Can Viagra Save You from Colon Cancer Death? The Answer is….Maybe

"This brings up an interesting question that should be tested in a prospective study [a study that watches patients moving forward rather than looking back at records]," Heather Yeo, MD, a colorectal surgeon who specializes in colorectal cancer, tells SurvivorNet.

Among the the 12,465 men who had stage I, II or III colon cancer, 1,136 had taken sildenafil (Viagra) at some point after their diagnosis. Reviewing four years and three months of medical records, the researchers found that those who had taken Viagra after their cancer diagnosis were 18% more likely to still be alive. Those who took Viagra after having open (versus laparoscopic) surgery for colon cancer were 39% more likely than those who didn't to survive the four-year and 3-month study period.

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The study suggests that the anti-impotence drug could help prolong life for men with colon cancer. It raises the question of whether Viagra should be added to standard colon cancer treatment.

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How Viagra Might Help

People who have high levels of activity in a gene called PDE5A tend to have a higher risk of death if they get colon cancer. Viagra, which belongs to a class of drugs called PDE5 inhibitors, blocks the activity of this gene. So, researchers have theorized that the little blue pill might be an undiscovered anti-colon cancer agent. In fact, a couple of years ago, a study found that a small daily dose of Viagra prevented colon cancer in mice. Keep in mind, sometimes the results of mouse studies turn out to hold true in humans, and sometimes they don't.

In the current study, the researchers hypothesize that Viagra may help restore the immune system after surgery suppresses it. The drug might also improve sensitivity to chemotherapy, the researchers speculate.

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More Research Is Needed

But, retrospective studies do have some weaknesses. In this type of study, researchers comb records of events that have already happened and try to find an association between a particular behavior (e.g. taking Viagra) and a particular result (in this case, dying or not dying of colon cancer).

This type of study design can play into the inherent biases of the researchers. That is, if researchers are looking specifically for a relationship between Viagra use and colon cancer death, they may be more likely to see it and overlook other explanations.

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"These associations are often confounded with things that aren't studied," says Yeo. "Those that take Viagra may be healthier to begin with. Men usually aren't prescribed this medication if they have heart disease for example."

This doesn't mean that Viagra doesn't improve colon cancer survival rates. But, it will take a large, randomized controlled trial — considered the gold standard in evaluating the effectiveness of a medical treatment — to prove it.

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