For 40 years, Oregon State University scientists have fought cancer with an unusual warrior: rainbow trout, a strain from Mount Shasta, Calif., to be specific.
“They’ve definitely done their work in the war against cancer,” said Gail Orner, an assistant professor who often works with the Sinnhuber Aquatic Research Laboratory.
OSU has 30,000 fish at the facility, just east of town off Highway 34. The lab includes a hatchery, and trout raised there are given food laced with carcinogens, as well as beneficial agents.
“We want to see what causes cancer in humans and what can prevent it,” Orner said. “There’s really nowhere else in the world that has the kind of water quality and facilities to be able to do this type of research.”
“It gives us the ability to do large-scale studies,” said Abby Benninghoff, an OSU toxicologist.
Some people are surprised that fish are useful in cancer lab studies, since they’re so far removed from humans on the evolutionary chain.
Although humans are more closely related to mammals such as lab rats, humans and rainbow trout share a tremendous amount of biology. And in some instances — such as aspects of liver cancer — fish are closer to humans than rodents in the way they react. The processes that cause cancer also are very similar throughout organisms, even down to bacteria.
Trout even provide researchers benefits, since they have a far lower natural rate of cancer than rodents, and they are far cheaper to produce for studies.
“A tank of 100 fish costs the same to raise as one rat,” Orner said.
Because researchers are able to use so many trout at such little cost, they can run more varied experiments, such as giving beneficial agents before, during and after exposure to carcinogens.
The latest published research from the facility found that PFOA, a chemical used in everything from plasticized cardboard food containers to stain-resistant and waterproof clothing, increased the incidence of liver tumors in trout. It appears that the compound acts like an estrogen, which are known to promote certain cancers.
“We’re not really at this point saying it is a cause for concern in humans, but there certainly should be more study,” Orner said. “It’s widespread in the environment, and it’s even been detected in people. It’s being used less now than it has been, but it’s still very much around.”
Benninghoff will do follow-up studies with similar compounds.
The lab was set up in the 1960s to study an outbreak of liver cancer in hatchery trout. It turns out a compound from moldy peanuts in the fish feed, called aflatoxin, was causing cancer in the fish. In developing countries, where up to 10 percent of the population dies from liver cancer, aflatoxin is a worry because people can’t necessarily afford to throw away moldy nut- and grain-based foods.
The largest cancer study ever done in vertebrate animals is continuing at the lab, to study the amount of aflatoxin that can cause cancer.
Researchers are about to complete the second of four segments in the study, which will include 50,000 fish. The project should last another year.

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