About colon and rectal cancer
Colon and rectal cancer refers to the malignancy of the large
intestine which constitutes of the ascending colon, the transverse
colon, the descending colon and the rectum. The colon is primarily
responsible for absorbing excess water from the nearly digested food
which has been passed along from the small intestine and converting them
into faeces which get stored in the rectum before being passed into
anal canal during bowel movement.
The cancer (abnormal growth of cells) in the large intestine usually
develops in the glandular tissue. The cancer of colon and rectum
generally exhibit similar characteristics and behaviour with only a
minor difference in their steps of management.
Colon and rectal cancer: Incidence, age and sex
Colon and rectal cancer are commonly encountered malignant conditions
in the developed world. . They are slightly more frequent in men as
compared with women. Individuals of more than 50 years of age are more
susceptible, though it may occur in any age group. The cancer of the
colon is more prevalent than rectal cancer.
Signs and symptoms of colon and rectal cancer: Diagnosis
The clinical features are usually absent or minimal during the early
stage of cancer. However as the cancer progresses, the affected
individual may present with complains of flatulence and abdominal pain
which may be vague or cramping in quality. Cancer of the rectum may also
manifest with left lower abdominal pain during bowel movement. Stool
disorders like blood and mucous stained faeces or feeling of incomplete
evacuation may also be complained of. Any recent change in bowel habit
or alternating occurrence of constipation and diarrhoea is quite
characteristic of large bowel cancer. Other features include loss of
appetite, weight loss and anaemia.
Such features need to be evaluated comprehensively by a
gastroenterologist who may conduct investigations like proctoscopy and
colonoscopy which help in direct visualization of inside of large bowel.
Other tests like faecal occult blood test, biopsy and direct rectal
examination may aid in establishing the diagnosis. The cancer in later
stages may spread to other organs like the liver and the lungs which may
be detected by CT scans of the chest and the abdomen.
Causes and prevention of colon and rectal cancer
Cancer of colon and rectum may be caused in individuals who have
genetic disorders like ‘familial adenomatous polyposis’ and ‘hereditary
non-polyposis cancer of colon’. Such conditions are hereditary and
characterised by abnormal growth in the lining of wall of the large
bowel which may later develop into cancerous growths. Inflammatory bowel
diseases like ulcerative colitis and crohn’s disease damage the large
bowel and increase the likelihood of cancer. Certain risk factors like
excess alcohol consumption, smoking, obesity and low fibre content in
diet may also predispose people to this cancer.
Colon and rectal cancer: Complications
Cancer of colon and rectum may spread to other organs like the liver
and the lungs through the bloodstream and the lymphatic route.
Colon and rectal cancer: Treatment
The management of colon and rectal cancer depends on the site,
severity and spread of the cancer. The primary treatment modality is
surgical resection of the cancerous part of bowel followed by end to end
suturing. The treatment of choice in the cancer of the colon is
surgical resection followed by chemotherapy with 5-fluorouracil whereas
cancer of the rectum is mostly managed by surgical resection followed by
radiotherapy. In instances of spread of cancer to other organs, all the
three modalities may be considered which may vary from individual to
individual. The prognosis of colon and rectal cancer is good if the
cancer is diagnosed in the early stages.