Cancer breakthrough: Israeli scientists find viagra may starve tumours before they spread 

For nearly three decades, Viagra has been synonymous with treating erectile dysfunction. Now, scientists believe its active ingredient may have an entirely different legacy — helping prevent cancer from spreading, the deadliest aspect of the disease.

In what researchers describe as a first-of-its-kind discovery, scientists at the Weizmann Institute of Science in Israel have uncovered a biological mechanism through which sildenafil, the active ingredient in Viagra, could interfere with metastasis, the process that allows cancer cells to migrate from a primary tumour to other organs.

Their findings, published in the journal Cancer Research, raise the possibility of repurposing one of the world's most widely used medicines as part of future cancer therapies.

Why metastasis matters 

Most cancer-related deaths are not caused by the original tumour but by metastasis. Once cancer cells break away and establish new tumours in vital organs such as the lungs, liver or brain, treatment becomes significantly more difficult.

That is why scientists have long searched for ways to stop cancer cells from travelling in the first place.

The Israeli team focused on cholesterol, an essential building block that cancer cells require to form new cell membranes as they spread through the body. Their research identified a previously unknown pathway that cancer cells use to access cholesterol — and found that sildenafil can disrupt it.

Starving cancer cells of a vital resource 

The researchers found that sildenafil limits cancer cells' ability to tap into cholesterol reserves inside cells, effectively depriving them of a critical resource needed for metastasis.

But the cancer cells didn't surrender easily.

When their existing cholesterol supply was blocked, they switched on internal cholesterol production as a backup strategy. To counter this, researchers paired sildenafil with statins — the widely prescribed cholesterol-lowering drugs used by millions of people worldwide.

The dual approach proved far more effective in laboratory studies, simultaneously restricting access to existing cholesterol while reducing the body's ability to make more. Together, the drugs significantly curbed the biological processes associated with cancer spread.

Real-world patient data offered another clue 

Beyond laboratory experiments, the scientists also examined health records from millions of patients.

They observed that cancer patients who had taken sildenafil before their diagnosis appeared to have better survival rates than comparable patients who had never used the drug. The benefit appeared even greater among patients taking both sildenafil and statins.

While the findings show an association rather than proof of cause and effect, they provide an encouraging signal that warrants further clinical investigation.

A shortcut to new cancer treatments? 

Repurposing existing medicines has become an increasingly attractive strategy in medical research because these drugs already have well-established safety profiles, potentially reducing both development costs and timelines.

Viagra, originally developed to treat heart-related chest pain before becoming the world's best-known erectile dysfunction medication, could become the latest example if future clinical trials confirm the findings.

However, researchers stress that the work remains in the research phase. The current evidence comes from laboratory studies and analysis of existing patient data. Controlled clinical trials will be needed to determine whether sildenafil can safely and effectively reduce metastasis in cancer patients, identify which cancers respond best, and establish the optimal treatment regimen.

What comes next 

If validated in human trials, the discovery could reshape how doctors approach metastatic cancer—not necessarily by replacing existing treatments, but by adding a widely available, inexpensive drug to the arsenal against one of cancer's greatest threats.

For now, scientists caution that patients should not self-medicate with Viagra in the hope of preventing or treating cancer. But the study offers fresh evidence that sometimes the next breakthrough in medicine may already be sitting on the pharmacy shelf—waiting to reveal an entirely new purpose.