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In the News: Prostate cancer and its discontents

By | January 7, 2012

If you’d like to know what I think of all this… Well, I could be induced to write a post about it, by a critical mass of timely requests (not people asking two years after the original post went up). But for now I will simply recirculate some news bits that caught my eye.

“Updated findings from one of the largest studies of prostate cancer screening show that the commonly used P.S.A. blood test did not save lives.

“…Last fall, the United States Preventive Services Task Force concluded that healthy men should no longer be routinely screened for prostate cancer using the prostate-specific antigen, or P.S.A., blood test. That decision was based on findings from five well-controlled clinical trials, including a major American study… which studied P.S.A. testing in nearly 77,000 men ages 55 to 74.

“In 2009, the PLCO trial reported that although annual P.S.A. screening did detect more cancers, it didn’t save more lives when compared with a group of men who were given routine medical care and tested for prostate cancer only when a problem was suspected.

“But at the time, the investigators had only 7 to 10 years of data. Because prostate cancer can take several years to develop, the investigators continued to collect data after reporting the initial findings. In a new paper published today in The Journal of the National Cancer Institute, the scientists report that the additional follow-up time didn’t change the overall conclusion: that regular P.S.A. testing does not save lives and can lead to aggressive treatments that leave men impotent, incontinent or both.”

Please – before you get all hot under the collar – note that these issues are about screening tests, not tests performed on men who we are concerned might actually have a fast-moving prostate cancer.

“Screening tests are performed on persons without any clinical sign of disease. [Emphasis added.]

“…Screening can detect medical conditions at an early stage before symptoms present. [BUT]… Like any medical test, the tests used in screening are not perfect. The test result may incorrectly show positive for those without disease (false positive), or negative for people who have the condition (false negative).

“In particular when screening for a condition of low probability the absolute number of false positives may be high although the percentage of false positives is very low; if the incidence of a condition is one in 10,000 and the probability of a false positive is 0.1%, 9 out of 10 positive results will be false.”

That last part might be hard to read! Let’s go back a step.

It means that if your chance of prostate cancer is very low, any positive test result is very likely to be false. A false positive.

The problem is, we can’t guarantee to you that it’s a false positive – without more testing (Biopsy! Owww!), and sometimes after treatment (such as prostate removal, with its consequences).

In many cases, the treatment does treat a cancer. It really is a cancer, and surgery really does remove it. The problem is, it is not very likely to be a cancer that would have killed you. More men die WITH prostate cancer than die FROM prostate cancer.

So you may have to deal with the consequences of invasive testing and possibly treatment, which you never would have had ever in the first place, if you had not been (inappropropriately) screened, when you did not have any symptoms of cancer. “U.S. incidence data suggest overdiagnosis rates ranging from 29% to 44% of all prostate cancer cases detected by PSA screening.”

“Overdiagnosis” means misdiagnosis – misdiagnosis according to the best diagnostic tests we have available. It means that 29-44% of the time, when a PSA screening test seems to indicate a cancer, further testing and treatment does not save lives, usually because those cancers would not have caused death.

One man’s vignette:
“John Shoemaker visited six doctors in his quest to find the best treatment for his early stage prostate cancer – and only the last one offered what made the most sense to the California man: Keep a close watch on the tumor and treat only if it starts to grow.

“…Shoemaker is one of more than 100,000 men a year deemed candidates for it by a government panel. That’s because their prostate cancer carries such a low risk of morphing into the kind that could kill.

“The risk for them is so low, in fact, that specialists convened recently by the National Institutes of Health say it’s time to strip the name “cancer” off these small, lazy tumors.

“…Some 240,000 men a year in the U.S. are diagnosed with prostate cancer. Earlier this month, the NIH-appointed panel found that most have the low-risk kind, a legacy of using problematic PSA blood tests to screen healthy men for possible signs of this slow-growing cancer.”

See?

More bad news:
“Older men considering robotic surgery for prostate cancer shouldn’t trust the rosy ads promoting the expensive technology over low-tech surgery. That’s according to a new survey that found complaints about sexual problems and urinary leakage were equally common after the two procedures.”

Also, just as mentioned above, “One study found that more than 120,000 American men diagnosed with prostate cancer every year are ideal candidates for observation, or watchful waiting. Still, the majority of them end up having surgery, radiation or other treatment instead.”

Also:
“Doctors and anaesthesiologists at the Asian Heart Institute got the scare of their lives when the robot they were wielding to perform an advanced prostate cancer surgery went kaput… and stopped taking instructions from the surgeons manouevering it… The surgery had to be aborted and the patient revived from anaesthesia.”

And:
“A cloud has descended over research into a biomarker for prostate cancer – early prostate cancer antigen-2 (EPCA-2) – which was described as “amazing” and appeared to overcome some of the shortcomings of prostate-specific antigen [PSA]… A paper about the biomarker was published several years ago in Urology (2007;69:714-720), but was retracted in October 2011… ‘The article contains findings that may be unreliable,’ the study authors write in their retraction.”
< sad trombone noise >

And:
“Recently published in the journal, Cancer, significant findings link blood clots to hormone-targeted prostate cancer therapy… Hormone therapy has known links to bone loss, hot flashes, impotence, increased risk for diabetes, fatigue and memory loss. Now add potentially fatal blood clots… 15% developed one or more blood clots over a four-year treatment period, more than double the 7% of non-[hormone-treated] patients who developed clots.”

And:
Dendreon soared almost 40% in value, or $3.02 a share, in active trading on Thursday after announcing that fourth-quarter revenue from its Provenge prostate-cancer vaccine would exceed earlier forecasts… For full-year 2011, Dendreon said sales of Provenge would total approximately $228 million.

What is Provenge?
It’s “a therapeutic cancer vaccine for prostate cancer. It must be prepared specifically for each patient. In metastatic prostate cancer, it has extended survival by about four months. It costs $93,297.60 for a course of treatment” [three shots].

And in other news:
“Following a positive blood test for prostate cancer, men are often advised to undergo radiation treatment. However, prostate cancer cells sometimes become resistant to the effects of radiation. Yet a new study indicates that treating these cells with the antioxidant resveratrol may improve their sensitivity to radiation… Resveratrol is the antioxidant that has garnered red wine so much attention over the past few years.”

And:
“Soybeans, more specifically soy isoflavones, a natural, nontoxic component of soybeans, were found to be effective in the fight against prostate tumors, and now, even lung cancer tumors, according to Golda Hillman, PhD, professor of radiation oncology at Wayne State University’s School of Medicine and the Barbara Ann Karamanos Cancer Institute.”

And:
“If you develop prostate cancer, taking aspirin cuts your risk of dying from it by more than half, compared to people who don’t take it. How? Basically, aspirin throws the kitchen sink at the disease. It blocks COX-2 enzymes, which help many cancers grow. It also shrinks estrogen production or its effects, starving certain breast cancers. Plus, it seems to flip a biochemical switch that tells cancer cells to die, and to clean up genetic mutations before they turn cancerous.”

Oh, and by the way:
“The steroidogenic activity of primary human benign prostate stromal cells is significantly increased by exposure to a Hedgehog agonist or by transduction of primary human benign prostate stromal cells with lentiviruses that expresses active Gli2, a transcription factor that is triggered by Hh signaling… Hedgehog/Gli signaling may be a factor in acquired intratumoral steroidogenesis of a prostate tumor through its actions on stromal cells in the tumor microenvironment and an influence for the development of castration-resistant prostate cancer.
(Don’t ask.)

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