Cancer

INTRODUCTION

Cancer is a disease in which some of the body’s cells grow uncontrollably and spread to other parts of the body. 

Cancer can start almost anywhere in the human body, which is made up of trillions of cells. Normally, human cells grow and multiply (through a process called cell division) to form new cells as the body needs them. When cells grow old or become damaged, they die, and new cells take their place.

Sometimes this orderly process breaks down, and abnormal or damaged cells grow and multiply when they shouldn’t. These cells may form tumors, which are lumps of tissue. Tumors can be cancerous or not cancerous (benign). 

Differences between Cancer Cells and Normal Cell

Cancer cells differ from normal cells in many ways. For instance, cancer cells:

• grow in the absence of signals telling them to grow. Normal cells only grow when they receive such signals. 
• ignore signals that normally tell cells to stop dividing or to die (a process known, programmed cell death or apoptosis).
• invade into nearby areas and spread to other areas of the body. Normal cells stop growing when they encounter other cells, and most normal cells do not move around the body. 
• tell blood vessels to grow toward tumors.  These blood vessels supply tumors with oxygen and nutrients and remove waste products from tumors

• How Does Cancer Develop?

  Cancer is a genetic disease—that is, it is caused by changes to genes that control the way our cell's function, especially how they grow and divide.

  Genetic changes that cause cancer can happen because:

  • of errors that occur as cells divide. 
  • of damage to DNA caused by harmful substances in the environment, such as the chemicals in tobacco smoke and ultraviolet rays from the sun. (Our Cancer causes and prevention)
  • they were inherited from our parents.  

  The body normally eliminates cells with damaged DNA before they turn cancerous. But the body’s ability to do so goes down as we age. This is part of the reason why there is a higher risk of cancer later in life.

  Each person’s cancer has a unique combination of genetic changes. As the cancer continues to grow, additional changes will occur. Even within the same tumor, different cells may have different genetic changes.

  Types of Cancer

• Carcinoma

  Carcinomas are the most common type of cancer. They are formed by epithelial cells, which are the cells that cover the inside and outside surfaces of the body.

• Sarcoma

  Sarcomas are cancers that form in bone and soft tissues, including muscle, fat, blood vessels, lymph vessels, and fibrous tissue (such as tendons and ligaments).

• Leukemia

  Cancers that begin in the blood-forming tissue of the bone marrow are called leukemias. These cancers do not form solid tumors.

• Lymphoma

  Lymphoma is cancer that begins in lymphocytes (T cells or B cells). These are disease-fighting white blood cells that are part of the immune system. 

• Multiple Myeloma

  Multiple myeloma is cancer that begins in plasma cells, other type of immune cell. The abnormal plasma cells, called myeloma cells, build up in the bone marrow and form tumors in bones all through the body. 

• Melanoma

  Melanoma is cancer that begins in cells that become melanocytes, which are specialized cells that make melanin (the pigment that gives skin its color).

• CONCLUSION

• Cancer has a major impact on society in the United States and across the world. Cancer statistics describe what happens in large groups of people and provide a picture in time of the burden of cancer on society.

  Statistics tell us things such as how many people are diagnosed with and die from cancer each year, the number of people who are currently living after a cancer diagnosis, the average age at diagnosis, and the numbers of people who are still alive at a given time after diagnosis. 

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