Re: prostate biopsy: Yes or not?

ralphv_in_az@xxxxxxxxx wrote:
George you are wrong on both counts! Since PCa death rates are much
higher at more advanced age, it is a fact that with extended life
expectancies in males, more deaths should be expected. The opposite is
happening here. The slower death rate is more related to early
detection AND better outcomes with localized treatments for earlier
disease.

The issue is whether or not declining mortality due to prostate cancer provides contrary evidence to the assertion that biopsy in itself increases the risk of metastatic prostate cancer.

George's argument, I agree, seems strange. It is almost as if he is arguing that a decline in overall mortality causes a decline in mortality due to specific diseases, e.g., prostate cancer, rather than vice versa. It is very hard to see how one could determine the truth of such an assertion. There could be indirect ways that might happen, but I don't see how you could separate out the factors specific to prostate cancer, such as early detection and better methods of treatment from such unspecified other effects.

But let's get back to the original question. Death rates due to prostate cancer definitely declined in the US after the introduction of PSA screening. I haven't been able to find comparable data for other countries, but Walsh does maintain that this didn't happen to the same degree in Sweden, where PSA screening has not been common. Suppose that is the case. Can we now say that the risk of a biopsy causing metastatic prostate cancer is negligible on the basis of this evidence. I think not because the PSA screening, by leading to earlier treatment of prostate cancer may reduce the risk of metastatic prostate cancer more than a biopsy increases it. Indeed many people believe that early screening and treatment do signficantly reduce the risk of metastatic prostate cancer, and a lot of preliminery evidence supports it. But it is still possible to doubt it without being intellectualy bankrupt. In any case, the best we can say is that the whole process, including PSA testing, biopsy where indicated, and early treatment, reduces the risk of metastatic prostate cancer. It could be that there is still some significant risk of biopsy resulting in metastatic prostate cancer but that this is more than counterbalanced by the other factors which reduce that risk.

On the other hand, if it is true that early detection and treatment have no signmificant effect on outcome, as George appears to believe, then your argument is inevitable. In that case, metastatic cancer rates should go up in screened populations compared to unscreened populations if it is true that biopsies signifcantly increase the risk of metastatic cancer. As best I can tell, no study has indicated such an increased risk of metastatic prostate cancer in a screened population.

It would be nice if someone came up with a clear definitive study which could isolate the different factors and tell use clearly what the risk of metastatic prostate cancer from biopsy really is, and how it depends on a variety of factors. But it is not clear to me how you could do such a study in the real world with real patients. Clearly few medical experts think this is a serious risk on the basis of what they know, and I at least am not going to try to second guess them.



Since you last checked, surgery has been shown to improve PCa's
disease-specific survival along with overall survival in a randomized
trial as compared to WW. I say that your comments as usual are far
off...and in spite of all these years have not changed much.

Source:
Bill-Axelson A, Holmberg L, Ruutu M, et al. Radical prostatectomy
versus watchful waiting in early prostate cancer. N Engl J Med.
2005;352:1977-1984.

The Homlberg, et. al. studies do appear to show in the Swedish context that radical prostatectomy reduces the risk of prostate cancer mortality and the risk of metastatic cancer when compared to WW followed by hormone therapy when needed. But since prostate cancer is not usually discovered through PSA screening in Sweden, this wouldn't seem to bear on the issue of whether biopsy by itself increases the risk. All the men in the Holmberg study persumably had biopsies.

P.S. I just did a Medline search the risks of prostate biopsy and found nothing within recent years suggesting an increased risk of metastatic prostate cancer from biopsy. I had previously found one or two reports of cancer cells being found along the biopsy track, but that is not the same as an increased risk of metstatic cancer because of reasons given previously. There was also a report of metastatic prostate cancer having been transmitted through a heart transplant, but transplant patients are subjected to strong immune suppressant drugs. So that raises the possiblity that people with severe immune definciency might develop metastatic prostate cancer because some cells escape in a biopsy and later become metastatic. Prostate cancer for such people is probably not at the top of their list of concerns.
.

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