The Invader






By Ifeyinwa Ugo-Amadi





The body is made up of numerous cells. These cells make up tissues which make up organs. In turn, organs make up the ten systems of the body. Normally, these cells grow, divide to make new cells and die in an organized manner. At childhood and teen years, normal cells divide at a fast rate allowing the person to grow. As one becomes an adult, the cells divide just to replace dead or worn out cells or to repair injuries.

When something goes wrong and these normal cells start to grow out of control - cancer is suspected. Cancer is a term used to describe a set of diseases in which abnormal cells divide without control and can invade other tissues through the blood and lymph system. This process of spreading to other body parts is known as metastasis.

Cancers are named based on the tissue or organ from which they originated. There are over 200 types of cancers with about 20 of them being very common.  According to the Centre for Disease Control, Prostate cancer is the most common cancer among men, breast cancer is most common among women with lung cancer and colorectal cancer being common to both sexes. Common amongst children are leukemia and brain cancer. Others are endometrial, bladder, thyroid, kidney, pancreatic, non-hodgkin lymphoma and melanoma cancers.

In cancer, cells refuse to die due to a change or damage in the genetic material (DNA). These cells grow continuously, forming abnormal cells. Some cancer cells form a mass of tissues known as tumours that could press hard on other organs, pushing them aside and replacing them. Cancers such as leukemia does not form tumours. Tumours can either be benign or malignant.

Benign tumours are not invasive and do not metastasize. They can slowly grow very large pressing hard on other tissues but are rarely life-threatening. This is unlike malignant tumours which are invasive and could spread to other tissues of the body. Though cells like granulocytes, osteoclasts and trophoblastic cells have the ability to invade other cells, the invasive growth of malignant cells is progressive and continuous leading to the destruction of the host tissue. Cells turn out malignant when they are not recognised by the immune’s natural killer cells for destruction.

 Cancer cells are known for some unique features. These include

·         Evasion of a process of programmed cell death

·         Insensitivity to anti-growth signals

·         Self-sufficiency in growth signalling

·         Sustainment of a physiological process through which new blood vessels form from pre-existing ones

·         Activation of metastasis

·         Loss of differentiation



References



http://en.wikipedia.org/wiki/Cancer#Metastasis_2



http://www.cdc.gov/cancer/dcpc/data
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