DENVER — Prolonged oral glucocorticoid use may be associated with an increased risk of bladder cancer, findings from a population-based case-control study suggest.
The working hypothesis for the observed link is that the immunosuppression induced by prolonged use of oral glucocorticoids results in diminished immunosurveillance against growing tumors, Dr. Karl Dietrich explained at the annual meeting of the American Association for Cancer Research.
He reported on 786 patients with bladder cancer and 1,083 controls who underwent structured personal interviews regarding their history of medication use as well as the prevalence of standard risk factors for bladder cancer. Oral glucocorticoids had been used for 1 month or more by 61 cancer patients and 51 controls.
After adjusting for age, gender, and smoking, current prolonged users of oral glucocorticoids had a 2.2-fold greater risk of bladder cancer than individuals who had not taken the medication for at least 1 month, said Dr. Dietrich of Dartmouth University, Hanover, N.H.
The risk of bladder cancer was greatest in individuals who used oral glucocorticoids for a total of 5 years or more. They had an adjusted 3.4-fold increased risk of the malignancy, compared with nonusers.
Prednisone accounted for close to 90% of all oral glucocorticoid use in the study. Dose information was provide by 63 subjects. Those who took at least 50 mg/day had a 4.1-fold increased risk of bladder cancer; however, patients who took less than 49 mg/day didn't have a significantly greater rate of bladder cancer than nonusers.
Dr. Dietrich noted in an interview that the bladder cancer study is a sequel to earlier groundbreaking work led by Margaret R. Karagas, Ph.D., also of Dartmouth. Her similar population-based case-control study demonstrated that use of glucocorticoids for 1 month or longer was associated with an adjusted 2.3-fold increased risk of cutaneous squamous cell carcinoma and a 1.5-fold increased risk of basal cell carcinoma (Br. J. Cancer 2001;85:683-6).
Dr. Karagas was subsequently a coinvestigator in a confirmatory Danish population-based cohort study which concluded that patients with 15 or more filled prescriptions for oral glucocorticoids had a 2.5-fold increased risk of squamous cell carcinoma and a 1.5-fold increased risk of basal cell carcinoma (J. Natl. Cancer Inst. 2004;96:709-11).
The bladder cancer study results suggest that the same glucocorticoid-induced reduced immunosurveillance that allows growth and development of skin cancers also confers an increased risk of internal malignancies, Dr. Dietrich said.
The study was partly funded by the National Cancer Institute and National Institute of Environmental Health Sciences.