Colon Cancer (cont.)
What are the treatments and survival for colon
cancer?
Surgery is the most common treatment for colorectal
cancer. During surgery, the tumor, a small margin of the surrounding
healthy bowel, and adjacent lymph nodes are removed. The surgeon
then reconnects the healthy sections of the bowel. In patients
with rectal cancer, the rectum is permanently removed. The surgeon
then creates an opening (colostomy) on the abdomen wall through
which solid waste in the colon is excreted. Specially trained
nurses (enterostomal therapists) can help patients adjust to
colostomies, and most patients with colostomies return to a normal lifestyle.
The long-term prognosis after surgery depends on
whether the cancer has spread to other organs (metastasis). The
risk of metastasis is proportional to the depth of penetration
of the cancer into the bowel wall. In patients with early colon
cancer which is limited to the superficial layer of the bowel
wall, surgery is often the only treatment needed. These patients
can experience long-term survival in excess of 80%.
In patients with advanced colon cancer, wherein the tumor has
penetrated beyond the bowel wall and there is evidence of metastasis
to distant organs, the five-year survival rate is less than 10%.
In some patients, there is no evidence of distant
metastasis at the time of surgery, but the cancer has penetrated
deeply into the colon wall or reached adjacent lymph nodes. These
patients are at risk of tumor recurrence either locally or in
distant organs. Chemotherapy in these patients may delay tumor
recurrence and improve survival.
Chemotherapy is the use of medications to kill cancer
cells. It is a systemic therapy, meaning that the medication travels
throughout the body to destroy cancer cells. After colon cancer
surgery, some patients may harbor microscopic metastasis (small
foci of cancer cells that cannot be detected). Chemotherapy is
given shortly after surgery to destroy these microscopic cells.
Chemotherapy given in this manner is called adjuvant chemotherapy.
Recent studies have shown increased survival and delay of tumor
recurrence in some patients treated with adjuvant chemotherapy
within five weeks of surgery. Most drug regimens have included
the use of 5-flourauracil (5-FU). On the other hand, chemotherapy
for shrinking or controlling the growth of metastatic tumors has
been disappointing. Improvement in the overall survival for patients
with widespread metastasis has not been convincingly demonstrated.
Chemotherapy is usually given in a doctor's office,
in the hospital as a outpatient, or at home. Chemotherapy is usually
given in cycles of treatment periods followed by recovery periods.
Side effects of chemotherapy vary from person to person, and also
depend on the agents given. Modern chemotherapy agents are usually
well tolerated, and side effects are manageable. In general,
anticancer medications destroy cells that are rapidly growing and dividing.
Therefore, red blood cells, platelets, and white blood cells are
frequently affected by chemotherapy. Common side effects include
anemia, loss of energy, easy bruising, and a low resistance to
infections. Cells in the hair roots and intestines also divide
rapidly. Therefore, chemotherapy can cause hair loss, mouth sores,
nausea, vomiting, and diarrhea.
Radiation therapy in colorectal cancer has been limited
to treating cancer of the rectum. There is a decreased local
recurrence of rectal cancer in patients receiving radiation either prior
to or after surgery. Without radiation, the risk of rectal cancer
recurrence is close to 50%. With radiation, the risk
is lowered to approximately 7%. Side effects of radiation
treatment include fatigue, temporary or permanent pelvic hair
loss, and skin irritation in the treated areas.
Other treatments have included the use of localized
infusion of chemotherapeutic agents into the liver, the most common
site of metastasis. This involves the insertion of a pump into
the blood supply of the liver which can deliver high doses of
medicine directly to the liver tumor. Response rates for these
treatments have been reported to be as high as eighty percent.
Side effects, however, can be serious. Additional experimental
agents considered for the treatment of colon cancer include the
use of cancer-seeking antibodies bound to cancer-fighting drugs.
Such combinations can specifically seek and destroy tumor tissues
in the body. Other treatments attempt to boost the immune system,
the bodies' own defense system, in an effort to more effectively
attack and control colon cancer. In patients who are poor surgical
risks, but who have large tumors which are causing obstruction
or bleeding, laser treatment can be used to destroy cancerous
tissue and relieve associated symptoms. Still other experimental
agents include the use of photodynamic therapy. In this treatment,
a light sensitive agent is taken up by the tumor which can then
be activated to cause tumor destruction.
Next: What is the follow-up care for colon cancer? »
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