Introduction and Conclusion to Cancer

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1.What Is Cancer?
CANCER, a 6 letter word that makes our world upside down.
Cancer is not just one disease, but a large group of almost 100 diseases. Its two main characteristics are uncontrolled growth of the cells in the human body and the ability of these cells to migrate from the original site and spread to distant sites. If the spread is not controlled, cancer can result in death. 2.How does cancer occur?

The body is made up of trillions of living cells. These cells grow, divide, and die in an orderly fashion. This process is a tightly regulated one that is controlled by the DNA machinery within the cell. When a person is a baby or a child or within his or her mother’s womb, cells divide rapidly to allow for growth. After the person becomes an adult, most cells divide only to replace worn-out or dying cells or to repair injuries. When cells of the body at a particular site start to grow out of control, they may become cancerous. Cancer cell growth is different from normal cell growth. Instead of dying, cancer cells continue to grow and form new, abnormal cells. In addition, these cells can also invade other tissues. This is a property that normal cells do not possess. 3.Molecular pathology behind cancer

Cancer cells originate from normal cells when their DNA (deoxyribonucleic acid) or blue prints within the cell nucleus is damaged. DNA is in every cell and it directs all the cell’s actions, growth, death, protein synthesis etc. When DNA is damaged in a normal cell, the cell either repairs the damage or the cell dies. In cancer cells, the damaged DNA is not repaired, and the cell does not die. Instead it gives rise to more such abnormal cells with abnormal DNA. These new cells all have the same defective DNA of the original cancer cell. DNA damage may be inherited from parents or may be a spontaneous problem that occurs during the lifetime of a person. DNA damage may also be triggered by exposure to certain environmental toxins such as those present in cigarette smoke. There are, however, multiple factors that may cause cancer and it is difficult to pin point an exact cause.

4.Cancerous and benign tumors
As the cells proliferate they may form tumors. Not all of these tumors are cancerous. Those that are not cancerous are called benign tumors. And those that are, are called malignant tumors. Benign tumors can grow very large and press on healthy organs and tissues. However, they do not invade other organs or spread via blood or lymphatic channels. These tumors are almost never life threatening. * How are Malignant and Benign Tumors Similar?

Some similarities include:
* Both can grow quite large. Size alone does not make the distinction between these types of tumors. In fact, benign ovarian tumors weighing over a hundred pounds have been removed. * Both can be dangerous at times. While benign tumors tend to be more of a nuisance, they can, in some cases, be life threatening. An example is benign brain tumors. When these tumors grow in the enclosed space of the brain, they can put pressure on, and destroy other brain structures, resulting in paralysis, speech problems, seizures, and even death. Some benign tumors, such as pheochromocytomas, secrete hormones that can cause life-threatening symptoms as well. * Both can recur locally. If cells are left over after surgery, both benign and malignant tumors may later recur near the region of the original tumor.

Differences Between Benign and Malignant Tumors
* Rate of growth - In general, malignant tumors grow much more rapidly than benign tumors, but there are exceptions. Some malignant (cancerous) tumors grow very slowly, while some benign tumors grow rapidly. * Ability to metastasize - Benign tumors expand locally, whereas malignant tumors can spread (metastasize) to other parts of the body by way of the bloodstream and lymphatic channels. * Site of recurrence - While benign tumors may recur locally — that is, near the site of the original...
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