Radiation Therapy for Colorectal
Cancer
About
Colorectal Cancer
Colorectal cancer includes
malignant or cancerous tumors of the colon and/or the rectum.
- The colon extends from the end of the small intestine to the
rectum. It consists of ascending, transverse and descending segments.
- The sigmoid colon is roughly S-shaped and is the lower portion
of the descending colon, leading into the rectum.
- The rectum is part of the digestive system. It makes up the
final five inches of the colon.
- Colorectal cancer can affect any of these areas.
Facts
About Colorectal Cancer
- This year, about 147,000 Americans will be diagnosed with colorectal
cancer.
- The disease affects men and women equally.
General
Risk Factors for Colorectal Cancer
The majority of colorectal
tumors are found in patients over age 50. However, the disease can
happen at any age so it is important to know your family history
and the following risk factors.
- Diet high in fat and red meat and low in fruits and vegetables.
- Personal history of colon cancer.
- History of polyps in the colon, ulcerative colitis or Crohn's
Disease.
Screening
for Colorectal Cancer
The American Cancer Society
recommends that, beginning at age 50, both men and women be screened
for colorectal cancer according to one of the following schedules:
- A yearly fecal occult blood test where your stool will be checked
for blood.
- A double-contrast barium enema every five years. During this
test, your colon is filled with a fluid containing barium. The
barium is then drained out and air is put into the intestine.
X-rays of the area are then taken to look for abnormalities.
- Every 10 years, a colonoscopy where the doctor uses a long,
lighted tube to look inside the rectum and the entire colon for
polyps or other abnormal areas that may be cancerous.
People who have any of
the colorectal cancer risk factors should consult with their doctor
about earlier, more frequent screening.
Signs
of Colorectal Cancer
Often there are no obvious
signs of colorectal cancer, but some symptoms can include:
- Change in bowel frequency, such as alternating episodes of diarrhea
and constipation.
- Bloody bowel movements or rectal bleeding.
- General abdominal discomfort.
- Unexplained weight loss.
- Chronic fatigue.
- Bloating.
- Unexplained anemia.
Diagnosing
Colorectal Cancer
Special tests to evaluate
the colon and rectum are used to detect and diagnose colorectal
cancer.
- A physical exam to assess your overall health, including a digital
rectal exam (DRE) to evaluate the rectum for abnormal masses.
- Fecal occult blood test.
- A sigmoidoscopy to look inside the rectum and sigmoid colon
for polyps or other abnormal areas that may be cancerous using
a thin, lighted tube.
- A double-contrast barium enema.
- A colonoscopy.
To determine for sure if
you have cancer, some tissue will be removed during sigmoidoscopy
or colonoscopy and examined under a microscope. This test is called
a biopsy. Your doctor may also request a CT or PET scan to see if
other body parts are affected.
Treating
Colorectal Cancer
The primary treatment for
cancers of the colon and rectum is surgery. For cancers that have
not spread, surgery alone may cure your cancer.
- Depending on the location and stage of your cancer, your doctor
may recommend chemotherapy and/or radiation therapy either before
or after surgery.
- For rectal cancer, radiation is usually given with chemotherapy.
It can be given before surgery (called preoperative or neoadjuvant
therapy) or after surgery (called postoperative or adjuvant therapy).
Depending on the location and stage of your tumor, preoperative
therapy may allow the surgeon to spare your anal sphincter. This
would avoid the need for a permanent colostomy and may reduce
the chance of the cancer coming back.
Understanding
Radiation Therapy
Radiation therapy, sometimes
called radiotherapy, is the careful use of radiation to safely and
effectively treat cancer.
- Cancer doctors called radiation oncologists use radiation therapy
to try to cure cancer, to control cancer growth or to relieve
symptoms, such as pain.
- Radiation therapy works within cancer cells by damaging their
ability to multiply. When these cells die, the body naturally
eliminates them.
- Healthy cells are also affected by radiation, but they are able
to repair themselves in a way cancer cells cannot.
After a diagnosis of colorectal
cancer has been established, it's important to talk about your treatment
options with a radiation oncologist.
External
Beam Radiation Therapy
External beam radiation therapy
involves a series of daily outpatient treatments to accurately deliver
radiation to the area at risk.
- Before beginning treatment, you will be scheduled for a simulation
to map out the area being treated. This will involve having X-rays
and/or a CT scan. You will also receive tiny tattoo marks on your
skin to help the therapists precisely position you for daily treatment.
- Treatment is given once a day, Monday through Friday, for about
six weeks.
- Newer technologies like 3-dimensional conformal radiotherapy
(3D-CRT) and intensity modulated radiation therapy (IMRT) are
being evaluated for use in treating colorectal cancer. Ask your
radiation oncologist for more information on these treatments.
Possible
Side Effects
People with colorectal cancer
often get chemotherapy while they are receiving radiation. Side
effects during treatment result from both the local effects of radiation
to the pelvic area and the systemic effects of chemotherapy throughout
the body.
- Possible side effects from radiation include more frequent bowel
movements, diarrhea, abdominal cramping, pressure or discomfort
in the rectal area, urinating more often, burning with urination,
skin irritation, nausea and fatigue. These are usually temporary
and resolve after your treatment ends.
- Chemotherapy side effects will depend on the specific drug you
receive.
- Side effects are not the same for all patients. Ask your doctor
what you can expect from your specific treatment.
- Many of these side effects can be well controlled with medications
and changes to your diet. Tell your doctor or nurse if you experience
any discomfort so it can be treated.
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