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Cancer of the colon and rectum is currently the second most common cause of
cancer death in USA. When it is possible to perform a curative resection, 66% of
patients survive 5 years and are considered as cured. The overall outcome after
surgery is largely dependent on the tumor stage at the time of presentation.
Symptoms of colorectal cancer
Most commonly, patients have no symptoms, however a variety of
symptoms may develop as tumors continue to progress, including:
- A change in bowel habit (diarrhea or constipation)
- Weight loss and tiredness
- Blood in the stool or anemia
- Narrow stools, incomplete evacuation
- Vomiting, cramps, abdominal bloating
Investigation and diagnosis
First, the doctor reviews the patient's medical history, symptoms,
family history and then performs a physical examination. Other tests are ordered
when indicated, including:
- Examination of the bowel by colonoscopy and/or proctoscopy. For these test
the bowel is cleaned with a solution, and a lighted (usually flexible)
instrument is used to check the lining of the bowel. Samples can be taken as
needed.
- Barium enema. A similar type of bowel check by X-ray. No sampling
possible.
Mechanisms of spread and treatment protocols
Treatment is based on our current understanding of the ways
colorectal cancer progresses. These cancers spread by local direct invasion in
the tissues surrounding the place where the tumor starts. As the tumor
progresses, it can spread along lymph channels to the local lymph nodes (or
glands). Finally, the tumor can spread by blood, usually to the liver.
Tests are performed before the operation to develop the best treatment
strategy for the individual patient. This is particularly important for cancer
of the rectum. Ultrasound of the rectum and computerized tomography (CT scans)
may be used to see how advanced the tumor is. While surgery is the key to curing
these cancers, the more advanced tumors are treated before surgery with
combinations of chemotherapy (anti-cancer drugs) and radiotherapy (X- ray
treatment) to shrink the cancer. These agents help to prevent the cancer coming
back.
Preparation for surgery
The surgeon will explain the type of surgery that is best for any
particular tumor, and explain the likely outcome of such treatment. If the
patient has other illnesses, these may need some attention before undergoing
surgery. The day before surgery the patient drinks a solution to clear the
bowel, and the morning of surgery he or she is given drugs to reduce the chance
of infections or deep vein clots after surgery.
A section of the colon is then removed which contains the tumor. With this
section of colon are removed the draining lymph nodes and blood vessels to
minimize the chance of leaving tumor behind. Pieces of adjacent organs are
sometimes removed with the tumor specimen to get rid of all tumor.
The bowel ends are then stitched or stapled together in most circumstances.
When this is particularly difficult, a temporary stoma (where the bowel is
brought out onto the skin to drain the bowel content into a bag) may be placed
for about three months to protect the anastomosis (joining in the bowel).
Rarely, when the tumor is extremely close to the anus, and may involve the
muscles giving control over stool, it is necessary to give the patient a
permanent colostomy.
Laparoscopic surgery. Laparoscopy (keyhole surgery) can be used to
remove colon and rectal cancers. Compared with traditional, open surgery,
patients spend about half the amount of time in the hospital and have a shorter
recovery period. Recent trials confirm the good cancer outcomes and improved
recovery of laparoscopic surgery.
Pathological staging and outcome
After the bowel containing the tumor is removed, it is examined by
the pathologist under a microscope. The pathological stage of the tumor gives an
approximate guide to outcome after surgery. Early tumors which have not breached
the muscle wall are cured in approximately 85% of cases. Those which are into or
breach muscle are cured in 60% of cases. When there are lymph glands involved,
survival drops to about 30% at 5 years.
Postoperative treatment
Patients with more advanced disease tend to need further treatment
after surgery. This usually involves chemotherapy (drug therapy) and can
continue for a period of six months after the time of surgery. This is generally
reserved for patients with lymph nodes involved by tumor, but may be selectively
given to patients whose tumors have breached the muscular wall of the bowel.
Follow-up after surgery
After undergoing this type of major surgery, patients are usually
seen every 3 months for the first two years, and then every six months for the
next three years. During this time, patients undergo regular physical
examination, and often need regular blood testing for CEA (a blood test which
can mark cancer recurrence in some patients). Patients also need regular
colonoscopy at 1 to 3 year intervals to pick up further polyps, or the
development of new cancers.
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