For the study, the researchers examined colon cancer tumors and non-tumorous tissue from 84 people in the United States, looking specifically at microRNA expression. To validate the U.S. findings, Hong Kong researchers also examined tumors and non-tumorous tissues from 113 Chinese adults.
The scientists found that 37 microRNAs were expressed in different levels in the tumor tissue. However, only one -- miR-21 -- was statistically significantly associated with poorer outcome. MiR-21 was also found in precancerous tissues.
Tumors that expressed high levels of miR-21 were associated with a 2.5 times increased risk of poor survival in the U.S. group, and 2.4 times increase in the risk of poor survival outcomes for the Hong Kong group.
"These are two different clinical cohorts [groups of patients] that found a single microRNA could have prognostic significance," said William Phelps, scientific program director in the research department of the American Cancer Society.
"The association was not only associated with a less favorable outcome, but was also associated with a poorer response to therapy, independent of the stage of the tumor. This seems to suggest that miR-21 is a very early marker that predicts a poorer prognosis," Phelps said.
However, both Harris and Phelps said this study's findings need to be duplicated in a larger group and in different populations before they could be applied in practice to help predict how a particular cancer might behave.
To learn more about colon cancer, visit the U.S. National Library of Medicine.
SOURCES: Curtis C. Harris, M.D., chief, human carcinogenesis
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