Studies have shown that cancer tumors with cells low in oxygen often survive and continue to grow despite the treatments thrown at them. Early results from clinical studies suggest that a method of identifying these hypoxic tumors developed by a scientist at the University of North Carolina can lead to a greater understanding of treatment resistance. The method may also help doctors more effectively predict the outcome of cancer therapies.

"For many years it's been known that cancerous tumors that have low amounts of oxygen are relatively resistant to the effects of radiation treatment," said Mahesh Varia, MD, professor of radiation oncology at UNC-CH. "More recently we have learned that some hypoxic tumors are resistant to chemotherapy, and that patients treated surgically who have hypoxic tumors also do less well than patients with normally oxygenated tumors."

But of the methods available for identifying tumor hypoxia, only one does so on the cellular level that's significantly the most advanced in its clinical work. Moreover, it is highly accurate and does not require probing the patient's tumor directly during a complicated procedure. This is the pimonidazole hypoxia marker invented by UNC scientist, James A. Raleigh, PhD, professor of radiation oncology.

"When we started at UNC in 1988, the idea was to measure the amount of hypoxia in human tumors because that would predict which patients were going to do poorly after radiation. So this was a predictive assay to begin with," he said. "We spent a number of years proving it out in the laboratory and with animals in a veterinary setting and found it was feasible and low-tech."

The FDA has since given the go-ahead for testing it in human tumors as a diagnostic tool. In the test, the chemical pimonidazole is injected into the patient. As it circulates throughout the body, it binds only to cells that have low oxygen concentrations. The tumor is then biopsied, usually the next day. Usin
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Contact: Leslie Lang
LLANG@MED.UNC.EDU
919-843-9687
University of North Carolina School of Medicine
21-Oct-2000