Viagra does more than boost sex lives – it “wakes up” the body’s immune system to fight cancer, a recent animal study suggests.

In the study at the German Cancer Research Center, mice with melanoma were given Viagra (sildenafil citrate) in their drinking water. Those treated with the drug lived twice as long as mice who did not receive the Viagra.

Previously, in a 2006 U.S. study at Johns Hopkins University, researchers found that Viagra increased the activity of tumor-fighting T cells (a type of white blood cell).

That is, most tumors release chemicals that block T cell activity, but Viagra “switches off these suppressor cells and wakes up the sleeping T cells,” said study researcher Viktor Umansky, an immunologist in Heidelberg.

This finding marks the beginning of a new line of research. Years of additional research are necessary before Viagra could be used as a cancer treatment, Umansky adds. The study was published in the journal Proceedings of the National Academy of Sciences.