Anal Cancer
General
Information
Treatment Overview
Stages of Anal Cancer
Treatment by Stage
HIV and Anal Cancer
Video References
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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Video
References
1. Video: Radiation
Therapy Tutorial - The National Library of Medicine
http://www.nlm.nih.gov/medlineplus/tutorials/radiationtherapyintroduction/htm/index.htm
2. Video: Chemotherapy
Tutorial - The National Library of Medicine http://www.nlm.nih.gov/medlineplus/tutorials/chemotherapyintroduction/htm/index.htm
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