Metastatic cancer is cancer that has spread from the part
of the body where it started (called its primary site) to
other parts of the body. When cells break away from a cancerous tumor, they can
travel to other areas of the body through either the bloodstream or lymphatic
channels. When the cells travel through lymphatic channels they can become
trapped in lymph nodes, often those closest to the cancer’s primary site. When
the cells travel through the bloodstream they can go to any part of the body.
Most of these cells die, but occasionally they don’t. They settle in a new
location, begin to grow, and form new tumors. The spread of a cancer to a new
part of the body is called metastasis.
Even when cancer has spread to a new location, it is still
named after the part of the body where it started. For example, if prostate
cancer spreads to the bones, it is still called prostate cancer, and if breast
cancer spreads to the lungs it is still breast cancer. A person with breast
cancer that has spread to the bones is said to have breast cancer with bone
metastases. When cancer comes back in a
patient who appeared to be free of cancer (in remission) after treatment, it is
called a recurrence. Cancer may recur as:
§ Local recurrence (in or near the same organ
it developed in)
§ Regional recurrence (in nearby lymph nodes or
in the area that lymph nodes had been removed from)
§ Distant recurrence (involving any other part
of the body not included in local or regional recurrence). Distant recurrence
is also called metastatic recurrence.
For example, the cancer might recur in distant parts of body, such as, in
bones, the liver, or the lungs. This happens because some cancer cells have
broken off from the original tumor, traveled elsewhere, and begun growing in
these new places.
Sometimes the metastatic tumors have already begun to grow
when the cancer is first diagnosed. In
some cases, this metastasis is discovered before the primary (original) tumor is
found. If a cancer has spread widely throughout the body before it is
discovered, it may be impossible to find out exactly where it started. This
condition is called cancer of unknown primary, and is discussed further in a
separate American Cancer Society document.
Cancer cells that break off from a primary tumor and enter
the bloodstream can reach nearly all tissues of the body. Bones are one of the
most common sites for these circulating cells to settle in and start growing.
Metastases can occur in bones anywhere in the body, but they are mostly found
in bones near the center of the body.
Bone metastases are not the same as cancers that start in
the bone, which are called primary bone cancers.
Bone metastasis and primary bone cancers are very different. Primary bone cancer
is much less common than bone metastasis. For information on primary bone
tumors, refer to the American Cancer Society documents on “Bone Cancer,” “Osteosarcoma,” “Multiple
Myeloma,” and “
Bone metastasis is one of the most frequent causes of pain
in people with cancer. It can also cause bones to break (fractures) and high
calcium levels in the blood (calcium is released from damaged bones) It also
causes other symptoms and complications that can lower your ability to maintain
your usual activities and lifestyle.
§ Many people with cancer (except for those with nonmelanoma skin cancer) develop bone metastasis at some
point in the course of their disease.
§ Breast, prostate, lung, kidney and thyroid cancers
are most likely to spread to bones. § The
spine is the part of the skeleton most commonly affected by bone metastasis.
The next most common parts are the pelvis, hip, upper leg bones (femurs), and
the skull.
The first symptom of bone metastasis is almost always
pain. If you have cancer and begin to experience pain in a bone, you should
report it to your doctor right away. Sometimes, if the cancer isn’t promptly
treated, the bone may break. Your doctor will want to xray
the painful area and get scans or other imaging tests. Other
diseases, such as bone infections, arthritis, or just being very active can
also make bones hurt.
When a cancer is first diagnosed, doctors will recommend a
series of other tests to find out how far it has spread. Depending on certain
features of the primary tumor (such as its size and exact type), your doctors
will estimate your risk of metastasis and may recommend tests to search for it.
If none are found, then the primary cancer will be treated and
you will see the doctor at regular
intervals for followup
care. One of the main purposes of followup care is to
find out if the cancer
is beginning to come back either at the original site or elsewhere at a metastatic site.
Your symptoms with bone metastases can be mild at first. You may notice your appetite decreasing and have trouble sleeping because you are uncomfortable. These symptoms can make it hard to perform your usual activities.
Bone pain: Bone pain
is usually the first symptom of metastasis to the bone. The pain often comes
and goes at first. It tends to be worse at night and may be relieved by
movement. Later on, it becomes constant and may be worse during activity. It is
important to tell your doctor about bone pain. The bone might be so weakened
that it will break. This can often be prevented if it is found early.
Fractures: Broken
bones (fractures) can occur and cause severe pain. They may keep you from moving
much at all. In some cases, a fracture is the first sign of bone metastasis.
The most common sites of fractures are the long bones of the arms and legs and
the bones of the spine. Sudden pain in
the middle of the back is sometimes a sign of a cancerous bone breaking and collapsing.
Spinal cord compression: Cancer
in the backbone can press on the spinal cord. The spinal cord contains nerves
that allow you to move and feel what happens to your body. This is why pressure
on the spinal cord is one of the most serious complications of bone metastasis.
Not only can the pressure on the spinal cord cause pain, it can damage your
spinal cord so that your legs become numb and even paralyzed. Sometimes the
first symptom you may have of this problem is trouble urinating because nerves
from the spinal cord control the bladder.
Hypercalcemia:
If the cancer has metastasized to many
bones, you may develop hypercalcemia (high blood
calcium levels caused by release of calcium from bones). This can cause nausea,
loss of appetite, thirst, and extreme tiredness. Hypercalcemia
can even cause you to lapse into a coma if left untreated.
For these reasons, it’s very important for you to tell
your doctors and nurses about any new bone symptoms or changes in old symptoms.
Early detection and early treatment of bone metastasis can help reduce your
chances of further problems later on.
Sometimes, bone metastases are found before they have a chance to cause any symptoms. In these cases, results of lab tests and imaging tests (such as bone xrays or bone scans) done when the doctor is learning the stage of your cancer (called staging), or in a routine checkup after treatment is finished, point to possible bone metastasis.
During staging or followup of a cancer,
your doctor may get xrays of your bones. These
may show evidence of the cancer’s
spread to one or more bones. Xrays will not show bone
metastases unless the cancer has destroyed about half of the bone’s substance.
Bone metastases can change the appearance of bone in 2 ways.
In one way, the metastases dissolve some of the minerals in
the bone, which makes the bone
less dense. These are called osteolytic
or lytic
metastases, and appear on xrays as a dark
hole
in the graywhite
bone image. Bones with osteolytic metastases tend to
break very easily.
Other cancers, especially prostate cancers and some breast
cancers, cause osteoblastic
or
blastic
metastases that make the bone appear denser (sclerosis). On xrays, these metastases
appear as spots that are whiter than the surrounding bone. Xrays can also find fractures (breaks) in bones that are weakened by metastases.
Radionuclide bone scan: This
procedure helps show if a cancer has metastasized to bones. You will be given an injection of radioactive
substance called technetium diphosphonate.
The injection itself is the only uncomfortable part of the entire scanning
procedure. The amount of radioactivity used is low compared with the much
higher doses used in radiation therapy, and this low level of radiation does
not cause any side effects.
The radioactive substance is attracted to diseased bone
cells throughout the entire skeleton. Areas
of diseased bone will be seen on the bone scan image as dense gray to black
areas, called “hot spots.” These areas may suggest metastatic cancer, although
arthritis, infection, or other bone diseases can also cause hot spots. The
pattern of these diseases is usually different from the pattern caused by
cancer. To tell the difference between these conditions, the cancer care team
may use other imaging tests or take bone biopsies. Bone scans can find
metastases much earlier than regular xrays.
Not only are they useful in spotting bone metastases;
they can also track how they respond to treatments.
Sometimes bone scans fail to find areas of cancer spread
to the bones. This happens most often if the metastases are osteolytic.
In some patients, the scan may show no radioactivity in certain areas of bone
that have already been destroyed by the cancer.
Computed tomography (CT): The
CT scan is an xray that produces detailed crosssectional images of your body. Instead of
taking one picture, like the usual xray, a CT scanner
takes many pictures as it rotates around you. A computer then combines these
pictures into an image of a slice of your body. The machine will take pictures
of multiple slices of the part of your body that is being studied. This test
can help tell if your cancer has spread into your bones. It is especially important
when the bone metastases are only osteolytic, since
these metastases sometimes don’t show up in bone scans. Often after the first
set of pictures is taken you will receive an intravenous injection of a “dye”
or radiocontrast
agent that helps better outline structures in your body. A second
set of pictures is then taken.
CT scans can also be used to precisely guide a biopsy needle
into a suspected metastasis. For
this procedure, called a CTguided needle biopsy, you stay on the CT scanning table,
while a
radiologist advances a biopsy
needle toward the suspicious area. CT scans are repeated until the doctors are
confident that the needle is within the mass. A fine needle biopsy sample (tiny
fragment of tissue) or a core needle biopsy sample (a thin cylinder of tissue
about ½ inch long and less than 1/8 inch in diameter) is removed and examined
under a microscope.
CT scans take longer than regular xrays
and you need to lie still for 15 to 30 minutes on a table
while they are being done. But
just like other computerized devices, they are getting faster and your stay might
be fairly short. Also, you might feel a bit confined by the equipment you have
to lie in while the pictures are being taken.
The contrast dye will be injected through an IV (intravenous) line. A few people are allergic to the dye and get hives, a flushed feeling, or rarely, more serious reactions like trouble breathing and low blood pressure. Be sure to tell the doctor if you have ever reacted to any contrast material used for xrays.
Magnetic resonance imaging (MRI):
MRI scans use radio waves and strong magnets instead of xrays.
The energy from the radio waves is absorbed and then
released in a pattern formed by the type of tissue and by certain diseases. A
computer translates the pattern of radio waves given off by the tissues into a
very detailed image of parts of the body. Not only does this produce cross sectional
slices of the body like a CT scanner, it can also produce images that are
parallel with the length of your body. A contrast material might be used just
as with CT scans, but is used less often.
MRI scans are particularly useful for looking at the spine and
spinal cord. If your doctor thinks
your cancer is pressing on your
spinal cord, this is the best test to detect this. MRI scans are a
little more uncomfortable than CT
scans. First, they take longer often up to an hour. Also, you
are placed inside a tunnellike structure, which is somewhat confining. The machine also makes a mild thumping noise that bothers some people. Some places will provide headphones with music to block this sound out. In general, most people tolerate the procedure well.
Positron
emission tomography: Positron emission tomography (PET) usually uses
glucose (a form of sugar) that contains a radioactive atom. Cancer cells in the
body absorb large amounts of the radioactive sugar. A special camera detects
the radioactivity. This test is useful to see if the cancer has spread to lymph
nodes. PET scans are also useful when your doctor thinks the cancer has spread,
but doesn’t know where. PET scans can be used instead of several different xrays because they scan your whole body.
Serum tumor markers: Some
types of cancer release certain substances, called tumor markers, into the
bloodstream. Patients with these types of cancer may have blood tests at
regular intervals to see if levels of these markers are rising. For example,
high prostatespecific antigen (PSA) levels in a man
who has already had surgery or radiation therapy for prostate cancer suggest
the cancer may have come back, or, especially if the levels are very high, may
have spread to the bones. A high blood calcium level is another sign that the
cancer may have spread to the bones.
Other blood tests: When cancer spreads to certain organs, it may damage their cells or change their process. This may produce certain substances that can be found by routine blood tests. For example, bone metastases often cause high levels of alkaline phosphatase.
If you have had cancer in the past, your doctor can usually
diagnose metastatic cancer based on
how the bone scan or other xrays look. If any of your blood tests also suggest
metastatic cancer,
then this makes the diagnosis
even more certain. Because of this, biopsies are usually not needed. But if the
diagnosis is not clear, your doctor will need a biopsy sample from the abnormal
area to find out if it is cancer.
There are 2 types of biopsies: fine needle and core needle:
Fine needle biopsy or aspiration:
Fine needle aspiration (FNA) uses a very thin needle and a syringe
to take a small amount of fluid and small tissue fragments from the tumor. The
doctor can aim the needle at a suspicious tumor or area that can be felt near
the surface of the body. This type of biopsy of the bone is done only if the
bone is weakened or if the cancer has spread into the soft tissue around the
bone.
There are times that the suspicious area cannot be felt or
seen because it is deep inside the
body. Or the suspected metastasis may
be seen on an xray but there is no lump that can be
felt
on the surface of the bone. In
these cases, the needle can be guided by watching it during a computed
tomography (CT) scan.
Core needle biopsy: One
approach your doctor might take is to do a standard bone marrow
biopsy. In this procedure the doctor
puts a needle through the back of your pelvic bone after it
has been numbed with local
anesthetic. A core of bone and marrow will be removed. Often, this
test will show cancer even though
cancer wasn’t seen on xrays of the pelvis. The
benefit of this
is that it is simpler than trying
to biopsy the known sites because they may be hard to get at or particularly
painful to biopsy. But if there is a real question about a particular area of
bone then it can be biopsied with a needle.
Usually, the radiologist who does this uses xrays or CT scans for guidance. The needles used
for a core biopsy remove a small
cylinder of tissue (about 1/16 inch in diameter and ½ inch long).
Sometimes, needle biopsies don’t provide an answer and a
surgical biopsy is needed. In this procedure, the surgeon cuts into the bone to
remove a small part of the tumor (incisional biopsy). This procedure is not done very often.
Treatment options for people with bone metastases depend
on where the primary cancer developed, which bones it has spread to, and
whether any bones are severely weakened or broken. Other factors will also be
considered, such as specific features of the cancer cells (in the case of
breast cancer, for instance, whether they contain estrogen receptors), your
general state of health, and which treatments you have already received.
Most doctors feel the most important treatment for bone
metastases is treatment directed against the cancer. This is usually done with systemic
therapies. Systemic therapies enter the bloodstream and can
therefore reach cancer cells that have spread throughout the body. This is different
from local therapies, which are directed at a single area. Systemic therapies
include chemotherapy or hormone therapies that are taken by mouth or injected.
Also, bisphosphonate therapy can help to make
diseased bones stronger and help prevent fractures. It is used to supplement the
chemotherapy or hormonal therapy for bone metastasis. If systemic therapy is successful,
then the symptoms of the bone metastases will go away and new symptoms are not likely
to develop soon.
It also may be important to treat the bone problems. Local
treatments such as radiation therapy can relieve the pain in a bone by
destroying the cancer. Sometimes a bone such as your femur (thigh bone) might
look as if it is close to breaking. Your doctor will recommend that you have surgery
to prevent this. In this procedure, a surgeon places a thin steel rod in the
bone. It is much easier to prevent a damaged femur from breaking than to repair
it after it has broken.
This section begins with a summary of the types of systemic treatments used for patients with metastatic cancers. For more detailed information about treating metastatic cancer that has spread from a specific type of primary cancer, please refer to our information on each cancer type. The information on metastatic cancer will be included in the sections on treatment of advanced cancer, stage IV cancer, or recurrent cancer. The second part of this section contains information that focuses specifically on treating bone metastases.
Chemotherapy: Chemotherapy
uses anticancer drugs that are usually injected into a vein or taken by mouth.
These drugs enter the bloodstream and can reach cancer that has spread. Chemotherapy is used as the main treatment
for some metastatic cancers such as lymphomas and germ cell tumors of the
ovaries, testicles, or placenta. In many cancers, chemotherapy can shrink
tumors. This generally makes you feel better and reduces any pain you might
have. Chemotherapy drugs kill cancer
cells but also damage some normal cells. Therefore, careful attention must be
given to avoiding or reducing side effects. These depend on the type of drugs, the
amount taken, and the length of treatment. Temporary side effects might include
nausea and vomiting, loss of appetite, loss of hair, and mouth sores. Because
chemotherapy can damage the bloodproducing cells of
your bone marrow, you may have low blood cell counts. Low blood cell counts can
result in:
§ an increased chance of
infection (caused by a shortage of white blood
cells) § increased bleeding or bruising after minor cuts or
injuries (caused by a shortage of blood platelets)
§ fatigue (caused by low red
blood cell counts)
Most side effects go away once treatment is stopped. There are remedies to prevent or control many of the temporary side effects of chemotherapy. For example, drugs can prevent or reduce nausea and vomiting (these are called antiemetic drugs). For more information on chemotherapy, please see “Understanding Chemotherapy: a Guide for Patients and Families.”
Hormone therapy: Estrogen,
a hormone produced by the ovaries, promotes growth of some breast cancers,
particularly those cancers where tests can detect estrogen receptors. Likewise,
androgens, such as testosterone (produced by the testicles) promote growth of
most prostate cancers. One of the main ways to treat breast and prostate cancer
is to block these hormones.
There are several types of hormoneblocking therapy:
One strategy is to remove the organs that produce hormones. Removing the ovaries or testicles is a hormone therapy option for patients with breast cancer or prostate cancer, respectively. Postmenopausal women can be given aromatase inhibitors, which block the small amount of estrogen they normally produce. More often, drugs can be given to keep hormones from being produced. This is a common approach to hormone therapy for prostate cancer. Other drugs can be given to prevent the hormones from affecting the cancer cells For example, drugs such as tamoxifen block estrogen’s effects on breast cancers and antiandrogens block the male hormone effects on prostate cancer. Side effects depend on the type of hormone treatments used, but may include hot flashes, blood clots, loss of sex drive, and increased risk of other cancers
Immunotherapy: Immunotherapy
is a systemic therapy that helps a patient’s immune system recognize and
destroy cancer cells more effectively. Several types of immunotherapy are used
to treat patients with metastatic cancer, including cytokines, monoclonal
antibodies, and tumor vaccines. Most of these are still experimental. These
treatments are discussed in detail in American Cancer Society documents on
immunotherapy and the specific types of cancer for which this approach is
useful. For more information on immunotherapy, please see “ Immunotherapy.”
Radiation therapy uses highenergy rays
or particles to destroy cancer cells or slow their rate of
growth. Radiation therapy can be
used to cure primary cancers that have not spread too far from their original
site. When a cancer has metastasized to bones, radiation is used to relieve
(palliate) symptoms.
External beam radiation: The
most common way to deliver radiation to a bone metastasis is to carefully focus
a beam of radiation from a machine outside the body. This is known as external beam
radiation. To reduce the risk of side effects, doctors carefully figure out the
exact dose and aim the beam as accurately as they can to hit the target.
External beam radiation therapy for bone metastasis can be
given as a large dose at one time, or
in smaller amounts over 5 or more treatments.
Most radiation oncologists (doctors who specialize
in radiation therapy) prefer to give
the radiation over several treatments. The advantage of the 1dose
treatment
is fewer trips for therapy. The advantage of more treatments is that it is more
effective, since the number of patients who need retreatment
is reduced from about 25% to
between 5% and 10%..
Each treatment lasts only a few minutes. External beam
radiation is an excellent option if you have 1 or 2 metastases that are causing
symptoms. But if there are many metastases scattered throughout the body,
treatment is more difficult. In rare cases, some patients can benefit from radiation
therapy to the entire upper or lower half of their bodies. A few weeks later,
the other half of the body can be treated.
Radiopharmaceuticals: Radiopharmaceuticals
are radioactive substances that are used to treat bone pain caused by
metastatic cancer. They are injected into a vein and settle in bone areas that
contain cancer. Strontium 89 (Metastron) is the
radiopharmaceutical most commonly used for bone metastasis. It settles in bone
because it closely resembles calcium. Other radiopharmaceuticals have also been
studied. These contain radioactive atoms such as samarium 153, rhenium 186, and
rhenium 188. These radioactive atoms are bound to chemicals that attach to
bone.
The radiation given off by the radiopharmaceutical kills
the cancer cells and relieves the pain caused by bone metastases. If cancer has
spread to many bones, this approach is much better than
trying to aim external beam radiation at each affected bone. In some cases, the
radiopharmaceutical is used together with external beam radiation aimed at the
most painful bone metastases. Radiopharmaceuticals have helped many men with
prostate cancer, but it is less often used for other cancers.
Radiofrequency ablation: This technique uses a needle attached to electric current. The needle is placed into a particularly painful tumor that hasn’t improved with radiation therapy.. An electric current is delivered through the needle that destroys the tumor and relieves pain. This is usually done while the patient is under anesthesia.
Although surgery to remove a primary bone tumor (one that
started in the bone) is often done with the intent to cure, the purpose of
treating a bone metastasis surgically is to relieve symptoms. Bone metastases
can weaken bones, leading to breaks that tend to heal very poorly. An operation to stabilize the bone with a
metal rod or external device can prevent some fractures and, if the bone is
already broken, can rapidly relieve pain and help the patient return to usual activities.
If you can’t have surgery to reinforce a bone affected by
metastasis (because of poor general state of health, other complications of the
cancers, or side effects of other treatments) a cast may help stabilize leg
bones to reduce pain and avoid the need to stay in bed. Sometimes the cancer will spread to a bone in
the spine. This can grow enough to press against the spinal cord (spinal cord
compression). If not treated immediately, this can lead to paralysis. Surgery can relieve the pressure on the
spinal cord and prevent paralysis as well as helping to relieve the pain.
Radiation therapy is another option.
There are effective and safe ways to treat pain caused by
bone metastasis. In some cases, this may include treatments that kill the
cancer cells (chemotherapy or radiation therapy), slow their growth (hormonal
therapy), or reduce bone damage (bisphosphonates). If
the treatment does not relieve your pain, you should not hesitate to ask for
pain medicines. You may not want to ask
for or accept pain medicines, such as opioids,
because you think you will become addicted or that the medicines will make you
too sleepy to continue your usual activities. In reality, addiction rarely
occurs, drowsiness can be controlled, and being free of pain can help you
concentrate on the activities that are important to you. If you are in pain and have been given
prescription pain medicines, you should take them on a regular schedule. It is
better to prevent the pain than to treat it once it starts. For more
information on management of pain, please see “Pain
Control: A Guide for People with Cancer and their Families.”
Bisphosphonates are a group of
drugs routinely used to treat osteoporosis, a condition that weakens the bones.
Drugs in this category include alendronate, clodronate, editronate, ibandronate, zoledronate), and pamidronate. The most commonly used drug is zoledronate
(Zometa). Bisphosphonates
are also used to treat patients whose cancer has spread to their bones, as well
as patients with multiple myeloma, a cancer that
starts in the bone marrow. These drugs
help reduce bone pain, slow down bone damage caused by the cancer, reduce high blood
calcium levels (hypercalcemia), and lower the risk of
broken bones.
They are more effective when xrays show
the metastatic cancer is causing the bone to become
thinner and weaker (osteolytic metastases). They are less effective in treating
osteoblastic metastases (sclerosis).
Bisphosphonates may be taken by
mouth or given through a vein. Because the digestive system does not absorb
these drugs very well, and because they can cause irritation and ulcers in the esophagus,
bisphosphonate treatment for bone metastasis usually
is given intravenously every 3 to 4 weeks. Studies that compared pamidronate with zoledronate
found they both worked equally well. Zoledronate has a
slight advantage because it takes less time to inject. Clinical studies reported the most common
side effects to be fatigue, fever, nausea, vomiting, anemia (low red blood cell
counts), and bone or joint pain. But, the cancer or other drugs that the patients
were taking may have caused many of these effects. Bisphosphonates
may also cause arthritislike joint pain and muscle
pain. These can often be relieved or prevented with a mild pain reliever.
Bone Metastasis?
It is important to have open and honest communications
with your doctor about your condition. Your
doctor and the rest of your cancer care team want to answer all of your
questions. For instance, consider these questions:
§ What treatment options do I have for relieving bone
pain?
§ What treatment choices do I have for treating or
preventing broken bones?
§ Which treatments do you recommend, and why?
§ Is the treatment you recommend intended to cure the
cancer, to help me live longer, or to relieve or prevent specific symptoms of
the cancer?
§ What side effects are likely to result from the
treatment(s) that you recommend, and what can I do to help reduce these side
effects?
Research and Treatment?
As scientists learn more exactly how cancer cells break
off from a main tumor, spread through the blood and lymph circulation, and
begin to grow in a new location, they come closer to the goal of developing
treatments that can prevent bone metastases.
Angiogenesis research: Angiogenesis
(formation of blood vessels) research is one particularly exciting field that
may eventually lead to ways of preventing or treating metastatic cancer.
Several drugs that can prevent the formation of new blood vessels that cancers
need in order to grow and spread are now being tested in clinical trials. More antiangiogenesis drugs that appear even more effective are
almost ready for clinical trials.
Radiation therapy: Use
of radiopharmaceuticals is expanding, and researchers are studying new ways to
specifically target radioactive particles to cancer cells by combining them
with antibodies or certain chemicals. The technology for accurate delivery of
external beam and internal radiation therapy is constantly becoming more
sophisticated. Bisphosphonates:
The best ways to use these drugs to prevent bone metastases from occurring,
relieve bone pain, and prevent loss of bone strength are being studied. Most of the earlier studies of these drugs
focused only on breast cancer and multiple myeloma. Studies now being done are expected to soon
provide information on the value of these drugs in treating bone metastases
from other types of cancer. New bisphosphonates that
may be more effective are being developed and studied.
Targeted therapies: We
are learning how cancer cells are driven to grow by certain abnormal molecules
inside the cancer cell. Many drugs are being developed to target these abnormal
molecules and prevent their action on cancer cells. Several are close to being
available for treatment.
New Tests: A special
kind of PET scan for bone uses radioactive fluoride instead of glucose. The fluoride
is attracted to bone metastases better than the glucose. It is especially
useful with newer devices that combine a CT scan and a PET scan to even better
pinpoint the tumor. Search
for New Drugs: Although not as close to being developed, there is a
search for drugs that block the action of cancer cells on bone. Cancer cells
secrete chemicals that cause bones to dissolve. These chemicals are being
identified and it is hoped that drugs that block them will be developed.