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Colon cancer is the second most frequently diagnosed cancer
in the United States. It is estimated that approximately 100,000 cases
of colon cancer are diagnosed each year. There are half that many colon
cancer patient deaths reported each year, giving colon cancer the second
highest mortality rate for cancer in the US (Ref.
16). It also is one of the most common inherited cancers known
(Ref. 12). Hereditary Non-Polyposis Colon
Cancer accounts for approximately 6% of these cases. The diagnosis of this
disease is tricky since there is no morphological difference to separate
HNPCC from sporadic colon cancer cases. Therefore, diagnosis is dependent
on a pedigree and there is a wide spectrum of mutations involved, including
4 different genes that have been identified. (Ref.
17)
The variety of mutations have led HNPCC to be further
separated into two syndromes. Lynch I (colon specific cancer) involves
only cancer of the colon and the rectum, predominately on the right
side. Lynch II (non-colon specific) involves cancer of the colon and/or
several other tissues including the lining of the uterus, the ovary, the
small bowel, ureters, bladder, and renal pelvis of the kidney.
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