BUFFALO, NYProstate cancer screening protocols and treatment
for localized prostate cancer are less standardized than for other
cancers such as breast cancer, and treatment choices remain difficult
for many men and their physicians, Jerome P. Richie, MD, said at the
Surgical Oncology Symposium, hosted by Roswell Park Cancer Institute.
Prostate-specific antigen (PSA), discovered by researchers at
Roswell Park, offers physicians a dilemma. We find cancers and then
argue about how to treat them, said Dr. Richie, professor and
chair, Division of Urological Surgery, Harvard Medical School and
Brigham and Womens Hospital, Boston.
Although prostate cancer is very common in older men, not all
patients will die of their disease, Dr. Richie noted. It has
been shown that more than 30% of men over the age of 50 have clinical
prostate cancer at autopsy. There is a clear discrepancy between
prevalence and significance, he said.
The lack of randomized clinical trials has hampered the ability to
determine the true impact of the PSA test, Dr. Richie said. Unlike
mammography for breast cancer and the Pap smear for cervical cancer,
there has been no definitive proof of improved survival by regular
screening for prostate cancer with the PSA test.
Although use of PSA improves early detection, the test has a
high false-positive rate, and we need ways to improve the test to
better determine the difference between aggressive prostate cancer
and benign disease, he noted.
Dr. Richie mentioned age-specific guidelines to determine when
increased PSA levels are indicative of cancer (see Table
). Use of such guidelines is controversial and may be combined with
results from serial PSA tests, since an increase in PSA of 0.75
ng/mL/year is predictive of prostate cancer, he added.
Other issues surrounding PSA testing include when men should start
being screened and when screening should stop. Its
probably not efficacious to screen men who have less than 10 years
life expectancy, Dr. Richie said.
Sensitivity of PSA testing can also be improved by use of tests to
measure the percentage of PSA bound to proteins in the blood and the
percentage that is unbound, or free, PSA. The lower the percent
of free PSA, the more likely an elevation is to be from prostate
cancer rather than benign prostatic hyperplasia. The free PSA test
can eliminate approximately 30% of unnecessary biopsies without
significantly reducing the detection of prostate cancer, Dr.
The future direction for prostate cancer researchers is to find new,
sensitive markers for PSA, such as human kallikrein (hk-2), and to
develop randomized treatment trials.
Some trials have begun, but it will be 10 years before we have
meaningful data. In the meantime, physicians and patients need to use
multiple factors to determine the best treatmentradical
surgery, nerve-sparing surgery, brachytherapy, radiation therapy,
etc. We will continue to improve the treatments and decrease the
morbidity, but we are still lacking critical information about this
disease, Dr. Richie said.