cells, cancer cells do not experience programmatic death and instead continue to grow and divide. This leads to a mass of abnormal cells that grows out of control.

There are about 200 different types of cancer. It can start in any type of body tissue. What affects one body tissue may not affect another. For example, tobacco smoke that you breathe in may help to cause lung cancer. Overexposing your skin to the sun could cause a melanoma on your leg. But the sun won't give you lung cancer and smoking won't give you melanoma.

Apart from infectious diseases, most illnesses (including cancer) are multifactorial. This means that there are many factors involved. In other words, there is no single cause for any one type of cancer.

A carcinogen is something that can help to cause cancer. Tobacco smoke is a powerful carcinogen. But not everyone who smokes gets lung cancer. So there must be other factors at work as well.

Most types of cancer become more common as we get older. This is because the changes that make a cell become cancerous in the first place take a long time to develop. There have to be a number of changes to the genes within a cell before it turns into a cancer cell. These changes can happen by accident when the cell is dividing. Or they can happen because the cell has been damaged by carcinogens and the damage is then passed on to future cells when that cell divides. The longer we live, the more time there is for genetic mistakes to happen in our cells.

There need to be a number of genetic mutations within a cell before it becomes cancerous. Sometimes a person is born with one of these mutations already. This doesn't mean they will definitely get cancer. But with one mutation from the start, it makes it more likely statistically that they will develop cancer during their lifetime. Doctors call this genetic predisposition.

The BRCA1 and BRCA2 breast cancer genes are examples of genetic predisposition. Women who carry one of these faulty genes have a higher chance of developing breast cancer than women who do not.

The BRCA genes are good examples for another reason. Most women with breast cancer do not have a mutated BRCA1 or BRCA2 gene. Less than 3 out of 100 breast cancers (3%) are due to these genes. So although women with one of these genes are individually more likely to get breast cancer, most breast cancer is not caused by a high risk inherited gene fault.

This is true of other common cancers where some people have a genetic predisposition – for example, colon (large bowel) cancer.

Researchers are looking at the genes of people with cancer in a study called SEARCH. They also hope to find out more about how other factors might interact with genes to increase the risk of cancer.

People who have problems with their immune systems are more likely to get some types of cancer. This group includes people who

Have had organ transplants and take drugs to suppress their immune systems to stop organ rejection
Have HIV or AIDS
Are born with rare medical syndromes which affect their immunity

The types of cancers that affect these groups of people fall into 2 overlapping groups

Cancers that are caused by viruses, such as cervical cancer and other cancers of the genital or anal area, some lymphomas, liver cancer and stomach cancer
Lymphomas

Chronic infections or transplanted organs can continually stimulate cells to divide. This continual cell division means that immune cells are more likely to develop genetic faults and develop into lymphomas.

Many cancer cases are linked to lifestyle factors such as smoking, alcohol, diet, or being overweight. In the western world, many of us eat too much red and processed meat and not enough fresh fruit and vegetables. This type of diet is known to increase the risk of cancer. Drinking alcohol can also increase the risk of developing some types of cancer. There is more information about this on the page about diet causing cancer.

Sometimes foods or food additives are blamed for directly causing cancer and described as

carcinogenic. This is often not really true. Sometimes a food is found to contain a substance that can cause cancer but in such small amounts that we could never eat enough of it to do any harm. And some additives may actually protect us. There is more about food additives in the page about diet causing cancer.

By environmental causes we mean what is around you each day that may help to cause cancer. This could include

Tobacco smoke
The sun
Natural and man made radiation
Work place hazards
Asbestos

Some of these are avoidable and some aren't. Most are only contributing factors to causing cancers – part of the jigsaw puzzle that scientists are still trying to put together. There is more about this in the page about causes of cancer in the environment.

Viruses can help to cause some cancers. But this does not mean that these cancers can be caught like an infection. What happens is that the virus can cause genetic changes in cells that make them more likely to become cancerous.

These cancers and viruses are linked

Cervical cancer, and other cancers of the genital and anal area, and the human papilloma virus(HPV)
Primary liver cancer and the Hepatitis B and C viruses
Lymphomas and the Epstein-Barr Virus
T cell leukaemia in adults and the Human T cell leukaemia virus
HPV may also lead to oropharyngeal cancer and non melanoma skin cancers in some people

There will be people with primary liver cancer and with T cell leukaemia who haven't had the related virus. But infection increases their risk of getting that particular cancer. With cervical cancer, scientists now believe that every woman with an invasive cervical cancer has had an HPV infectionbeforehand.

Many people can be infected with a cancer causing virus, and never get cancer. The virus only causes cancer in certain situations. Many women get a high risk HPV infection, but never develop cervical cancer.

Another example is Epstein-Barr virus (EBV). These are some facts about EBV

It is very common – most people are infected with EBV
People who catch it late in life get glandular fever and have an increased risk of lymphoma
In sub Saharan Africa, EBV infection and repeated attacks of malaria together cause a cancer called Burkitt's lymphoma in children
In China, EBV infection (together with other unknown factors) causes nasopharyngeal cancer
In people with AIDs and transplant patients EBV can cause lymphoma
About 4 out of 10 cases of Hodgkin's lymphoma (40%) and a quarter of cases (25%) of Burkitt's lymphoma (a rare type of non Hodgkin's lymphoma) seem to be related to EBV infection

Bacterial infections have not been thought of as cancer causing agents in the past. But studies have shown that people who have helicobacter pylori (H pylori) infection of their stomach develop inflammation of the stomach lining, which increases the risk of stomach cancer. Helicobacter pylori infection can be treated with a combination of antibiotics.

Research is also looking at whether substances produced by particular types of bacteria in the digestive system can increase the risk of bowel cancer or stomach lymphomas. Some researchers think that particular bacteria may produce cancer causing substances in some people. But research into this issue is at an early stage.

If bacteria do play a part in causing cancer this could be important in cancer prevention. Bacterial infections can often be cured with antibiotics, so getting rid of the infection could be a way to reduce the risk of these types of cancer.

Cancer Signs and Symptoms

Cancer gives most people no symptoms or signs that exclusively indicate the disease. Unfortunately, every complaint or symptom of cancer can be explained by a harmless condition as well. If certain symptoms occur, however, a doctor should be seen for further evaluation. Some common symptoms that may occur with cancer are as follows:

Persistent cough or blood-tinged saliva
- These symptoms usually represent simple infections such as bronchitis or sinusitis.
- They could be symptoms of cancer of the lung, head, and neck. Anyone with a cough that lasts more than a month or with blood in the mucus that is coughed up should see a doctor.
A change in bowel habits
- Most changes in bowel habits are related to your diet and fluid intake.
- Doctors sometimes see pencil-thin stools with colon cancer.
- Occasionally, cancer exhibits continuous diarrhea.
- Some people with cancer feel as if they need to have a bowel movement and still feel that way after they have had a bowel movement. If any of these abnormal bowel complaints last more than a few days, they require evaluation.
Blood in the stool
- A doctor always should investigate blood in your stool.
- Hemorrhoids frequently cause rectal bleeding, but because hemorrhoids are so common, they may exist with cancer. Therefore, even when you have hemorrhoids, you should have a doctor examine your entire intestinal tract when you have blood in your bowel movements.
- With some individuals, X-ray studies may be enough to clarify a diagnosis.
- Colonoscopy is usually recommended.
- Sometimes when the source of bleeding is entirely clear (for example, recurrent ulcers), these studies may not be needed.
Unexplained anemia
- Anemia is a condition in which people have fewer than the expected number of red blood cells in their blood. Anemia should be investigated.
- There are many kinds of anemia, but blood loss almost always causes iron deficiency anemia. Unless there is an obvious source of ongoing blood loss, this anemia needs to be explained.
- Many cancers can cause anemia, but bowel cancers most commonly cause iron deficiency anemia. Evaluation should include endoscopy or X-ray studies of your upper and lower intestinal tracts.
Breast lump or breast discharge
- Most breast lumps are noncancerous tumors such as fibroadenomas or cysts. But all breast lumps need to be thoroughly investigated.
- A negative mammogram result is not usually sufficient to evaluate a breast lump. Your doctor needs to determine the appropriate X-ray study which might include an MRI or an ultrasound of the breast.
- Generally, diagnosis requires a needle aspiration or biopsy (a small tissue sample).
- Discharge from a breast is common, but some forms of discharge may be signs of cancer. If discharge is bloody or from only one nipple, further evaluation is recommended.
- Women are advised to conduct monthly breast self-examinations.
Lumps in the testicles
- Most men (90%) with cancer of the testicle have a painless or uncomfortable lump on a testicle.
- Some men have an enlarged testicle.
- Other conditions, such as infections and swollen veins, can also cause changes in your testicles, but any lump should be evaluated.
- Men are advised to conduct monthly testicular self-examinations.
A change in urination
- Urinary symptoms can include frequent urination, small amounts of urine, and slow urine flow.
- These symptoms can be caused by urinary infections (usually in women) or, in men, by an enlarged prostate gland.
  - Most men will suffer from harmless prostate enlargement as they age and will often have these urinary symptoms.
  - These symptoms may also signal prostate cancer.
  - Men experiencing urinary symptoms need a bit of investigation, probably including a specific blood test called a PSA and a digital rectal exam.
- If cancer is suspected, a biopsy of the prostate may be needed.
- Cancer of the bladder and pelvic tumors can also cause irritation of the bladder and urinary frequency
  
  More Cancer Signs and Symptoms
  - Blood in the urine
    - Hematuria or blood in the urine can be caused by urinary infection, kidney stones, or other causes.
    - For some people, it is a symptom of cancer of the bladder or kidney.
    - Any episode of blood in the urine should be investigated.
  - Hoarseness
    - Hoarseness not caused by a respiratory infection or that lasts longer than three to four weeks should be evaluated.
    - Hoarseness can be caused by simple allergy or by vocal cord polyps, but it could also be the first sign of cancer of the throat.
  - Persistent lumps or swollen glands
    - Lumps most frequently represent harmless conditions such as a benigncyst. A doctor should examine any new lump or a lump that won't go away.
    - Lumps may represent cancer or a swollen lymph gland related to cancer.
    - Lymph nodes swell from infection and other causes and may take weeks to shrink again.
    - A lump or gland that remains swollen for three to four weeks should be evaluated.
  - Obvious change in a wart or a mole
    - Multicolored moles that have irregular edges or bleed may be cancerous.
    - Larger moles are more worrisome and need to be evaluated, especially if they seem to be enlarging.
    - Removing a mole is usually simple. You should have your doctor evaluate any suspicious mole for removal. The doctor will send it for examination under a microscope for skin cancer.
  - Indigestion or difficulty swallowing
    - Most people with chronic heartburn usually do not have serious problems.
    - People who suffer from chronic or lasting symptoms despite using over-the-counter antacids may need to have an upper GI endoscopy.
    - A condition called Barrett esophagus, which can lead to cancer of the esophagus, can be treated with medication and then monitored by a doctor.
    - Difficulty swallowing is a common problem, especially in elderly people, and has many causes.
      - Swallowing problems need to be investigated, because nutrition is always important.
      - Difficulty swallowing solids can be seen with cancer of the esophagus.
  - Unusual vaginal bleeding or discharge
    - Unusual vaginal bleeding or bloody discharge may be an early sign of cancer of the uterus. Women should be evaluated when they have bleeding after intercourse or bleeding between periods.
    - Bleeding that comes back, that lasts two or more days longer than expected, or that is heavier than usual also merits medical examination.
    - Postmenopausal bleeding, unless expected on hormone therapy, is also worrisome and should be evaluated.
    - Usually, the evaluation will include an endometrial biopsy, in which a doctor takes a small tissue sample from inside the uterus for testing.
    - A PAP smear should be part of a woman's routine medical care.
  - Unexpected weight loss, night sweats, or fever
    - These nonspecific symptoms might be present with several different types of cancer.
    - Various infections can lead to similar symptoms (for example,tuberculosis).
  - Continued itching in the anal or genital area
    - Precancerous or cancerous conditions of the skin of the genital or anal areas can cause persistent itching.
    - Some cancers cause skin color changes.
    - Several infections or skin conditions (for example, fungal infections orpsoriasis) also can cause these symptoms. If itching does not stop with over-the-counter topical medications, your doctor should inspect the area.
  - Nonhealing sores
    - Sores generally heal quickly. If an area fails to heal, you may have cancer and should see a doctor.
    - Nonhealing sores in your mouth or persistent white or red patches on your gums, tongue, or tonsils are also should raise concerns.
    - Some nonhealing sores may be due to poor circulation (for example, diabetic foot ulcers).
  - Headaches
    - Headaches have many causes (for example, migraines, aneurysms) but cancer is not a common one.
    - A severe unrelenting headache that feels different from usual can be a sign of cancer, but aneurysms may present in the same way.
    - If your headache fails to improve with over-the-counter medications, see a doctor promptly.
  - Back pain, pelvic pain, bloating, or indigestion
    - These are common symptoms of daily life, often related to food intake, muscle spasms or strains, but they also can be seen in ovarian cancer.
    - Ovarian cancer is particularly difficult to treat, because it is frequently diagnosed late in the course of the disease.

TECHNOPHILIA

Saturday, 21 February 2015