Monday, April 17, 2017

Examining The Basis For New Prostate Cancer Screening Recommendations

Image from a 3D staged biopsy - the only type that can eliminate false positives.

Many men are confused after the latest shift in advice from the U.S. Preventive Services Task Force's  2012 recommendations against prostate cancer screening.  At that time the advice was less screening, specifically via the PSA test, for men even past the age of 55, noting that the "possibility of the PSA lowering deaths from prostate cancer was very small." .  The reasons were not hard to grasp, mainly that one can get false positives which put the tested person on a track for even more invasive tests including unnecessary biopsies.  These can carry their own risks, including sepsis, impotence.

For example, the standard prostate biopsy consists of an extraction of from 10 to 20 cores of tissue.. Thus, a needle device is inserted into the rectum and each time extracts tissue from the gland after puncturing the rectal wall. The primary risk is for sepsis, which is why antibiotics like ciproflaxin must be administered in advance.

The procedure is usually done in the urologist's office without even a sedative and takes from 20 minutes to 45 minutes, depending on the number of sample cores taken. The chief side effects include: swelling and pain in prostate, possible problem urinating, and blood in urine, stools and semen. In the former two body fluids it can remain 1-2 days and in the last up to 3 months.

Even given all this, the biopsy is basically "random" and can miss up to 30 percent of cancerous lesions.  By contrast, the 3D staging biopsy entails up to 100 needle sampling insertions through the perineum to extract prostate tissue. The locations are again confirmed via trans rectal ultrasound for later mapping of all the samples to a 3D grid. The meticulous and exhaustive sampling ensures nothing is missed, hence represents the "gold standard" for prostate biopsies with up to 99 percent confidence of identifying all carcinomas.

The downside is, while vastly more accurate, it entails a far greater medical burden. Thus one must undergo a full surgery prep for general anesthesia, including being asked if you're an organ donor, and to leave an advanced medical directive .  The main risk is for hemorrhage, given the dozens of extractions.

A confirmation of lesion, however, then also is more accurately graded (by Gleason score) and can allow more choices in terms of treatment which one may not have with the standard biopsy. (For example if the standard biopsy reveals a higher Gleason score than the lesion actually merits, as I learned in my own case - after getting the 3D staging biopsy)

Now, in the new advice from the U.S. Preventive Services Task Force for men aged 55- 69, the conclusion is that the benefits of getting the test are marginally enhanced over the risks. This has been ascribed to "additional medical evidence from some clinical studies increasing the certainty about the PSA test reducing the risk of dying from prostate cancer.".   Even so, the panel's qualifying remarks noted the balance between pluses and minuses "was very close", and advised men aged 55-69 to consult their doctors in deciding whether to get the PSA.

Let's note that the statistics show that for every 1,000 men who get screened, an estimated 240 will test positive on the PSA. Some share of these - maybe 10 percent - will show false positives meaning those men will be faced with unnecessary biopsies. Those who decide to get treatment run the risk of developing impotence and incontinence as a result of surgery or radiation.

Owing to these facts,  the Task Force recommendation for those 70 and older stands by its 2012 position that "the benefits of screening do not outweigh the risks". .  The reasoning, again, is that because most prostate cancers are slowly growing, by the time one is diagnosed - say at 70 or 71 - he is still more likely to die from any other cause than cancer. (Up to 50 percent have a form of prostate cancer that doesn't spread or grow rapidly.)

In addition, an older guy getting screened sets him up for even more nasty complications, as well as costly treatments that may not be needed, and in fact are unwarranted. This is assuming such a test is positive with "high PSA" say 5.0 or 6.0.  One is then liable to be trapped in the "rabbit hole" of cancer quandaries summarized by the aspects below:

1) Cancer experts themselves can't agree on which primary treatment is best.
2) The same experts (oncologists) can't agree on which ("salvage") treatment for recurrent disease is best, or when to start it.
3) Most agree that if a guy has recurrent disease and a biopsy shows it has spread to the bones ("bone mets"), his days are basically numbered - though certain treatments (e.g. hormone) will allow some limited life extension.
Now also, once driven into the treatment domain one will have to decide how far to go, i.e. how many and what type of treatments are you willing to get in order to grab maybe ten years of life? Are you even willing to go the medical castration route?

Recall I earlier cited the Prolaris genetic test for the aggressiveness of a prostate cancer tumor,e.g.

I cited my own score of 6.6, corresponding with a 12.5 % specific risk of mortality at ten years. That translated to a 1 in 8  probability of croaking from it if I decided to do nothing.  As my oncologist (Dr. Crawford) pointed out, most guys at age 70 would make that bet.  I'm not doing it because he insists I have a better chance getting rid of the tumor completely using focal cryotherapy. But the point is for many "watchful waiting" might be an equally ok strategy.

Watchful waiting, especially if a guy is younger (say than 55)  - becomes a dicier proposition especially if the Gleason score is 6. By now most everyone has also seen or read of actor Ben Stiller's bout with prostate cancer, e.g.

But what they may have ignored is how the treatments and testing can often be worse than anything else - especially if one has a slow growing cancer. The risks of further treatments include sexual impotence and incontinence  The latter means wearing diapers - as in Depends - permanently. This is also why Otis Brawley of the American Cancer Society, has warned that most men need to be very careful before stepping through that testing and treatment door. Nine times out of ten the cancer will be so slowly growing that you can do 'watchful waiting' - especially for Gleason scores of 6 or less.

But ....also nine times out of ten a guy's significant other will insist the cancer come out as in out, out, out. The idea of living with a tumor that can grow - no matter how slowly - is a non-starter.  This is why it's a good idea for men and their spouses to have "the talk" ahead of time, say before the next PSA test. Decide in advance what PSA test value or threshold sets in motion further tests, including the "free PSA" test, MRIs and prostate biopsies (including MRI fusion biopsy.)

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