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On PSA Screening: Theme and Four
Variations (June 2006)
"AGE-Adjusted PSAV and Prostate Cancer Screening" - Abstract No. 1 at the
2006 Prostate Cancer Symposium:
Dr. Judd
Moul and colleagues presented data that adds useful sophistication to the
decision of whom to biopsy. They analyzed pre-biopsy PSA velocity in three
age groups and correlated PSAV with biopsy outcomes and identified PSAV
thresholds in each group above which there is greater likelihood of
detecting cancer than biopsies triggered by the traditional threshold of
concern, > 0.75 ng/mL/y. . The analysis was based on 11347 men (145593
tests) followed at Duke University between 1988 and 2005. The data was
limited to those men whose PSA was <4 ng/mL and PSAV <0.75 ng/mL/yr. In
the two younger groups the detection rate was 35% for men ages 40-49 whose
PSAV exceeded 0.25 ng/mL/yr (compared to 19% if cut-off of > 0.75 ng/mL/yr
was used); 57% for men in the age range 60-69 whose PSAV exceeded 0.50 ng/mL/yr
(compared to 25% for traditional threshold). In these two groups, the
sensitivity values were 0.519 and 0.398, respectively, compared to 0.265
and 0.306 for the traditional cut-off of 0.75 ng/mL/yr, while retaining
nearly the same specificity. The threshold of 0.75 ng/mL/yr was retained
for the >70 year old group. Dr. Moul's recommendations for thresholds:
>0.40 ng/mL/yr of age 40-49; >0.60 ng/mL/yr for age 60-69; and >0.75 for
more over age 70.
"Prostatitis
Confounds The Use of PSA Velocity for Prostate Cancer Detection" -
Abstract No. 4:
Catalona et
al. presented data from a small study that adds statistical support to the
awareness, current among clinicians, that a rapid rise of PSA during the
year preceding a proposed biopsy may be due to prostatitis. Their data was
based on an analysis of "ranges of PSAV and their association with
prostate cancer on first biopsy (quadrant or sextant biopsies) and the
probability of prostate cancer during the following two years" in a cohort
of 1797 men with normal DREs who were followed in a community based cancer
screening program. Results: when the PSAV (ng/mL/yr) was <0, 0-1.99,
2-3.99, and >4 cancer was found on the first biopsy in 30%, 28%, 22% and
13% respectively. Cancer was found within 24 months (using the same PSAV
groupings) in 39%, 36%, 28%, and 15%, and prostatitis histologically
present in 5%, 6%, 8%, and 13%, respectively. All p-values were <0.001.
"A Model of
the Natural History of Screen-Detected Prostate Cancer, and the Effect of
Radical Treatment on Overall Survival" - Abstract 5:
Clinicians
are well aware that PSA screening introduces "lead time" bias into the
diagnosis of prostate cancer, and are also aware that radical treatment of
screen-detected cancer may not yield an improvement over delayed
intervention or, in some instances, no primary therapy. This study
represents a valid effort to quantify these difficult to pin down issues
by comparing data from a variety of peer-reviewed, highly regarded
sources. While estimates can vary among investigators and analytic
methodologies may be challenged, the results presented in this abstract
are provocative and informative:
1) Based on
biennial PSA screening the lead-time estimates for men, aged 55-59 years,
diagnosed by PSA screening were 14.1, 9.3, and 5.0 years for men with
Gleason scores <7, 7, and >7.
2)
"Estimates of 15-year prostate cancer mortality for conservative
management of screen-detected prostate cancer ranged from 1% for Gleason
scores <7, 7-20% for Gleason score 7, and from 23-68% for Gleason scores
>7."
3) "For men
aged 55-59 at diagnosis, the predicted absolute 15-year survival benefit
from curative treatment of screen-detected prostate cancer was 0%, 11% and
23% for men with Gleason scores <7, 7, >7, respectively". Their
conclusion: "The case for curative treatment, rather than conservative
management, of screen-detected localized prostate cancer is strongest in
men with high grade disease".
Washington
State Legislation on Prostate Cancer Screening:
A bill
passed by the House and Senate and signed by Governor Gregoire, effective
June 7, 2006, is now a law "offering coverage for prostate cancer
screening ... to public employees and their covered dependents ...
provided that the screening is delivered upon the recommendation of the
patient's physician, advanced registered nurse practitioner, or physician
assistant". Interestingly the letters "PSA" do not appear in the bill, and
the initiative for "recommending" still rests with the health
professional, but this bill, lobbied for by the Washington State Prostate
Cancer Coalition, can easily be construed as a sign of increasing official
support for PSA screening.
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