|Researchers Find That Childhood Sarcoma Increases
Risk of Blood Clots
Researchers at the National Cancer Institute (NCI), part of the
National Institutes of Health, have determined that children and
young adults with a form of cancer called sarcoma are at increased
risk of having a thromboembolic event (TE) in their veins. Thromboembolic
events involve a blood clot in a vessel that can interfere with
normal blood flow. Clots can sometimes breaks loose and travels
through the blood stream to form new clots at locations in the
body where they can be life-threatening. TEs are almost always
treatable if detected early. Investigating the association between
sarcoma and TE is important because the majority of children with
sarcoma can be cured of their cancer, but the occurrence of TEs
could adversely compromise this success.
The study investigators also found that pediatric patients whose
cancer had spread beyond the original cancer site were more likely
to develop a TE than those with localized cancer. These findings
are from a study reported in the April 20, 2007 issue of the Journal
of Clinical Oncology. Researchers reviewed patient records
for 122 children and young adults treated for sarcoma in the Pediatric
Oncology Branch of the NCI between October 1980 and July 2002.
Cancer creates an environment that is conducive to thrombosis
because of the propensity of tumor cells to promote coagulation
as well the secretion of cytokines, or signaling compounds, that
trigger inflammation. In addition, factors common to cancer patients,
such as chemotherapy, surgery, immobilization, having a central
venous access device (such as a central line), and having other
diseases or conditions, all increase a person’s risk for blood
The study results showed that, over the 22-year study period,
16 percent of children and young adults with sarcoma developed
a TE. However, the researchers noted that this figure probably
underestimates the true frequency of TEs in this pediatric patient
population. Since this was a retrospective study of archival patient
records, most of the original physicians may not have specifically
looked for TEs, so some blood clots would have gone unrecorded.
Also, TEs often are asymptomatic and early screening was less accurate.
As the study observed, the rate at which TEs were detected in sarcoma
patients increased from 7 percent before 1993 to 23 percent since
1993 — an increase they attributed to improved screening
Children whose cancer had spread to other parts of the body were
2.5 times more likely to develop a TE than those whose disease
was localized. The most common locations of the blood clots were
in the deep veins of the legs and arms, the lungs (pulmonary embolism),
and the inferior vena cava, which is the large vein that carries
blood from the lower half of the body to the heart. Of the patients
who developed a TE, 40 percent had no symptoms related to their
blood clot. Thromboses were often detected around the same time
as the cancer diagnosis.
Previous research had shown a link between cancer and TEs in adults,
but data regarding TEs in adults may not be applicable to children
with cancer. Children differ from adults in the types of cancer
that occur, as well as in the number and types of co-morbid conditions.
The researchers only looked at sarcomas (cancers of the bone, cartilage,
fat, muscle, blood vessels, or other connective or supportive tissue)
in children, so not all pediatric cancer types were represented.
Sarcomas account for 15 to 20 percent of pediatric cancers and
include rhabdomyosarcoma, Ewing sarcoma, and osteosarcoma. Approximately
two-thirds of these cases can be cured.
A total of 23 TEs occurred in 19 of the 122 patients during the
22-year period of record keeping. Twenty-three percent of patients
with metastatic cancer developed a TE, compared to 10 percent of
patients with localized cancer, suggesting an association between
tumor burden and the risk of TE.
Senior researcher Alan S. Wayne, M.D., Clinical Director of NCI’s
Pediatric Oncology Branch at the Center for Cancer Research recommends, “Children
and young adults with sarcoma should be closely monitored for thrombosis
because these patients may not have any symptoms related to a TE
and because thromboembolism is a potentially life-threatening complication
that is almost always amenable to therapy.”
For more information on Dr. Wayne’s research, go to http://ccr.cancer.gov/staff/staff.asp?profileid=5603.
For more information on research in the Pediatric Oncology Branch,
go to http://home.ccr.cancer.gov/oncology/pediatric/.
For more information about cancer, please visit the NCI Web site
at http://www.cancer.gov, or
call NCI's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237).
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.