Michaud DS et al. (2007) Gonorrhoea and male bladder cancer in a prospective study. Br J Cancer 96: 169–171

Whether infections and inflammation cause bladder carcinogenesis in developed countries is unclear, although two retrospective case–control studies suggested that men with a history of gonorrhea are at an increased risk of developing bladder cancer. Those findings could have been affected by recall or selection bias, since the risk assessment was done after bladder cancer was diagnosed. Michaud and colleagues, therefore, investigated this potential association in a subgroup of participants in the Health Professionals' Follow-Up Study—a longitudinal, prospective, US-wide cohort study on the relationships between nutritional factors and the incidence of serious illnesses in men.

Among 37,012 men (predominantly white, aged 40–75 years) who responded to a 1992 questionnaire that asked whether they had ever had a diagnosis of gonorrhea, Michaud and colleagues identified 286 men with incident bladder cancer. A history of gonorrhea was associated with an almost twofold elevated risk of bladder cancer (relative risk 1.92, adjusted for age, smoking history etc.). The association was stronger in invasive disease (relative risk 2.42) than in less-advanced disease, and there was no association with superficial disease, which makes detection bias an unlikely explanation for these results. The association between gonorrhea and bladder cancer was (nonsignificantly) strengthened by ever smoking.

The authors suggest that in individuals with a history of gonorrhea, inflammation that caused urinary symptoms, or increased urinary stasis from incomplete bladder emptying, could be involved in bladder carcinogenesis.