Sex Hormones Play a Role in Bladder Cancer in Women

NEW YORK FEB 08, 2006 (Reuters Health) - Menopausal status as well as age at menopause may modify the risk of women developing bladder cancer, researchers suggest in the February 1st issue of the American Journal of Epidemiology.

The risk in men is greater than that in women. Hormonal factors may be involved, say the Boston-based investigators, because "gender differences in cigarette smoking patterns, occupational exposures and other differences in known risk factor distributions cannot explain the excess bladder cancer observed for males."

Dr. Monica McGrath and colleagues from Brigham and Women"s Hospital and Harvard Medical School used the Nurses" Health Study to examine hormonal and reproductive factors in relation to bladder cancer risk in women.

During 26 years of follow up, 336 women developed bladder cancer.  Relative to premenopausal women, the incidence rate ratio was 1.93 in postmenopausal women. 

The team also observed a statistically significant increase in bladder cancer risk with earlier menopause (age 45 years or less) compared with later menopause (age 50 years or more). However, this association was significantly modified by cigarette smoking status.

The investigators point out that the drop in estrogen levels with menopause has been associated with bladder dysfunction and recurrent urinary tract infections.

It may be "that women who experience early menopause are at an increased risk of bladder cancer because they have recurrent urinary tract infections and concurrent inflammation starting at an earlier age."

Because inflammation and cigarette smoking are likely to act synergistically to increase risk, this hypothesis would also explain the strong interaction with smoking, according to the team.  

Additional studies, Dr. McGrath and colleagues conclude, should further investigate the biological effects of sex hormones in the bladder and the role of hormones in the development of bladder cancer.

SOURCE:

• Am J Epidemiol 2006;163:236-244.