Daily Viagra Dose Reduces Colorectal Cancer Risk When Given to Mice

Viagra became a household name when it became the first pill to treat erectile dysfunction, but there’s another reason why it’s captured the attention of medical researchers. According to a study released Monday, the little blue pill that ushered in a pharmaceutical revolution has the potential to be a game-changer in cancer prevention. A small, daily dose of Viagra has been shown in mice to significantly reduce the development of colorectal cancer, which is the third leading cause of cancer death worldwide.

Scientists representing Augusta University and the University of South Carolina explain in Cancer Prevention Research that, in their experiment, preventative Viagra treatment cut the formation of polyps in half. Polyps are abnormal cell clumps on the lining of the intestines that can turn into cancer. Colon polyps can be harmless, but the larger they grow, the larger the risk for colorectal cancer becomes. They often cause no symptoms, but in some cases, they can cause rectal bleeding and a change in bowel habits.

In this study, the scientists genetically engineered mice to produce hundreds of polyps, many of which resulted in colorectal cancer. When Viagra was introduced to the mice once a day via their water, it reduced colon inflammation and polyp formation by 50 percent. Augusta University biology professor and co-author Darren Browning, Ph.D., explained in a statement released Monday that “giving a baby dose of Viagra can reduce the amount of tumors in these animals by half.”

Viagra helps men with erectile dysfunction by relaxing their smooth muscle cells, allowing the vessels of the penis to more easily fill with blood. In this study, Browning and his team found that it also increases the levels of a chemical called cyclic GMP (cGMP), which affects the intestinal lining. While the scientists haven’t pinpointed exactly what’s going on, it looks like the increased cyclic GMP suppresses excessive cell proliferation and increases normal cell differentiation. That’s important if you want to reduce the chance of polyps turning cancerous, because proliferating cells are more likely to undergo mutations that cause cancer.

These results are in line with previous studies that found Viagra inhibits PDE5, a naturally occurring enzyme in colon cells that breaks down cyclic GMP, allowing it to widely reduce cell proliferation.

Now that the researchers know Viagra has this effect on mice, they say the next step is a clinical trial for the drug on patients considered at high risk of colorectal cancer. Viagra is already used safely as a treatment for premature infants with pulmonary hypertension. Time will tell if the erectile dysfunction drug will prove to be another tool in treating medical maladies.

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