The prostate specific antigen (PSA) blood test is widely acknowledged as an imperfect screening method for prostate cancer (PCa). While it is sensitive for abnormal conditions within the gland, it is not specific for cancer. Thus, millions of men worldwide are sent for unnecessary exploratory prostate biopsies every year. Despite the fact that screening has been the main source of early detection when the most treatment options are open, it has also caused false negative biopsies, over diagnosis of insignificant PCa, and over treatment. Thus, in 2012 the U.S. Preventive Services Task Force (USPSTF) recommended against broad PSA screening.
More recently, CMS (Centers for Medicare and Medicaid Services) has proposed a measure that would attach an economic penalty to PSA screening. This means fining doctors who perform PSA tests. Aside from being a harsh measure, it may be alarmingly premature. A new study reveals early but compelling evidence that the reduction in PSA screening starting in 2013 is already leading to an increase in diagnosing men with bulkier and more aggressive disease that was not picked up because they weren’t screened.
Olsson et al. (2016) presented a poster titled “Trends in Histology of Newly Diagnosed Prostate Cancer Subsequent to USPSTF PSA Screening Recommendation” at the 2016 Genitourinary Cancers Symposium.[i] They tracked positive biopsy data from large urology practices in order to analyze any change in patterns before and since the USPSTF recommendation. They established a pre-recommendation baseline from 3,429 positive biopsy records from the years 2010-11, and compared these with similar records from 2013-15, focusing only on patients with a cancer diagnosis. Each positive needle core was recorded in terms of Gleason score (aggression), and the number of positive cores per patient was also included (cancer bulk). The following table shows their findings:
|Year||Positive biopsies||Gleason score 8-10||Positive cores|
|2010-11 (3,429 men)||39%||14.8%||31.3%|
|2013 (2773 men)||41.4%||19.7%||31.6%|
|2014 (2577 men)||42.6%||26.1%||34.6%|
|2015 (1767 men)||46%||25.4%||32.7%|
There is clearly a general upward-progressing trend toward more adverse pathology (higher Gleason, larger tumor bulk) since the 2012 recommendation.
While no one doubts that the PSA era resulted in the over diagnosis and possible over treatment of untold numbers of men, the Olsson study underscores a concern shared by a large number of urologists that the 2012 recommendation will lead to the under diagnosis of men with fast-growing, aggressive PCa because they weren’t screened in time. Prostate cancer has virtually no symptoms in its early stages. By the time a man has trouble urinating, blood in his urine or semen, or pain in his pelvic area or lower spine – all potential symptoms of well-established PCa – a window for a local cure may have closed.
The Olsson study is a cautionary tale, but a single study of only three years’ duration is unlikely to reverse the USPSTF recommendation. The question of how long it will take, and how many lives will first be lost to a disease that is highly treatable if found early, is a troubling one.
PSA screening is relatively inexpensive compared to, say, mammograms for breast cancer. While it’s true that an abnormal PSA frequently led to a biopsy referral, this was because TRUS biopsy was the only next diagnostic step; sadly, TRUS biopsy itself is highly imperfect.
Until the advent of a highly reliable biomarker, today’s diagnostic pathway should include:
- Considering a course of antibiotics to rule out infection
- Repeat PSA in three months
- A 3T mpMRI before biopsy. This accomplishes establishment of a baseline for future imaging (if no tumor is present) and the basis for an MRI-guided targeted biopsy for confirmed diagnosis of a suspicious region.
If the Olsson study is predictive, it serves as the canary in the coal mine to warn of a dangerous trend toward late diagnosis. The answer is not to jettison PSA screening just yet; rather, the solution lies in implementing the next step of multiparametric magnetic resonance imaging to best evaluate the situation. In light of the Olsson study, the USPSTF might well consider reviewing and revising their 2012 recommendation, and adding imaging, before more harm to PCa patients occurs because they were not screened.
[i] Olsson CA, Anderson AE, Kapoor DA. Trends in histology of newly diagnosed prostate cancer subsequent to USPSTF PSA screening recommendation. J Clin Oncol 34, 2016 (suppl 2S; abstr 68)