Friday, December 28, 2012

PSA Test Results Are Back: To Celebrate or Not?

Barely ten minutes ago a nurse phoned from my primary care doc and gave the results of the PSA test taken last Friday, and roughly 3 months after the conclusion of my prostate cancer radiation treatment. She reported the PSA as 2.0 - which is "within normal range". While wifey was ecstatic, and this was definitely a positive,  considering it had gone up to 6.1 in June (before the biopsy and radiation treatment in September, see e.g. I noted we still had to wait to see what Dr. Hsu of UCSF made of it. Would he be satisfied with this first post-treatment result? We'd have to fax the lab report to him then see.

In the meantime, I am not hitting the panic button though I had hoped the PSA would have been closer to 1.5. But in a way it makes sense. As I noted before one can't compare a first PSA taken 3 mos. after radiotherapy (even high dose) with that taken after radical prostatectomy because in the latter case the whole gland is effectively removed, while in radiation it is left in. Thus, one still has production of prostate specific antigen by the remaining intact cells of the prostate, and one knows this is fueled by testosterone. (I haven't had a test for testosterone level, but if I had I am sure it would show close to normal levels.)

The other thing one must bear in mind is that the effects of radiation are progressive. Most statistics show that by five years after radiation high dose treatment the effects are almost identical to those after radical surgery. In other words, my time line will disclose increasing effects- many of them negative - such as damage to the erectile tissue, blood vessels etc. as the effect of the radiation dose continues on the cells. Over this increasing time line, one ought to see a decrease in PSA, though as I also noted before there may be aberrations which occur - temporary blips upward- and then declines. A "treatment failure" is only reported when there is no further decline. When I hit the lowest PSA over a timeline, say two years, that will be defined as the "PSA nadir". If it pops back up, we call it a "PSA bounce". Ideally we don't see too many bounces!

The "cure rates" reported in most studies tend to depend on two factors: 1) the quality of the treatment, and 2) the average risk type of the patient. Note most studies are "retrospective" or ex-post facto, only concluded after the fact. This is consonant with both the nature of the disease and also the treatment, especially radiation. The problem is that accuracy is limited by variations in "risk types" for different institutions. (Oncologists do their best to match risk types from institution to institution but for a number of reasons the matching process is less than perfect, introducing uncertainty.)

In one of the most notable studies, completed by Dr. Patrick Walsh (who invented the modern form of radical prostate surgery) at Johns Hopkins, the 15-year cure rates as reported in the journal 'Urology' in 2007, were 85%, 63% and 40%. These were for low-risk, intermediate risk and high risk disease, respectively. (Let's also bear in mind that even the best surgeons in one study group left cancer behind in 10% of cases - as determined by the "positive surgical margin rate". This is the frequency, usually given as a percentage, of leaving cancer cells behind over a number of 'n' surgeries performed.

Meanwhile, in the most prominent reported study for (low dose) seed implant brachytherapy, in the International Journal of Radiation Oncology (2007), the cure rates were 86%, 80% and 68% for low, intermediate and high risk cancer.  (By all considerations my high dose rate brachy results ought to compare even more favorably!) In other words, the two methods compare very well at least from these two studies. (A futher interesting point is that a Johns Hopkins study has shown that relapses after surgery occur on average five years earlier than seed implants.)

In the end, it's a waiting game. Over more time, perhaps at least two years, the chief oncologist will be able to definitely say that the battle has been "won" or perhaps only drawn, or lost. Right now I am just elated to have a much lower PSA than I had 6 months ago, and will take that as a 'W'.

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