‘Flu-like virus turned into terrifying news I had bladder cancer’
BK virus is very common, with most who catch it picking it up in childhood like a common cold
When Tim Tavender developed a common virus, he had no idea it was the start of what would later become a cancer diagnosis.
The 51-year-old from Southampton became ill with BK virus, also known as polyomavirus, in 2015 following a kidney transplant. Six years later, he went to the doctors after noticing blood in his urine, and was handed a devastating diagnosis of bladder cancer – which doctors now say was likely linked to his BK infection.
His story comes as new research shows the virus, which most pick up in childhood and has similar symptoms to the common cold, can trigger DNA damage that can lead to bladder cancer later in life.
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Mr Tavender said the new research could be “life-changing”.
“It was a terrifying experience,” he continued. “BK virus made me feel sub-par, like constantly having the flu, and lowering my immunosuppressants to fight it left me walking a medical tightrope.
“Then, in 2021, I noticed blood in my urine. It wasn’t just a little bit; it was claret. That visit to the doctor probably saved my life.”
The study published in the journal Science Advances used human tissue that lines the urinary tract and exposed it to the BK virus.
Researchers then looked for changes in DNA and found that, in the fight against the BK virus, “friendly fire” from enzymes meant to damage the virus can cause collateral damage in the cells’ own DNA.
“We found that DNA damage happens not only in infected cells but also in surrounding ‘bystander cells’, witnessing infection in their neighbours. This is important because it might explain why most bladder cancers have no sign of the virus in them when they are diagnosed many years later,” Dr Simon Baker from the University of York said.
The virus usually lies dormant in the kidney, but for transplant patients who have taken immunosuppressants to prevent the immune system from targeting the new kidney, it can allow the virus to reactivate and damage the kidneys and bladder.

Mr Tavender had a 13-hour-long surgery to remove his bladder and hopes the new research will spare others from going through what he did.
There are around 10,000 new bladder cancer cases in the UK every year. Current advice to prevent bladder cancer includes quitting smoking, but this study provides a new opportunity to help prevent the cancer through the identification and control of the BK virus earlier.
Dr Baker said: “We can now see how BK virus may contribute to bladder cancer, in transplant recipients and the general population, and explain why tumours show no trace of the virus years later.
“It gives us motivation to seek prevention strategies for both bladder cancer and the kidney damage caused by BK virus. With support from Kidney Research UK and York Against Cancer, our lab is developing new ways to control BK virus.”
Dr David Crosby, chief research officer at Kidney Research UK, commented: “These findings move us closer to understanding why some people develop bladder cancer and show how tackling BK virus early could one day stop these cancers from developing at all.”
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