Sildenafil may slow cancer spread, Israeli study finds

Researchers at the Weizmann Institute of Science in Israel have reported that sildenafil, the active ingredient in Viagra, may slow cancer metastasis by limiting cancer cells' access to cholesterol. The study, published in the journal Cancer Research, was led by Dr. Yarden Ariaf in the laboratory of Prof. Ayelet Erez. Sildenafil works by inhibiting the enzyme phosphodiesterase-5, raising levels of the signaling molecule cGMP. That change affects cholesterol-transporting proteins and restricts cancer cells' ability to use cholesterol, a key component of cell membranes that is critical for cells breaking away from a tumor and forming metastases. The researchers noted that combining sildenafil with cholesterol-lowering statins could strengthen the effect, since sildenafil limits cells' use of existing cholesterol while statins reduce new cholesterol production. The study drew on cancer animal models, patient-derived cancer cell cultures, and health records covering roughly 5 million people over about 20 years. Analysis of the records showed that sildenafil use among cancer patients was associated with better survival rates, particularly when taken alongside statins. Erez said the findings point to a new biological link between intracellular signaling molecules and cholesterol regulation. The researchers said further studies are needed to determine sildenafil's effectiveness as a supportive cancer therapy.