It is not fully understood why bladder cancer develops. However, certain factors make bladder cancer more likely like the fact that smoking triples your risk of bladder cancer. Passive smoking may also increase your risk; exposure to certain industrial chemicals(eg, those used in printing and textiles, gas and tar manufacturing, iron and aluminium-processing industries); a long-term infection with the tropical disease, schistosomiasis(bilharzia) or a long-term or repeated bladder infection.
Attribution: BUPA