How does coffee affect bladder cancer?

In 2015, an analysis of 40 studies that investigated a possible association between coffee consumption and bladder cancer risk concluded that coffee is associated with a slight increase in the risk of bladder cancer, as noted by Scientific Reports. Specifically, this association was observed in males and nonsmokers.

Coffee consumption is not necessarily unhealthy and may reduce the risk of liver cancer, Parkinson's disease and diabetes, according to Mayo Clinic. Smoking, exposure to certain chemicals and the consumption of nitrates, such as those found in cured and smoked meats, may also increase the risk of bladder cancer, as reported by WebMD.