BCG exposure does not protect against PCa

April 1, 2005

Honolulu--Treatment with bacille Calmette-Gu?rin (BCG) for superficial bladder cancer is unlikely to confer any protection against prostate cancer in patients undergoing cystoprostatectomy, according to the results of a study presented at the annual Kimbrough Urological Seminar here.

Today, patients with superficial bladder cancer who are at high risk of tumor recurrence and progression often undergo intra-vesical therapy with BCG (Pacis, TherCys, TICE BCG), the gold standard of treatment for this tumor type. Failure with BCG and/or tumor progression typically results in cystoprostatectomy. About 25% of men who undergo cystoprostatectomy for bladder cancer also have incidental prostate cancer, according to previous studies.

The records of 197 patients (92%) were available for review; mean age of the patients was 65.8 years. Pathologic stage of bladder cancer at the time of cystoprostatectomy was as follows: T0, 6%; TIS, 9%; T1, 9%; T2, 29%; T3, 25%, and T4, 13%. Nine percent of patients had inadequate data for staging.

Fifty-five patients (27.6%) were found to have prostate cancer after cystoprostatectomy for bladder cancer. Incidence of prostate cancer in men who were not exposed to BCG was 28.4% compared with 26.0% in men exposed to BCG. Median Gleason sum was 6 in both groups. Z-test for proportions did not show a protective effect against prostate cancer in the latter cohort.

"The prevention and/or treatment of bladder cancer with BCG relies on the repeated exposure of the tissue to BCG. If the development of prostate cancer in humans is sensitive to BCG, the frequency or duration of exposure for this protective effect is unknown," Dr. Langenstroer said.

"With the retrospective limitations of the BCG data, it was not possible to determine if there was a threshold level of exposure that would confer a protective effect against prostate cancer. Thus, patients that didn't respond positively simply may have had an inadequate exposure to BCG."

Accurate BCG data Dr. Langenstroer added that another potential limitation of the study was the difficulty in obtaining accurate BCG data from patients referred to the tertiary care centers.

"It would be nice to be able to offer patients a treatment for bladder cancer that would reduce the likelihood of developing prostate cancer, but our study determined that BCG does not seem to confer such protection," Dr. Langenstroer said. "In the future, we might consider an international collaboration to compare men who were vaccinated with BCG with unvaccinated men from the same population to determine if the incidence of prostate cancer differs between the two.