cancer is rare in young people. Fewer than 6 percent of cases occur
before the age of 50 years old. Incidences increase markedly after
the age of 50, continues to rise until the age of 75, and then tapers
off. The average age at the time of diagnosis is 60 years old. The
causes of colorectal cancer include:
-Genetic defects on chromosomes 2, 5, 17, and 18
-Family history of colon cancer related to genetic syndromes, such
as HNPCC (Hereditary nonpolyposis colorectal cancer) syndrome of familial
adenomatous polyposis (FAP). Both are rare diseases.
-Eating a high-fat, low-fiber/calcium diet
-Lack of exercise
Some people are more at risk for developing colorectal cancer. The
risk factors include:
-Being over 50 years of age
-Family history of colorectal cancer
-Evidence of or previous polyps in the colon and rectum
-Having FAP or HNPCC
-Having inflammatory bowel disease, such as ulcerative colitis (inflammation
of the colon lining) or Crohn's disease (an ulcerative condition of
the small and large bowels) -
-Eating diets high in fat and low in fiber and calcium .
of Colorectal Cancer are
-Diarrhea or constipation
-Change in bowel habits
-Blood in or on the stool (either bright red or very dark in color)
-General stomach discomfort (bloating, fullness, and/or cramps)
-Frequent gas pains
-Feeling that the bowel does not empty completely
-Weight loss with no known reason
antigen (CEA) is an antigen (protein) present in very small quantities
in adult tissue.
than normal amount may be suggestive of cancer. Normally, its values
range from 0.0 to 2.5 nanograms per milliliter of serum (from blood),
are higher, on average, in men, smokers, and older individuals.
for its presence aid in screening, in evaluating recurrent or disseminated
disease, and in gauging the success of surgical removal of malignant
a substance normally found in a fetus which, when found at elevated
levels in the blood of adults, may indicate the presence of colorectal
cancer or other types of cancer. CEA is therefore called a tumor marker.
been used to monitor patients for the recurrence of a number of different
cancers, including breast, thyroid, lung, ovarian, pancreatic, stomach,
also referred to as an "oncofetal antigen" because of its
similarity to fetal tissue. CEA levels can also be an indication of
the effectiveness of treatment.
of colorectal cancer is associated with multiple tumor suppressor
gene defects but inhibition of tumorigenicity is accomplished by correction
of any single defect via chromosome transfer.
cancer has been associated with the activation of ras oncogenes and
with the deletion of multiple chromosomal regions including chromosomes
5q, 17p, and 18q.
chromosome loss is often suggestive of the deletion or loss of function
of tumor suppressor genes.
defects in tumor suppressor genes seem to be required for progression
to the malignant state in colorectal cancer,