WHAT'S NEW ?
A SHORT ESSAY ON PSA
Ralph Valle is man dedicated to helping men with prostate cancer. A long time survivor himself, he has a depth of knowledge unequalled by many. He was selected in 2008 by the Prostate Cancer Research Institute as a recipient of the first Harry Pinchot Award for his "excellence in prostate cancer education, research, advocacy, and community support." and was also honoured by the prostate cancer education and support group US TOO International with the Edward C. Kaps Hope award as "an outstanding leader in an US TOO support group who has shown unselfish, dedicated service to prostate cancer survivors and their families." He is always prepared to share this knowledge and in July 2003 posted a piece on the PPML Mailing List. I think it summarises the key Issues on PSA very well and succinctly. Despite the time that has passed, his comments and views are still valid.
Talk about the confused and confusing world of prostate cancer. Lately in the press we read the following:
1. "A blood test used to look for early signs of prostrate cancer misses 82 percent of tumours in men under 60, according to a report out yesterday. The shock study also claimed the widely-used PSA test failed to detect 65 per cent of cancers in older men." Said Doctor Rinaa Punglia, from Harvard Medical School in Massachusetts
2. "Prostate cancer is being overdiagnosed and overtreated because of the misconception that PSA is primarily a reflection of prostate cancer," said Dr. Thomas Stamey, a Stanford urology professor and lead author of the study, which appeared in The Journal of Urology. "Prostate cancer, like all other cancers, cannot be detected at an early stage by a blood test," said Stamey. "What we need is a new marker."
Is this confusing or what? One study proposes that they are missing detecting cancer up to 82% of the time while the other indicate that we are overdiagnosing and overtreating PCa. What's new, Pauline? Who is wrong and who is right? Hey, welcome to the confused and confusing world of prostate cancer. It would be a less confused world if we could all understand the following:
a. PSA IS NOT cancer specific. IS NOT cancer specific. IS NOT cancer specific. Anyone could have an elevated PSA and NOT HAVE cancer while another man can have a "normal" PSA and HAVE cancer.
b. In most men, PSA protein does not belong in blood in an abnormal quantity
c. An elevation in serum PSA represents an indication that something is wrong in prostateland. It could be common inflammation, inflammation induced by a bacterium, abnormal gland enlargement or prostate cancer among several possibilities.
d. One elevated PSA is meaningless if not verified by a retest and if not appropriately treated to identify cause. There are commonsense steps involved in this and several non-invasive tests before deciding to proceed with more invasive tests.
e. Serialized PSA provides data to calculate PSA doubling time. Exponential growth in characterized by exponential increases in PSA. PSA doubling time (PSADT) can be as fast a week and as slow as 50 years. Fast doubling times are associated with prostate cancer and disease progression.
Testing with PSA fails to detect cancers, overdetects insignificant cancers and the crowning jewel is the lack of proof of all present treatments to improve survival. That has been the recent past and present paradigm of prostate cancer. The lack of clinical trials to positively prove the worth of early detection and the effect of the various treatments in proving a survival benefit is like an anchor around the neck of the disease. It holds it hostage and prevents any preliminary favorable information to even blossom before it is battered down by the lack of undeniable proof.
Presently there is a gray area of uncertainty in diagnosing PCa. The degree of disease aggressivity can not be totally resolved by biopsy indicators because there is a huge proportion of under and over staging as proven by surgical series (comparing biopsy results with pathology results after surgery). As mentioned above, PSA is not cancer specific and staging by rectal examination leaves a lot to be desired. Imaging tests do not have the resolution to determine if the cancer is localized or not. Probably the best measurement available to determine disease aggressiveness is PSA doubling time and that is not necessarily a linear parameter.
The value of early detection has to be associated with some action that effectively changes the course of the disease. Finding cancer early and doing nothing will definitely not change the course of the disease. The potential to change the course of early disease stems from lifestyle changes, alternative treatments to full blown treatments.
In summary, with the amount of uncertainty created by our limited diagnostic tools, a decision to treat or not could not be simply answered by painting prostate cancer as an indolent disease. It is a sad reality that the proponents of treatments have not provided the proper studies to demonstrate benefit and the decision is therefore left for the ill-prepared patient to sort out. This is the confused world of PCa we will live in until the benefit/no benefit of early detection and treatment are fully clarified.
And that's enough for tonight. Have a great evening.
Godspeed,
RalphV