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Anal
Cancer
General
Information
Treatment Overview
Stages of Anal Cancer
Treatment by Stage
HIV and Anal Cancer
General Information
Anal cancer, an uncommon cancer, is a disease in which cancer
(malignant) cells are found in the anus. The anus is the opening
at the end of the rectum (the end part of the large intestine)
through which body waste passes. Cancer in the outer part of the
anus is more likely to occur in men; cancer of the inner part
of the rectum (anal canal) is more likely to occur in women. If
the anus is often red, swollen, and sore, there is a greater chance
of getting anal cancer. Tumors found in the area of skin with
hair on it just outside the anus are skin tumors, not anal cancer.
A
doctor should be seen if one or more of the following symptoms
appear: bleeding from the rectum (even a small amount), pain or
pressure in the area around the anus, itching or discharge from
the anus, or a lump near the anus.
If
there are signs of cancer, a doctor will usually examine the outside
part of the anus and give a patient a rectal examination. In a
rectal examination, a doctor, wearing thin gloves, puts a greased
finger into the rectum and gently feels for lumps. The doctor
may also check any material on the glove to see if there is blood
in it. The doctor may give the patient general anesthesia, medicine
that puts patients to sleep, to continue the examination if pain
is felt during it. The doctor may cut out a small piece of tissue
and look at it under a microscope to see if there are any cancer
cells. This procedure is called a biopsy.
Anal
cancer is an uncommon malignancy, accounting for only a small
percentage (4%) of all cancers of the lower alimentary tract.
Clinical trials have evaluated the roles of chemotherapy, radiation
therapy, and surgery in the treatment of this disease.
Overall,
the risk of anal cancer is rising, with data suggesting that individuals
with human papillomavirus, and male homosexuals in particular,
are at increased risk of anal cancer.
The
prognosis (chance of recovery) and choice of treatment depend
on the stage of the cancer (whether it is just in the anus or
has spread to other places in the body) and the patient's general
health.
Anal
cancer is an often curable disease. The 3 major prognostic factors
are site, size, and differentiation (well-differentiated tumors
are more favorable than poorly differentiated tumors). Squamous
cell (epidermoid) carcinomas make up the majority of all primary
cancers of the anus. The important subset of cloacogenic (basaloid
transitional cell) tumors constitute the remainder. These two
histologic variants are associated with human papillomavirus infection.
Adenocarcinomas from anal glands or fistulae formation and melanomas
are rare. Treatment of anal melanoma is not included in this summary.
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Treatment
Overview
There are treatments for all patients with anal cancer. Three
kinds of treatment are used:
·
Surgery (taking out the cancer in an operation). Surgery is a
common way to diagnose and treat anal cancer. A doctor may take
out the cancer using one of the following methods:
Local
resection is an operation that takes out only the cancer. Often
the ring of muscle around the anus that opens and closes it (the
sphincter muscle) can be saved during surgery so that you will
be able to pass the body wastes as before.
Abdominoperineal
resection is an operation in which the doctor removes the anus
and the lower part of the rectum by cutting into the abdomen and
the perineum, which is the space between the anus and the scrotum
(in men)or the anus and the vulva (in women). A doctor will then
make an opening (stoma) on the outside of the body for waste to
pass out of the body. This opening is called a colostomy. Although
this operation was once commonly used for anal cancer, it is not
used as much today because radiation therapy with or without chemotherapy
is an equally effective treatment option but does not require
a colostomy. If a patient has a colostomy, a special bag will
need to be worn to collect body wastes. This bag, which sticks
to the skin around the stoma with a special glue, can be thrown
away after it is used. This bag does not show under clothing,
and most people take care of these bags themselves. Lymph nodes
may also be taken out at the same time or in a separate operation
(lymph node dissection).
·
Radiation therapy uses x-rays or other high-energy rays to kill
cancer cells and shrink tumors. Radiation may come from a machine
outside the body (external radiation therapy) or from putting
materials that produce radiation (radioisotopes) through thin
plastic tubes in the area where the cancer cells are found (internal
radiation therapy). Radiation can be used alone or in addition
to other treatments.
·
Chemotherapy uses drugs to kill cancer cells. Chemotherapy may
be taken by pill, or it may be put into the body by a needle in
a vein or muscle. Chemotherapy is called a systemic treatment
because the drugs enter the bloodstream, travel through the body,
and can kill cancer cells throughout the body. Some chemotherapy
drugs can also make cancer cells more sensitive to radiation therapy.
Radiation therapy and chemotherapy can be used together to shrink
tumors and make an abdominoperineal resection unnecessary. When
only limited surgery is required, the sphincter muscle can often
be saved.
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Stages
of Anal Cancer
Once anal cancer is found (diagnosed), more tests will be done
to find out if cancer cells have spread to other parts of the
body. This testing is called staging. To plan treatment, a doctor
needs to know the stage of the disease.
A
staging system for anal canal cancer that has been described by
the American Joint Committee on Cancer (AJCC) and the International
Union Against Cancer. Tumors of the anal margin (below the anal
verge and involving the perianal hair-bearing skin) are classified
with skin tumors. The following stages are used for anal cancer.
Stage
0 or carcinoma-in-situ
Stage 0 anal cancer is very early cancer. The cancer is found
only in the top layer of anal tissue.
Stage
I
The cancer has spread beyond the top layer of anal tissue, is
smaller than 2 centimeters in diameter (less than 1 inch), but
has not spread to the muscle tissue of the sphincter.
Stage
II
Cancer has spread beyond the top layer of anal tissue and is larger
than 2 centimeters in diameter, but has not spread to nearby organs
or lymph nodes (small, bean-shaped structures found throughout
the body that produce and store infection-fighting cells).
Stage
IIIA
Cancer has spread to the lymph nodes around the rectum or to nearby
organs such as the vagina or bladder.
Stage
IIIB
Cancer has spread to the lymph nodes in the middle of the abdomen
or in the groin, or the cancer has spread to both nearby organs
and the lymph nodes around the rectum.
Stage
IV
Cancer has spread to distant lymph nodes within the abdomen or
to organs in other parts of the body.
Recurrent
Recurrent disease means that the cancer has come back (recurred)
after it has been treated. It may come back in the anus or in
another part of the body.
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Treatment
by Stage
Treatments for anal cancer depend on the type of disease, stage
of disease, and the patient's age and general health.
Standard
treatment may be considered, based on its effectiveness in patients
in past studies, or participation in a clinical trial. Not all
patients are cured with standard therapy, and some standard treatments
may have more side effects than are desired. For these reasons,
clinical trials are designed to find better ways to treat cancer
patients and are based on the most up-to-date information. Clinical
trials are ongoing in most parts of the country for most stages
of anal cancer. For more information about clinical trials, call
the Cancer Information Service at 1-800-4-CANCER (1-800-422-6237);
TTY at 1-800-332-8615.
Treatment
of Stage 0 Anal Cancer
Treatment will probably be local resection to remove all of the
cancer.
Treatment
of Stage I Anal Cancer
Treatment may be one of the following:
1.
Local resection to remove all of the cancer.
2. Radiation therapy with or without chemotherapy. Some patients
may also receive therapy that involves placing radioactive substances
in the tissues surrounding the cancer to destroy the cancer (interstitial
radiation therapy).
3. If cancer cells remain following therapy, surgery removing
the anus and lower part of the rectum may be performed. An opening
will be made for waste to pass of out the body (colostomy) into
a disposable bag attached near the colostomy (colostomy bag).
4. If cancer cells remain following therapy, additional chemotherapy
plus radiation therapy may be performed.
5. Radiation therapy followed by interstitial radiation therapy.
Treatment
of Stage II Anal Cancer
Treatment may be one of the following:
1.
Local resection to remove all of the cancer.
2. Radiation therapy plus chemotherapy. Some patients may also
receive therapy that involves placing radioactive substances in
the tissues surrounding the cancer to destroy the cancer (interstitial
radiation therapy).
3. If cancer cells remain following therapy, surgery removing
the anus and lower part of the rectum may be performed. An opening
will be made for waste to pass of out the body (colostomy) into
a disposable bag attached near the colostomy (colostomy bag).
4. If cancer cells remain following therapy, additional chemotherapy
plus radiation therapy may be performed.
Treatment
of Stage IIIA Anal Cancer
Treatment may be one of the following:
1.
Radiation therapy plus chemotherapy.
2. Surgery to remove the lining around the colon and stomach plus
removal of the lymph nodes followed by radiation therapy.
Treatment
of Stage IIIB Anal Cancer
Treatment will probably be radiation therapy plus chemotherapy
followed by surgery. Depending on how much cancer remains following
chemotherapy and radiation, surgery to remove the cancer or surgery
to remove the anus and the lower part of the rectum (abdominoperineal
resection) may be done. During surgery, the lymph nodes in the
groin may be removed (lymph node dissection).
Treatment
of Stage IV Anal Cancer
Treatment may be one of the following:
1.
Surgery to relieve symptoms caused by the cancer.
2. Radiation therapy to relieve symptoms caused by the cancer.
3. Chemotherapy and radiation therapy to relieve symptoms caused
by the cancer.
4. A clinical trial evaluating new treatments.
Treatment
Recurrent Anal Cancer
The choice of treatment will be based on what treatment the patient
received when the cancer was first treated. If the patient was
treated with surgery, radiation therapy may be given if the cancer
recurs. If the patient were treated with radiation, surgery may
be used if the cancer recurs. The patient may also receive additional
chemotherapy and radiation therapy.
Clinical
trials are exploring the use of radiation therapy with chemotherapy
and/or radiosensitizers to improve local control.
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HIV
and Anal Cancer
The tolerance of patients with human immunodeficiency virus (HIV)
and anal carcinoma to standard fluorouracil/mitomycin chemoradiation
is not well defined. Patients with pretreatment CD4 counts of
less than 200 may have increased acute and late toxic effects;
chemoradiation doses may require modification in this subset of
patients.
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