A common bladder infection known as cystitis may be more than just an uncomfortable nuisance.
New research suggests it could act as an early warning sign of hidden cancers in the urinary and reproductive systems, particularly in middle-aged and older adults.
The study, published in BMJ Public Health, found that the risk of developing urogenital cancers—including prostate, bladder, and gynecological cancers—was sharply higher in the months following a cystitis diagnosis.
The danger appeared greatest within three months of infection, though an increased risk remained for several years.
Researchers analyzed health data from more than 3.5 million people in Sweden, covering the years 1997 to 2018.
Among them, over 600,000 people were diagnosed with acute cystitis for the first time. Most of these cases were diagnosed in primary care, and nearly three-quarters occurred in women.
Over an average 15-year follow-up period, just over 7% of participants were diagnosed with a urogenital cancer.
Men made up the majority of these cases, with prostate cancer the most common, followed by bladder and endometrial (womb lining) cancers. In nearly 10% of all cancer cases, a bout of cystitis had occurred beforehand.
The link was especially strong for prostate and bladder cancers. Men who had recently experienced cystitis were seven times more likely to be diagnosed with prostate cancer within three months than those who had not.
Their risk of bladder cancer was also significantly higher. Women faced a more than threefold increased risk of bladder cancer and a four- to eightfold higher risk of gynecological cancers in the same timeframe.
While the risks lessened over time, they did not disappear. Even five years after infection, both men and women who had experienced cystitis faced a small but ongoing higher chance of developing urogenital cancers. Men appeared to be particularly vulnerable, with cystitis raising their bladder cancer risk more steeply than women’s as they aged.
The researchers caution that this was an observational study, meaning it cannot prove cystitis directly causes cancer. Other factors, such as smoking, obesity, or undiagnosed diabetes, were not included in the data but may also play a role. Still, the sheer scale of the study adds weight to the idea that infections can serve as important markers of hidden health problems.
The findings suggest that doctors should consider cystitis as a potential red flag, especially when no obvious cause is found. In some cases, the infection could be a signal of underlying or developing urogenital cancers, as these conditions may compromise the urinary tract and make infections more likely.
For patients and clinicians alike, the message is clear: while most cases of cystitis are harmless and treatable, paying closer attention to bladder infections in middle and later life may help uncover serious diseases sooner.
