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Genetic Fingerprinting Shows Distinct Sarcoma Subsets

Genetic Fingerprinting Shows Distinct Sarcoma Subsets

ORLANDO—Genetic
"fingerprinting" of high-grade adult soft-tissue sarcomas by oligonucleotide
array ("gene chip") analysis revealed a number of distinct tumor subsets and
might help point to new therapeutic approaches, Robert G. Maki, MD, PhD, said
at the 38th Annual Meeting of the American Society of Clinical Oncology
(abstract 1611).

"For example, samples that show high expression of certain
human growth factor receptors may be targets for imatinib mesylate [Gleevec],"
he commented.

Dr. Maki, Dr. Neil Segal, and their colleagues from Memorial
Sloan-Kettering Cancer Center used gene chips to examine the activity patterns
of 12,500 genes in 51 samples of various adult soft-tissue sarcomas. Sarcomas,
which constitute less than 1% of all cancers, are very hetereogenous, he said.
Tissue diagnosis is critical. "You want to make sure you’re not dealing with
epithelial cancer or something else," Dr. Maki said, adding that treatment does
vary among different types of sarcoma.

"Genetic fingerprinting of adult sarcomas will be useful in
cases where pathologists disagree about a diagnosis or when the appearance of
tumor cells does not conclusively link them to a particular subtype," Dr. Maki
said.

His presentation focused extensively on malignant fibrous
histiocytoma (MFH), which has been something of a catchall diagnostic category
for ambiguous sarcomas. The genetic fingerprinting showed that certain MFH
sarcomas are, indeed, a distinct tumor subtype.

The researchers prepared complementary RNAs (cRNAs) from 51
high-grade adult soft-tissue sarcomas. These were hybridized to U95A Affymetrix
gene chips, and difference values were generated corresponding to levels of
expression of approximately 12,500 genes.

Cluster analysis was done using hierarchical clustering, and
data were visualized by multidimensional scaling.

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