Viagra may slow cancer spread by trapping cholesterol in cells

A study in Cancer Research found that sildenafil, the active ingredient in Viagra, trapped cholesterol inside cancer cells and reduced lung metastases in mice, with men filling at least three prescriptions before diagnosis showing a 26 percent lower risk of death within five years. The drug blocks PDE5A, raising cGMP, which interferes with the NPC1 protein that normally moves cholesterol out of lysosomes, leaving cancer cells unable to use stored cholesterol for membrane building and movement. Adding statins, which block cholesterol production, strengthened the effect, with combined use linked to a 32 percent lower death risk. Analysis of 40,567 male cancer patients over 20 years adjusted for age, smoking, and other conditions, but lacked cancer stage and treatment data, so it cannot prove causation. Clinical trials are needed to confirm which cancers respond, and the medications are not yet cancer treatments.