CAUSES OF CANCER

Cancer can develop in the human body, where this discussion has been detailed in previous posts. In this article will discuss about the things that cause cancer.

Scientists do not fully understand the causes of cancer, but studies show that some people are more likely to develop the disease than others. Scientists called epidemiologists study particular populations to identify why cancer rates vary. One method they use is to compare cancer patients with healthy people in terms of behavior such as diet, exercise, and smoking and traits such as gender, age, and race. Population studies provide useful information about risk factors that increase the likelihood of developing cancer.

1. Carcinogens

One of the greatest risk factors for cancer is prolonged or repeated exposure to carcinogens—chemical, biological, or physical agents that cause the cellular damage that leads to cancer. The details of how carcinogens cause cancer remain unclear. One theory is that exposure to carcinogens, when combined with the effects of aging, causes an increase in chemicals in the body called free radicals. An excessive number of free radicals causes damage by taking negatively charged particles called electrons from key cellular components of the body, such as DNA. This may make genes more vulnerable to the mutating effects of carcinogens.

2. Hereditary Factors

Evidence suggests that heredity plays a role in developing cancer. Some gene mutations associated with cancer are inherited. For example, inheriting mutated tumor suppressor genes BRCA1 or BRCA2 greatly increases a woman’s chances of developing breast cancer. About 50 to 60 percent of women with inherited BRCA1 or BRCA2 mutations will develop breast cancer by the age of 70. Inherited mutations in the genes MSH2, MLH1, PMS1, and PMS2, all of which repair DNA, are especially prevalent in a rare form of hereditary colon cancer.

Scientists suspect that many other hereditary factors contribute to cancer. In addition to inherited mutations, other genetic variations, particularly those influencing how the body responds to carcinogens, may create a greater susceptibility to cancer. The identities of the majority of these genetic variations are not yet known.

3. Steroid Hormones

Medical research suggests that cancers of the reproductive organs may be affected by naturally occurring steroid hormones produced by the endocrine system. These hormones stimulate reproductive organ cells to divide and grow. In women, relatively high or long exposure to the female sex hormone estrogen seems to increase the risk of breast and uterine cancers.

Thus, early age at first menstruation, late age at menopause, having a first child after age 30, and never having children, all of which affect the duration of estrogen exposure in the body, increase the risk for these cancers. Studies also indicate that hormone replacement therapy (HRT), in which women take estrogen to offset the unpleasant effects of menopause, increases the risk of breast cancer. Male sex hormones, particularly testosterone, appear to play a role in cancers of the male reproductive organs, but this role is not yet well understood.

4. Population Demographics

Population studies show that a person’s age, race, and gender affect the probability that he or she will develop cancer. Most cancers occur in adults middle-aged or older. The risk of cancer increases as individuals age because genetic mutations accumulate slowly over many years, and the older a person is, the more likely that he or she will have accumulated the collection of mutations necessary to turn an otherwise healthy cell into a cancerous cell.

More than three-fourths of all cancers in North America are diagnosed in people over age 55. Statistics show that men are more likely to develop cancer than women. In the United States, nearly half of all men will develop cancer at some point in their lifetimes, whereas slightly more than one-third of women will.

Stomach cancer is nearly twice as common in men as in women, as are certain types of kidney cancer. However, the reasons for the discrepancy between the sexes are unknown. Some cancers are more prevalent in particular races than others. In the United States, for example, bladder cancer is twice as common in white people as in black people. White women are slightly more likely to develop breast cancer than are black women, but black women are more likely to die of the disease.

Asian, Hispanic, and Native American women have the lowest breast cancer risk. On the whole, African Americans, especially men, are more likely to develop cancer—and more likely to die from it—than members of any other group in the United States. Reasons for the discrepancies between races are still not entirely clear, but many epidemiologists trace them to differences in diet and exercise, unequal access to medical care, and exposure to carcinogens.

HOW CAN CANCER DEVELOP IN OUR BODY: CELLS BREAK FREE AND SPREAD

More cancer, more cancer again, the reader may get bored with this article, but this information must I provide to be a lesson for us. Cancer can develop in the human body, therefore I think we need to know how the cancer can develop in the body. This article is a continuation of previous articles that discuss the same topic. Evading the many obstacles that guard against runaway cell division is still not enough for cancer to develop. A malfunctioning cell must also skirt a number of safety mechanisms designed to prevent cells from growing where they are not supposed to in the body.

Normal cells adhere to each other and to a fibrous meshwork called an extracellular matrix. This matrix exists throughout all tissues and provides the structural support on which cells grow and form organs and other complex tissues. While a normal cell will often die if it cannot adhere to an extracellular matrix, cancer cells survive without this matrix.

1. Tumor Forms

A tumor is a mass of cells not dependent upon an extracellular matrix. These cells can grow on top of each other, creating a mass of abnormal cells. Often a tumor develops its own network of tiny blood vessels to supply itself with nutrient-rich blood, a process called angiogenesis.

There are two general types of tumors. Benign tumors do not invade other tissues and are limited to one site, making surgical removal possible and the odds for a full recovery excellent. Some benign tumors are quite harmless and are not surgically removed unless they are unsightly or uncomfortable. For example, warts are benign tumors of the outer layer of the skin. Although they are usually not dangerous, warts may cause discomfort. Other benign tumors are thought to be precursors to cancerous, or malignant, tumors.

2. Tumors Spread

Tumors are malignant only if they can invade other parts of the body. Malignant tumors extend into neighboring tissue or travel to distant sites, forming secondary growths known as metastases. To metastasize, tumor cells break through a nearby blood vessel to enter the circulatory system or through a lymphatic vessel wall to enter the lymphatic system. Most metastases occur in organs that are the next site downstream in the circulatory system or the lymphatic system and contain a network of capillaries, or small blood vessels. For example, cancer of the large intestine often travels through the bloodstream to the liver, the organ immediately downstream from the intestines.
In the lymphatic system, tumor cells can spread to surrounding lymph nodes, or lymph glands. Normally, lymph nodes filter out and destroy infectious materials circulating in the lymphatic system.
The unique receptors on the surface of a cell may also play a role in where tumors metastasize. Specialized molecules on a cell’s surface identify where in the body the cell belongs. Similar cells adhere to one another when their surface receptors are compatible. Most often cells from different tissues and organs have incompatible surface receptors.

However, some tissue types share similar surface receptors, enabling cancerous cells to move between them and proliferate. Prostate cells and bone cells, for example, have similar surface receptors. This gives prostate cancer cells a natural affinity for bone tissue, where they can settle to form a new tumor.

Many cancers shed cells into the bloodstream early in their growth. Most of these cells die in the bloodstream, but some lodge against the surface of the blood vessel walls, eventually breaking through them and into adjacent tissue.

In some cases, these cells survive and grow into a tumor. Others may divide only a few times, forming a small nest of cells that remain dormant as a micrometastasis. They may remain dormant for many years, only to grow again for reasons not yet known.

HOW CAN CANCER DEVELOP IN OUR BODY: BODY SECURITY SYSTEM FAILED

Some time ago I wrote an article about how cancer develops?now I'll write a continuation of the article, how the cancer can develop in our body. While each human cell performs its own specialized function, it also exerts influence on the cells around it. Cells communicate with one another via receptors, protein molecules on the cell surface. A cell releases chemical messages, which fit into the surface receptors of cells nearby, much as a key fits into a lock. A cell may instruct other cells in its neighborhood to divide, for example, by releasing a growth-promoting signal, or growth factor.

The growth factor binds to receptors on adjacent cells, activating a message within each individual cell. This message travels to the nucleus, where a cell’s genes are located.

1. Proto-Oncogenes Become Oncogenes

When the growth factor message reaches the cell nucleus, it activates genes called proto-oncogenes. These genes produce proteins that stimulate the cell to divide. In cancerous cells, mutations in proto-oncogenes cause these genes to malfunction.

When a proto-oncogene mutates, it becomes an oncogene—a gene that instructs the cell to grow nd divide repeatedly without stimulation from neighboring cells. Some oncogenes overproduce growth factors, causing the cell to divide too often.

Other oncogenes stimulate the cell to reproduce even when no growth factor is present. Cancer researchers have identified about 100 different types of proto-oncogenes and their cancer-causing oncogene counterparts.

2. Tumor Suppressor Genes Stop Working

When runaway cell division occurs, it does not necessarily lead to cancer. Neighboring cells respond by excreting a growth inhibitor. This chemical binds to receptors in the malfunctioning cell, sending a signal to the nucleus that activates tumor suppressor genes. Tumor suppressor genes are like brakes for cell growth.

When activated, these genes halt the cell cycle, preventing further cell division. But if tumor suppressor genes malfunction due to mutations, the rapidly dividing cell ignores messages from its neighbors telling it to stop dividing. Malfunctioning tumor suppressor genes are not enough to cause cancer—the cell still must overcome a host of other safety mechanisms before it can cause truly significant damage.

3. Cell Cycle Clock Malfunctions

The cell nucleus contains a collection of interacting proteins that control cell division. Sometimes called the cell cycle clock, this group of proteins interprets incoming messages at several checkpoints in the cell division cycle.
At these checkpoints, the clock evaluates the health of the cell. If conditions are right, the clock activates certain proto-oncogenes, which produce proteins that trigger the cell to enter the next stage of the cell cycle. If conditions are not right, certain tumor suppressor genes produce proteins that prevent the cell from proceeding with cell division.

HOW CANCER DEVELOPS

Some time ago I wrote about what it was cancer, well now who will write about how the cancer could develop in the human body, so that we can take advantage to be able to avoid cancer.

A healthy human body is composed of 30 trillion cells, most of which are in constant turnover as cells die and others reproduce to replace them in an orderly fashion. Healthy cells of the skin, hair, lining of the stomach, and blood, for example, regularly reproduce by dividing to form two daughter cells.

This cell division cycle proceeds under the regulation of the body’s intricately tuned control system. Among other functions, this control system ensures that cells only divide when needed, so that organs and tissues maintain their correct shape and size. Should this system fail, a variety of backup safety mechanisms prevent the cell from dividing uncontrollably. In order for a cell to become cancerous, every one of these safety mechanisms must fail.

Cancer begins in genes, bits of biochemical instructions composed of individual segments of the long, coiled molecule deoxyribonucleic acid (DNA). Genes contain the instructions to make proteins, molecular laborers that serve as building blocks of cells, control chemical reactions, or transport materials to and from cells.

The proteins produced in a human cell determine the function of each cell, and ultimately, the function of the entire body. In a cancerous cell, permanent gene alterations, or mutations, cause the cell to malfunction. For a cell to become cancerous, usually three to seven different mutations must occur in a single cell. These genetic mutations may take many years to accumulate, but the convergence of mutations enables the cell to become cancerous.

CANCER

Introduction

Cancer , any of more than 100 diseases characterized by excessive, uncontrolled growth of abnormal cells, which invade and destroy other tissues. Cancer develops in almost any organ or tissue of the body, but certain types of cancer are more life-threatening than others. In the United States and Canada cancer ranks as the second leading cause of death, exceeded only by heart disease.

For reasons not well understood, cancer rates vary by gender, race, and geographic region. For instance, more men than women develop cancer, and African Americans are more likely to develop cancer than people of any other racial group in North America. The frequency of certain cancers also varies globally. For example, breast cancer is more common in wealthy countries, and cervical cancer is more common in poor countries.
Although people of all ages develop cancer, most types of cancer are more common in people over the age of 50.
Cancer usually develops gradually over many years, the result of a complex mix of environmental, nutritional, behavioral, and hereditary factors. Scientists do not completely understand the causes of cancer, but they know that certain lifestyle choices can reduce the risk of developing many types of cancer. Not smoking, eating a healthy diet, and exercising moderately for at least 30 minutes each day can lower the likelihood of developing cancer.

Just 60 years ago a cancer diagnosis carried little hope for survival because doctors understood little about the disease and how to control it. Today about two-thirds of all Americans diagnosed with cancer live longer than five years. While it is difficult to claim that a cancer patient is disease free, long-term survival significantly improves if the patient has had no recurrence of the cancer for five years after the initial diagnosis. For years, death rates from cancer were rising in developing countries. In 2006 the American Cancer Society reported that the number of cancer deaths in the United States dropped for two years in a row. The decrease was attributed to a decline in smoking, earlier detection, and improved treatment.

THALASSEMIA

Thalassemia

Leukemia

Leukemia

LEUKEMIA

Know the Early Symptoms of Leukemia

Leukemia destroy white blood cells or in the language of medicine called a white blood cell (WBC). With early recognition and treatment, the chance to recover from this disease will be better. The following are early symptoms of leukemia you need to know:

1. You often feel tired? Leukemia can cause you to tire easily, because of the increased production of white blood cells resulted in a large energy absorption of the body.

2. Is your weight continues to decrease? Would you eat a portion as usual, but your clothes getting loose? Leukemia causes reduced body weight, due to increased production of white blood cells to absorb many calories your body.

3. Record the frequency of headaches and feeling / dizziness and sometimes led to confusion. Increased production of white blood cells that normally do not penetrate into the possibility of central nervous system.

4th. Does your child often bleeding, nosebleeds, or appear bruised in several parts of her body? This is a common symptom of leukemia in children. Besides the red spots appear on the body, which is a common symptom of leukemia other children, is associated with swelling of the spleen and liver.

5. Check your type of paleness. Is your brightness and your face began redum kebinaran? This is also a common symptom of leukemia. Increased production of white blood cells that are not normally possible 'urgent' your red blood cells, thus making you be like less blood.

6. Check your lymph glands. Feel something under your armpits or on your throat. Do you feel a lump or swelling in there kind? Swollen lymph nodes are symptoms of leukemia symptoms

7. Try to feel and remember if you ever find a mild infection but did not get well? Even though your body continues to produce white blood cells, as anti body and your body against infection., But the white blood cells produced from the leukemia-affected person's body is not perfect and can not protect your body.

8. Check your spleen in a way: you lie in bed, place your palms on the left abdomen, below the rib cage. Feel if there is a small bump-bump there. This includes symptoms of leukemia.

9. Feel, do you often accompanied by night sweats and abdominal pain in the bones nausea / bloating. Waspadilah, karenatanda these signs are symptoms of leukemia.