ABSTRACT
Screening for prostate cancer (PCa) is highly controversial, as accumulated evidence indicates that widespread,
routine prostate-specific antigen (PSA)-based screening reduces PCa mortality but at the cost of significant over-
diagnosis and over-treatment. PSA-based risk-stratified screening could capture much of the benefit of screening
while greatly reducing over-diagnosis. This promising approach uses men’s baseline PSA values to inform their
risk of future aggressive and/or fatal PCa and determine their frequency of further screening. Under this
approach, men with high baseline age-specific total PSA levels receive more frequent screening and men with
lower levels receive less frequent screening. This efficient approach is currently supported by at least three US
advisory agencies, but not by several others, including most notably, the US Preventive Services Task Force.
This agency recommends additional “validation studies” with “longer-term follow-up” before considering PSA-
based risk-stratified screening. Additional data are also needed to optimize each of the components of PSA-
based risk-stratified screening, including the: (1) age at which baseline PSA values should be obtained, (2) length
of tailored re-screening intervals, (3) tailored age at screening cessation, (4) tailored strategies for Black men,
as these men are at higher risk of aggressive and fatal PCa, yet remarkably under-represented in the screening
literature, and (5) prostate-specific kallikreins used for screening, as kallikreins beyond total PSA have also been
found to predict PCa risk and mortality and thus might help to optimize PSA-based risk-stratified screening.
Therefore, to address each of these gaps, we propose to leverage data and serum specimens collected in the
large racially-diverse Kaiser Permanente Northern California integrated health system, along with its long-
running (over 5 decades), embedded Multiphasic Health Checkups cohort and nested case-cohort to: (1)
evaluate the utility of initiating baseline PSA screening before age 50, (2) determine the optimal re-screening
interval after a baseline PSA test, (3) identify populations of men at age 60 who might consider stopping
screening, (4) explore whether Black men should initiate screening earlier and be screened more frequently than
White men, and (5) evaluate whether adding other prostate-specific kallikreins to total PSA enhances prediction
of clinically-relevant PCa. Our overall goal is to provide evidence for “smarter” or more nuanced PSA screening
strategies to preserve or enhance the mortality benefits of PSA screening, while greatly minimizing its harms
and costs.