Viagra may provide more than a wake-up to a man's sex life — it may help the body's immune system fight cancer, a new study involving mice suggests.
Scientists in Germany genetically engineered mice to develop melanoma, the deadliest form of skin cancer, and found that when these mice were given Viagra in their drinking water, they lived twice as long as untreated mice.
The drug works because it "wakes up" the immune system to fight cancer, said study researcher Viktor Umansky, an immunologist at the German Cancer Research Center, in Heidelberg.
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Viagra and cancer
Researchers from John Hopkins University had discovered in 2006 that Viagra (which is drug manufacturer Pfizer's brand name for sildenafil citrate) boosted the activity of T cells in mice with cancer. T cells are part of the immune system, and they fight tumors.
The new study showed how this may work. Most tumors release chemicals that inhibit T cells, but "sildenafil switches off these suppressor cells and wakes up the sleeping T cells," Umansky said.
Umansky used mice that were altered to develop malignant melanoma, mimicking the way the cancer develops in people.
From laboratories to people
Dr. Adam Lerner, a professor of medicine and pathology at the Boston University School of Medicine, who was not involved with the study, agreed that the study showed mice "have a stronger immune system under the effects of sildenafil."
Umansky said most current cancer treatments have the effect of tamping down the immune system, and Viagra might offset this effect. But years of further research would be needed before Viagra could become a cancer treatment, he said.
The study was published Oct. 11 in the journal Proceedings of the National Academy of Sciences.
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