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Tumors(1) have a unique vulnerability(2) that can be exploited(3) to make them more sensitive to heat and radiation(4), researchers(5) at Washington University School of Medicine in St. Louis report.

The Washington University radiation oncology(6) researchers found that tumors have a built-in(7) mechanism that protects them from heat (hyperthermia(8)) damage(9) and most likely decreases the benefit of hyperthermia and radiation as a combined therapy(10).

By interfering with(11) that protection, the researchers have shown that tumor cells(12) grown in culture(13) can be made more sensitive to hyperthermia-enhanced(14) radiation therapy(15). The findings are reported in the May 1, 2008 issue of Cancer(16) Research.

Radiation therapy is a mainstay(17) of cancer treatment but doesn't always completely control tumors. For several years, raising tumor temperature has been investigated(18) as a radiation therapy enhancer(19) with few adverse side effects(20).

"Past research has shown that hyperthermia is one of the most potent(21) ways to increase cell-killing(22) by radiation," says senior author(23) Tej K. Pandita, Ph.D., associate professor(24) of radiation oncology and of genetics(25) and a researcher with the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital.

"But now we've found that heat also enhances(26) the activity(27) of an enzyme(28) called telomerase(29) in cancer cells(30)," he says. "Telomerase helps protect the cells from stress-induced(31) damage and allows some of them to survive. We used compounds(32) that inhibit(33) telomerase and showed that cancer cells then become easier to destroy with hyperthermia and radiation used in combination."