Osteosarcoma, Part 1 — Introduction, incidence, symptoms, treatment, and possible
side effects
What is osteosarcoma?
Osteosarcoma (also called osteogenic sarcoma) is a cancer that makes
bone. It typically arises in bones but, rarely, will be found in muscles.
It is the most common
type of sarcoma (cancers of bone and soft tissues) in adolescents. However,
it is occasionally diagnosed in older adults. Osteosarcoma is usually
seen in teenagers
around the age of their growth spurts. In light of this, studies have
been and are being performed to see what, it any, the onset of this tumor
has to growth hormone
or its products. However, there is no indication that osteosarcoma is
more common in children who are taller or grow more rapidly. In addition
to being more
common in growing children, osteosarcoma is also more frequently seen
in the more active areas of bone, i.e., the growth plates (physes). These
growth plates are
present at the ends of long bones (near the joints) and in the prominences
of the pelvis. Osteosarcoma rarely arises in the spine.
Incidence and prevalence
In African Americans, incidence is 5.2 cases per million population younger
than 20 years each year. In whites, incidence is 4.6 cases per million
population younger than 20 years per year. Incidence is slightly higher
in males than in females. In males, incidence is 5.2 cases per million
population per year. In females, incidence is 4.5 cases per million population
per year. Osteosarcoma is very rare in young children (approximately 0.5
cases per million <5 y per y). Incidence increases steadily with age;
a more dramatic increase in adolescence corresponds with the growth spurt.
In children aged 5-9 years, incidence is 2.6 cases for African Americans
and 2.1 cases for whites per million population per year. In children
aged 10-14 years, incidence is 8.3 cases for African Americans and 7 cases
for whites per million population per year. In adolescents aged 15-19
years, incidence is 8.9 cases for African Americans and 8.2 cases for
whites per million population per year.
Symptoms
Children with osteosarcoma usually present with pain, occasionally involving
the adjacent joint. As sports and other injuries are much more common
than
osteosarcoma, the latter is frequently diagnosed only after a period of
time. Indications that the pain is not due to an injury, and therefore
deserves more extensive
evaluation, is a mass in the area of the pain, pain out of proportion
(both in severity and duration) to the inciting event, no specific history
of a traumatic event, and
prolonged complaints of pain even when the extremity is not in use (when
the child is at rest or at night). Although adults may have continuing
pain and disability from
chronic repetitive trauma (such as in carpal tunnel syndrome), this type
of exposure and the response to it is different in children; any prolonged
complaints need to be
evaluated.
The diagnosis of osteosarcoma is typically event on regular x-rays and/or
magnetic resonance imaging (MRI). The definitive diagnosis is established
with a biopsy.
Osteosarcoma may metastasize (spread through the blood stream) to the
lungs or other bones. Therefore, after the biopsy, the lungs are looked
at with a computed
tomography scan (CAT or CT scan); the rest of the bones are looked at
with a bone scan.
Treatment
Decades ago, treatment for osteosarcoma consisted only of removing the
tumor. Survival was extremely poor due to the development of metastases,
or spread of the disease to other parts of the body. During the1970's,
the use of chemotherapy was started (see section on medications, below).
This has led to a dramatic improvement in the survival from this cancer.
Treatment of the bone initially involved with the cancer consists of
removing this in the operating room. If too much muscle and bone has to
be removed, an
amputation may need to be done. However, this doesn't happen often. Usually
the tumor can be removed and the bone replaced either with a large piece
of metal
designed to look like the removed bone (similar to the joint replacements
done in older adults with arthritis) or with a piece of stored, frozen
bone that is the same
size as the removed bone. Due to the time needed to heal from such extensive
surgery, the child's activities are typically restricted for a period
of time. The degree
and length of restriction depends on the type of reconstruction and is
determined for each individual child. However, with reconstructions that
require bones to heal,
children may be out of vigorous activities for several months.
International studies continue in order to find the best combination
of medications to give, with the fewest side effects. Different kinds
of medications, called chemotherapy, are used to treat osteosarcoma. Chemotherapy
typically lasts about a year, consisting of 12 ‘courses’ of
chemotherapy. A course is a few days of medication, followed by about
3 weeks of rest. First, the child gets about 10 weeks of chemotherapy.
Then the tumor is removed surgically. This allows the tumor to be closely
evaluated to find out how much of it died as a result of chemotherapy.
The more of the tumor that is dead, the greater the chance the child will
survive long-term. After healing from the surgery, the child is placed
back on chemotherapy until the rest of the courses of medicine are completed.
Most chemotherapy for osteosarcoma is given through an IV. “IV”
stands for ‘intravenous’ or in the vein. It means that fluids
and drugs are administered slowly into a blood vessel. This lets stronger
medicine get to the tumor faster.
Possible side effects of medication
If the bone with the cancer is so weak that it could break, limitations
on activity made be in place from the time of initial diagnosis through
completion of therapy. After surgery, the limitations on activity depend
on the type of treatment used. Irradiated bone is more likely to break,
so child treated in this manner may have permanent restrictions on their
activities. For those treated with surgery, the degree and length of limitation
depends on how the bone was put back together. If the bone was put back
together with other bone (either grafted from another site in the child’s
body or donor bone), it is not unusual for restrictions to be in place
for several months while the bone heals. During this time, the child should
be mobile, with crutches or a walker if necessary for tumors in the pelvis
or legs.
Other physical restrictions may be the result of the chemotherapy treatments,
rather than of the cancer itself. The possible side effects of this chemotherapy
depend on the medications used and how the child responds to them. These
medications also affect other processes, such as the production of blood
cells. Common side effects of this include fever, increased susceptibility
to infection, and increased risk of bleeding with trauma. Chemotherapy
may result in low blood counts (red blood cells, white blood cells and
platelets).
Red blood cells (hemoglobin) carry oxygen throughout the body and give
us energy. If chemotherapy causes these cells to be low, the person may
be very tired. Their physical activity may be restricted during this time.
Sometimes, they need a blood transfusion to give them more red blood cells.
White blood cells help fight infection in our bodies. If these cells
become too low, the person may be more likely to catch infections that
are hard for them to fight off. If this happens, the person may be restricted
from being in big crowds (malls, football games, grocery stores, etc.)
where they may more easily be exposed to germs. If they do get an infection,
sometimes they must go into the hospital for IV (intravenous) antibiotic
treatments to help get rid of the infection. Many infections are carried
on our hands, by germs that get there when we cough, sneeze or touch a
surface that has germs on it. We can help people who are getting chemotherapy
(and everyone else, too) by using good hand washing techniques.
Finally, platelets are the part of our blood that prevent us from bleeding
too much or developing bruises. When chemotherapy causes platelets to
decrease, the person may have more bleeding when they are cut, or develop
bruises easily.
Osteosarcoma Part 1 — Introduction, incidence, symptoms,
treatment, and possible side effects
For more information, please contact:
Kathy Davis, MSEd, PhD
kdavis2@kumc.edu
(913) 588-6305