Men with a history of gonorrhoea have a two-fold increased risk of bladder cancer, according to a new study.

The study - led by researchers at the Harvard School of Public Health in the USA and published in the British Journal of Cancer is the first prospective study to confirm the link.

Bladder cancer is the fourth most commonly diagnosed cancer in UK men and gonorrhoea is the second most commonly diagnosed bacterial sexually transmitted infection (STI) in the UK. Around 10,150 people are diagnosed with bladder cancer in the UK each year, and more than 4,800 people die of the disease.

The paper comes from the Health Professionals Follow-Up Study - which has monitored the health of 51,529 men in the USA since 1986 through detailed questionnaires and medical records. The researchers identified 286 cases of bladder cancer for which complete information on gonorrhoea history was available.

Gonorrhoea is an infection that often recurs, causing local inflammation and symptoms such as incomplete emptying of the bladder.

“The inflammation itself or the associated symptoms could be contributing to the development of bladder cancer,” says Dr Dominique Michaud, Assistant Professor of Epidemiology at the Harvard School of Public Health and lead author on the paper. “The severity and frequency of these symptoms may dictate the extent of the increased risk."

The researchers also found that a history of gonorrhoea increases the risk of invasive bladder cancer to a greater degree than superficial cancer. Patients with invasive cancer have a poorer prognosis.

“This study strengthens the suspected link between infection with the gonorrhoea bacterium and bladder cancer in men. The next step is to confirm whether the increased risk could be caused directly by the gonorrhoea infection or its symptoms,” comments Professor John Toy, medical director of Cancer Research UK, which owns the British Journal of Cancer.

“Further research is also needed to exclude the possibility that gonorrhoea is acting as a marker for the real cancer-causing agent, such as a separate infection.”

Professor Toy also added that a number of the biological processes that cause body tissues to become inflamed are also involved in the development of cancer, and that “scientists around the world are looking at how the inflammation might be causally linked to cancer in certain cases.”

The highest incidence rates for bladder cancer are generally found in industrially developed countries, particularly in North America and Western Europe. In the UK bladder cancer is the fourth most common cancer in males, with 7,201 new cases diagnosed in 2003. This compares to 2,947 female cases, giving a male/female ratio of 5/2. Smoking cigarettes is the principal preventable risk factor for bladder cancer in both men and women.