Colon cancer occurs when the cells in the colon or rectum grow and multiply
uncontrollably, damaging surrounding tissue and interfering with the normal
function of the colon or rectum. Colon cancer is the third most common
cancer diagnosed in the United States. Most colon cancers (about 70 percent)
are found in the first six feet of the large intestine. The other 30 percent
occur in the last 10 inches of the large intestine (rectum). Collectively
they are referred to as colorectal cancers.
One in 19 Americans will be diagnosed with colon cancer in their lifetime,
for an overall risk of 5.4 percent. Although colon cancer affects men
and women equally, rectal cancer is more common in men. When colon and
rectal cancers are found early, there is nearly a 90 percent chance for
cure. About 80 percent of colon cancer cases are sporadic, meaning that
cause is nonspecific or undetermined. The other 20 percent of colon cancers
are hereditary. People who have a first-degree family member with colon
cancer are more likely to be affected themselves. About 5 percent of this
group has a predisposition to hereditary non-polyposis colorectal cancer
(Lynch syndrome), a rare disease that generally strikes people aged 30 to 50.
There often are no symptoms of colon cancer in its early stages. Most colon
cancers begin as a polyp, a small non-cancerous growth on the colon wall
that can grow larger and become cancerous. As polyps grow, they can bleed
or obstruct the intestine.
- Rectal bleeding
- Blood in the stool or toilet after a bowel movement
- Prolonged diarrhea
- A change in size or shape of your stool
- Abdominal pain or a cramping pain in your lower stomach
- A feeling of discomfort or urge to have a bowel movement when there is no need
Many colon symptoms are not cancer, but if you notice one or more of these
symptoms for more than two weeks, see your doctor.
There are many methods for diagnosing colon cancer. Some of these procedures
are also used as screening devices to detect colon cancers in the early
stages, when treatment is more successful.
Fecal Occult Blood Test (FOBT): A stool sample is examined for traces of
blood not visible to the naked eye. If you do see blood in your stool,
contact your doctor immediately.
Fecal Immunochemical Test (FIT): FIT is a take-home test that detects blood
proteins in stool. A small, long-handled brush is used to collect a stool
sample, which is placed on a test card and sent to a lab for examination.
Sigmoidoscopy: A tiny camera with flexible plastic tubing is inserted into
the rectum, providing a view of the rectum and lower colon. This procedure
can also be used to remove suspicious tissue for examination.
Colonoscopy: A colonoscope is a longer version of a sigmoidoscope, and
can examine the entire colon. Patients must be sedated for a colonoscopy.
Double Contrast Barium Enema (DCBE): Barium is a chemical that allows the
bowel lining to show up on X-ray. A barium solution is administered by
enema; then the patient undergoes a series of X-rays.
Digital Rectal Exam: The doctor inserts a gloved finger into the rectum
to feel for polyps or other irregularities.
Carcinoembryonic Antigen (CEA): A blood test that determines the presence
of CEA, a substance, or tumor marker, produced by some cancerous tumors.
This test can also be used to measure tumor growth or assess if cancer
has recurred after treatment.
Stage 0: The cancer is found only in the innermost lining of the colon
or rectum. Carcinoma in situ is another name for Stage 0 colorectal cancer.
Stage I: The tumor has grown into the inner wall of the colon or rectum.
The tumor has not grown through the wall.
Stage II: The tumor extends more deeply into or through the wall of the
colon or rectum. It may have invaded nearby tissue, but cancer cells have
not spread to the lymph nodes.
Stage IIA: Cancer has spread beyond the middle tissue layers of the colon
or rectum wall or has spread to nearby tissues around the colon or rectum
Stage IIB: Cancer has spread beyond the colon or rectum wall into nearby
organs and/or through the peritoneum
Stage III: The cancer has spread to nearby lymph nodes, but not to other
part of the body.
Stage IV: The cancer has spread to other parts of the body, such as the
liver or lungs.
Surgery is the most common treatment for colon and rectal cancers. Depending
on the stage and location of the tumor, different surgical methods are used.
Local excision: If tumors are small enough, they may be removed with minimally
invasive surgery. Tiny incisions are made in the abdomen. A miniature
camera and surgical instruments are inserted. The surgeon uses computer
imaging to locate and remove the tumor.
Polypectomy: Suspicious or cancerous polyps on the colon wall can easily
be removed. A colonoscope is a long tube with a camera in the end. The
colonoscope is inserted in the rectum and guided to the area requiring
treatment, and a tiny, scissor-like instrument removes the polyp.
Colectomy: Surgeons remove the cancerous portion of the colon, along with
a margin of healthy tissue on either side, and then join the colon back together.
This procedure is also called a hemicolectomy or segmental resection.
Resection & colostomy: If the colon cannot be rejoined after removing
the cancer, surgeons will perform a colostomy. A stoma (hole) is cut in
the abdominal wall and attached to a segment of colon. Bodily waste goes
through the stoma into a plastic bag outside the body. Colostomies may
be temporary, allowing the bowel to heal before resection. However, about
15 percent of colostomies are permanent.
Radiation therapy may be used to destroy any colon or rectal cancer cells
that remain after surgery. Radiation is used most often on locally advanced
rectal cancers prior to surgery along with chemotherapy, or those that
cannot be treated with surgery. It can also be used to relieve cancer symptoms.
Chemotherapy can be used to shrink rectal tumors before surgery, or to
lengthen survival time after surgery. Chemotherapy is generally not effective
for advanced or recurring colon cancers.
Researchers are developing new drugs that are designed to seek out and
destroy specific types of cancer cells without affecting healthy cells.
New treatments are always being tested in clinical trials and some patients
with cancer may want to consider participating in one of these research
studies. These studies are meant to help improve current cancer treatments
or obtain information on new treatments. Talk to your doctor about the
clinical trials that may be right for you.