The PSA Story: Early Detection Is Making a Difference
(This article is a portion of a paper on PSA screenings revised for QUEST)
If there were no effective treatment for prostate cancer, early detection would not be important, but studies are showing that patients treated with a radical prostatectomy have less deaths and less spreading of the cancer compared to those in a watchful waiting program.
If treatment of early cancer is effective, then the goal of early detection should be to detect potentially harmful cancers while they are still curable.
It does appear that early detection has had some effect on the statistics for successfully treating prostate cancer. A report from the National Cancer Institute (Hankey) stated, “...There is little uncertainty that PSA testing has left its mark on the vital statistics for prostate cancer. Several factors, especially the decline in the death from metastatic disease (the spreading of cancer) hold out the promise that PSA testing may lead to a sustained decline in prostate cancer mortality.”
If it were proven that early detection does improve outcomes, other issues still remain: Which patients benefit? How many cancers must be detected to save one life? What is the the risk-benefit ratio in relation to side effects? And what are the economic costs in relation to the benefits?
The controversies in prostate cancer screening come from trying to answer these questions.
One issue now at the forefront is when or at what age to begin screening for prostate cancer.
The American Cancer Society and the American Urological Association recommend that screening with PSA measurements and digital rectal exams be offered to men beginning at age 50 in the general population, at age 45 in high-risk men (African American or men with a positive family history), and at age 40 in men with strong family history of early-onset disease.
With our recent studies on the importance of PSA Velocity (rate at which the PSA rises over time), we recommend a baseline PSA at age 40.
Some people have suggested that early-age PSA testing results in “overdiagnosis”, referring to cancers that would not be diagnosed during the patient’s lifetime other than for the PSA results.
In actual clinical prostate cancer screening studies, most PSA detected prostate cancers have the features of clinically relevant tumors, meaning if they were left untreated, they would progress to life-threatening cancers.