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* CANCER FACTS *
* National Cancer Institute *
* National Institutes of Health *
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Taxanes in Cancer Treatment
The taxanes are a group of drugs that includes paclitaxel (Taxol) and
docetaxel (Taxotere), which are used in the treatment of cancer. Taxanes
have a unique way of preventing the growth of cancer cells: they affect cell
structures called microtubules, which play an important role in cell
functions. In normal cell growth, microtubules are formed when a cell starts
dividing. Once the cell stops dividing, the microtubules are broken down or
destroyed. Taxanes stop the microtubules from breaking down; cancer cells
become so clogged with microtubules that they cannot grow and divide.
Paclitaxel
In 1984, NCI began clinical trials (research studies with people) that looked
at paclitaxel's safety and how well it worked to treat certain cancers. In
1989, NCI-supported researchers at The Johns Hopkins Oncology Center reported
that tumors shrank or disappeared in 30 percent of patients who received
paclitaxel for the treatment of advanced ovarian cancer. Although the
responses to paclitaxel were not permanent (they lasted an average of 5
months, some up to 9 months), it was clear that advanced ovarian cancer
patients could benefit from this treatment. In December 1992, the U.S. Food
and Drug Administration (FDA) approved the use of paclitaxel for ovarian
cancer that was resistant to treatment (refractory). Paclitaxel was later
approved as initial treatment for ovarian cancer in combination with
cisplatin. Women with epithelial ovarian cancer are now generally treated
with surgery followed by a taxane and a platinum (another type of anticancer
drug).
The FDA has also approved paclitaxel for the treatment of breast cancer that
recurred within 6 months after adjuvant chemotherapy (chemotherapy that is
given after the primary treatment to enhance the effectiveness of the primary
treatment), or that spread (metastasized) to nearby lymph nodes or other parts
of the body. Paclitaxel is also used for other cancers, including
AIDS-related Kaposi's sarcoma and lung cancer.
Side Effects of Paclitaxel
Like most cancer drugs, paclitaxel has side effects that can be serious. It
is important for patients to talk with their doctor about possible side
effects. For example, paclitaxel can cause hypersensitivity (allergic)
reactions such as flushing of the face, skin rash, or shortness of breath.
Patients often receive medication to prevent hypersensitivity reactions before
they take paclitaxel. Paclitaxel can also cause temporary damage to the bone
marrow. The bone marrow is the soft, sponge-like tissue in the center of
large bones that produces blood cells, which fight infection, carry oxygen,
and help prevent bleeding by causing blood clots to form. Bone marrow damage
can cause a person to be more susceptible to infection, anemia (a condition in
which the number of red blood cells is below normal), and bruise or bleed
easily. Other side effects may include joint or muscle pain in the arms or
legs; diarrhea; nausea and vomiting; numbness, burning, or tingling in the
hands or feet; and loss of hair. Nevertheless, for many patients with cancer,
the benefits outweigh the risks associated with this drug.
Paclitaxel Supplies: Old Problems and New Approaches
Paclitaxel is a compound that was originally isolated from the bark of the
Pacific yew tree (Taxus brevifolia). Early research using paclitaxel was
limited due to difficulties in obtaining the drug. The amount of paclitaxel
in yew bark is small, and extracting it is a complicated and expensive
process. In addition, bark collection is restricted because the Pacific yew
is a limited resource located in forests that are home to the endangered
spotted owl.
As demand for paclitaxel grew, NCI, in collaboration with other Government
agencies and the pharmaceutical company Bristol-Myers Squibb, worked to
increase the availability and find other sources of paclitaxel besides the
bark of the Pacific yew tree. This work led to the production of a
semi-synthetic form of paclitaxel derived from the needles and twigs of the
Himalayan yew tree (Taxus bacatta), which is a renewable resource. The FDA
approved the semi-synthetic form of paclitaxel in the spring of 1995. This
form of paclitaxel has now replaced the drug derived from the bark of the
Pacific yew tree.
Docetaxel
Docetaxel, a compound that is similar to paclitaxel, is also used to treat
cancer. Docetaxel, like the semi-synthetic paclitaxel, comes from the needles
of the yew tree. The FDA has approved docetaxel to treat advanced breast,
lung, and ovarian cancer.
Side Effects of Docetaxel
The side effects of docetaxel are similar to those related to
paclitaxel. Additionally, docetaxel can cause fluid retention, which is the
accumulation of fluid in the body. This can result in shortness of breath,
swelling of hands or feet, or unexplained weight gain. Before receiving
docetaxel, patients are often given medication to prevent fluid retention.
Current Clinical Trials with Taxanes
Researchers continue to look for new and better ways to use taxanes to treat
cancer. They are studying paclitaxel in combination with other anticancer
drugs to treat many different types of cancer, including lymphoma and cancers
of the head and neck, breast, esophagus, stomach, bladder, prostate,
endometrium (uterus), and cervix. In addition, researchers are studying ways
to overcome some cancers' resistance to paclitaxel. Clinical trials are also
in progress to test the effectiveness of docetaxel, alone or in combination
with other anticancer drugs, for several types of cancer, including cancers of
the head and neck, prostate, breast, lung, and endometrium (uterus).
This fact sheet was reviewed on 1/26/01
# # #
National Cancer Institute Information Resources
You may want more information for yourself, your family, and your doctor. The
following National Cancer Institute (NCI) services are available to help you.
Telephone...
Cancer Information Service (CIS)
Provides accurate, up-to-date information on cancer to patients and their
families, health professionals, and the general public. Information
specialists translate the latest scientific information into understandable
language and respond in English, Spanish, or on TTY
equipment.
Toll-free: 1-800-4-CANCER (1-800-422-6237)
TTY: 1-800-332-8615
Internet...
These web sites may be useful:
http://www.nci.nih.gov - NCI's primary web site; contains information about
the Institute and its programs.
http://cancernet.nci.nih.gov - CancerNet; contains material for health
professionals, patients, and the public, including information from PDQ about
cancer treatment, screening, prevention, genetics, supportive care, and
clinical trials, and CANCERLIT, a bibliographic database.
http://cancertrials.nci.nih.gov - cancerTrials; NCI's comprehensive clinical
trials information center for patients, health professionals, and the public.
Includes information on understanding trials, deciding whether to participate
in trials, finding specific trials, plus research news and other resources.
E-mail...
CancerMail
Includes NCI information about cancer treatment, screening, prevention,
genetics, and supportive care. To obtain a contents list, send e-mail to
cancermail@icicc.nci.nih.gov with the word "help" in the body of the message.
Fax...
CancerFax
Includes NCI information about cancer treatment, screening, prevention,
genetics, and supportive care. To obtain a contents list, dial 301-402-5874
or 1-800-624-2511 from a touch-tone telephone or fax machine hand set and
follow the recorded instructions.
Date Last Modified: 01/2001
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