Valium Alarm

Does it promote cancer?

To cope with anxiety and tension, millions of people reach for a Valium, a tranquilizer that has become the U.S.'s most widely prescribed drug. Now comes a report guaranteed to make users of the drug anything but tranquil. According to a Canadian physiologist, Valium may promote the growth and spread of cancer.

Dr. David Horrobin's disturbing suggestion, presented last week in Toronto at the annual meeting of the American Association for the Advancement of Science, is primarily based on his and others' studies with tissue cultures and laboratory rats. In one experiment, Horrobin injected breast tumors into 20 cancer-free rats; half were given a salt solution, and the rest received doses of Valium roughly comparable to high dosages given humans. After four weeks, the mammary tumors in the Valium-treated rats were three times the size of those in the control group.

Horrobin also points to a British study of women with breast cancer, some of whom had been using Valium or other drugs for anxiety or depression. At diagnosis their cancers were more advanced, and after treatment they tended to recur more quickly than in the unmedicated women. The investigator attributed the more rapid growth to anxiety, but Horrobin believes that the tranquilizer's physical effects might be to blame. This is particularly ominous, says Horrobin, because "after a diagnosis of cancer, tranquilizer use increases two or threefold." The researcher adds: "Since nobody has bothered to look at tranquilizer use in patients receiving cancer therapy, all the studies comparing treatments may be messed up."

Horrobin claims that his work and press interviews on the tranquilizer led to his being forced out of a research position at the University of Montreal in 1979. Hoffmann-La Roche, the maker of Valium, was quick to dispute his findings last week. Among rats that spontaneously developed cancer, says the company, there was no speed-up in tumor growth when they were given Valium. Moreover, notes Hoffmann-La Roche, human epidemiological studies have revealed no link between cancer and Valium use. That argument, says Horrobin, is irrelevant since such surveys have measured only the incidence of cancer, not the rate at which tumors grow. The final verdict on Valium is still not in.

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