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Cancer
Cancer starts
when abnormal cells begin dividing uncontrollably, eventually forming a visible
mass also known as a tumor (1). The
abnormal cancerous cells do not follow the normal path of growing, dividing,
and dying in an orderly fashion (2).
Normal cells divide to replace dying or injured cells; however,
cancerous cells outlive normal cells and continue to grow and divide at an
accelerated rate, forming new abnormal cells (2). Cancer cells develop due to damage to their
DNA, a substance which resides in every cell and directs all of its activities
(2). Different forms of cancer require
different forms of specialized treatment.
To determine what type of cancer is occurring it is best to detect what
organ the cancer started in, the kind of cell the cancer derived from, and the
appearance of the affected cancerous cells (1).
The
process of cancer spreading throughout the body is called metastasis. Cancer cells are able to easily spread by
entering the bloodstream or lymph vessels of the body (2). The initial mass of abnormal, cancerous cells
is known as the primary tumor; secondary tumors form when cells from the
primary tumor break off and become lodged in other parts of the body,
eventually forming their own masses (1).
When cancer becomes metastatic the type of cancer remains the type of
the primary tumor (1). Several different
types of cancer can start in the same organ (1).
It
is common for cancer to return even after the primary tumor has been removed
due to cancerous cells that had already broken away from the primary tumor, or
metastasized, and lodged in distant locations but had not formed tumors which
were large enough to detect at the time of removal (1). Cancer that occurs when the entire visible
tumor has been removed is called recurrent disease (1). Cancer that returns in the area of the
primary tumor is called locally recurrent disease, while cancer that returns in
a metastasized form is referred to as distance recurrence (1). Not all tumors are cancerous, such as benign,
or non-cancerous, tumors that do not metastasize and are rarely life
threatening (2). Sarcomas are cancers of
the connective tissue, cartilage, bone, muscle, and other locations (1). Carcinomas are cancers of the epithelial or
lining cells (1). Adenocarcinomas are
carcinomas that begin from a glandular origin (1).
1) www.cancerguide.org/basic.html
2) www.cancer.org/docroot/cricontent/cri_2_6x_the_history_of_cancer_72.asp?sitear…
Home Mitosis Meiosis
P53 Apoptosis Cancer History of Cancer
Treatments Transgenic Mice
Dox Treatment
Future
of Dox Credits