A new factor in bladder cancer risk
People who use glucocorticoid drugs for a prolonged period of time may be at increased risk of developing bladder cancer, according to a new study by DMS researchers.
Glucocorticoids help suppress the immune system and are often prescribed to treat inflammatory conditions, such as rheumatoid arthritis and irritable bowel disease. Earlier research has identified links between bladder cancer and treatment with glucocorticoids, along with other drugs, following an organ transplant, as well as between glucocorticoids and other types of cancer. In 2001, for example, epidemiologist Margaret Karagas, Ph.D., and several colleagues reported an increased risk of certain skin cancers among patients who took glucocorticoids.
Glucocorticoids may suppress the immune system, says Karagas.
Prompted: More recently, Karagas led a population-based case-control study that examined the use of glucocorticoids among two groups of subjects—786 people with bladder cancer and 1,083 controls without bladder cancer. Karagas says the research was prompted by previous findings which had hinted at a possible connection between an impaired immune system and a susceptibility to being diagnosed with bladder cancer.
The researchers found that taking glucocorticoids orally was related to an increased risk of bladder cancer. In the general population, the overall risk of developing bladder cancer is about 1 in 27 for men and 1 in 84 for women. Those who had taken the drugs had an estimated 85% increase in risk of developing bladder cancer, and, among those with bladder cancer, patients who had taken glucocorticoids were more likely to have aggressive tumors.
Karagas says that these findings, which were published in the British Journal of Cancer, could reflect the possibility that glucocorticoids suppress the immune system, thereby allowing the development of tumors that would otherwise be caught and destroyed by the immune system. It's plausible, she says, that the drugs "may weaken the body's immunosurveillance mechanism against bladder tumors."
Prolonged: The paper's first author, Karl Dietrich, conducted the study while he was a student in Dartmouth's M.P.H. program. Now a first-year medical student at DMS, he says that "the most important finding in this study is the association with long-term use of glucocorticoids. Patients are commonly put on prolonged therapies, and it is important to be aware of other significant risks that could be associated with this treatment."
Both Dietrich and Karagas caution that the findings need to be replicated in other studies before they influence clinical practice. But, Karagas adds, "if glucocorticoids are found to increase risk of bladder cancer, it might indicate the need for closer monitoring of individuals who regularly take oral, systemic glucocorticoids."
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