Re: Should you trust health advice from internet forums

[Guest guest]

No but at least including the data from men that have extensive biopsies begins to provide those numbers.  They are not perfect but the same thing happened when PSA first started.To: ProstateCancerSupport Sent: Friday, December 12, 2008 2:33:54 PMSubject: Re: Should you trust health advice from internet forums

Dr. Chodak,

Sorry, I wasn't thinking about things quite correctly. For prostate

cancer, a positive biopsy is definitive but as you know, a negative

biopsy is not definitive. So the only way to do the study to produce

the data you would like is to perform a radical prostatectomy on

volunteers, so that one can biopsy the entire prostate. Of course,

since that won't happen, one must do one's best to evaluate the

available data about PCA3.

Jan

> > > >

> > > > I think it is time to do a video on the status of PCA3 but I

> > would

> > > urge caution as there is very little information on how to use

> the

> > > test because no good studies have been done yet with adequate

> > follow-

> > > up

> >

>

[Guest guest]

Actually, that is exactly the design of the proscar prevention trial.  Everyone, regardless of PSA was subjected to a biopsy at the end of the study and that is how we learned that no PSA guarantees the absence of cancer.  It found cancers even when the PSA was 1.0!.  So it can be done and without it, we will not really know if the test is worthwhileTo:

ProstateCancerSupport Sent: Friday, December 12, 2008 2:01:13 PMSubject: Re: Should you trust health advice from internet forums

Dr. Chodak,

No, it doesn't help.

There is no way that what you suggest would ever happen. In tumor

marker diagnostic accuracy studies, sensitivity is determined from

people with cancer as determined by a gold standard diagnosis such as

a biopsy. However, investigators could not get an IRB approved to

assess specificity as you suggest. That is, healthy volunteers should

not be subjected to a biopsy as part of an experiment. This was not

done for PSA studies, nor is it done for other tumor markers. Not

having a biopsy for healthy volunteers is a known limitation of these

studies.

One is faced with taking the available data and making a decision

about PCA3, whether as a sole marker or used in combination with PSA.

So waiting for a study that will never happen is not useful.

Jan

> > >

> > > I think it is time to do a video on the status of PCA3 but I

> would

> > urge caution as there is very little information on how to use

the

> > test because no good studies have been done yet with adequate

> follow-

> > up

>

[Guest guest]

In my experience as a patient and PCa survivor, one of the most difficult decisions for a urologist to make is to determine if and when to order a prostate biopsy! The only question concerning the PSA at this time is to determine is what relative percentage of cancers are caught in time when the PSA results is used to help determine when a biopsy needs to be ordered. The free PSA is often used to help further refine the decision making process. Obviously, even the most definitive test, the prostate biopsy still can occasionally miss the cancer. Problem in during clinical trials of newly developed tests is the huge cost and discomfort of the biopsy, especially when a significant large number of volunteers willing to submit to biopsy as part of the evaluation is req;uired! In my case, before I became eligible for Medicare, my PSA had been running at 9 and sometimes peaking at 11 for some two years, which worried by county public health nurse sick!

Louis. . . .

Re: Should you trust health advice from internet forums

Dr. Chodak,No, it doesn't help. There is no way that what you suggest would ever happen. In tumor marker diagnostic accuracy studies, sensitivity is determined from people with cancer as determined by a gold standard diagnosis such as a biopsy. However, investigators could not get an IRB approved to assess specificity as you suggest. That is, healthy volunteers should not be subjected to a biopsy as part of an experiment. This was not done for PSA studies, nor is it done for other tumor markers. Not having a biopsy for healthy volunteers is a known limitation of these studies.One is faced with taking the available data and making a decision about PCA3, whether as a sole marker or used in combination with PSA. So waiting for a study that will never happen is not useful.Jan> > >> > > I think it is time to do a video on the status of PCA3 but I > would > > urge caution as there is very little information on how to use the > > test because no good studies have been done yet with adequate > follow-> > up>

[Guest guest]

Dr. Chodak,

You say: " Actually, that is exactly the design of the proscar

prevention trial. Everyone, regardless of PSA was subjected to a

biopsy at the end of the study "

When I look at NEJM (2003)349;215:224, I see that not everyone was

biopsied. During the trial, a biopsy was recommended only for men

with certain PSA values and DRE results. At the end of the trial, all

were offered a biopsy, but around 25% of participants declined to

have a biopsy in both the treated and placebo groups. Maybe you are

referring to a different study?

This was a drug trial, which is different than a diagnostic assay

trial. Yes, information about PSA came out of this trial but that

information was incidental; it was not the purpose of the trial.

Jan

> > > >

> > > > I think it is time to do a video on the status of PCA3 but I

> > would

> > > urge caution as there is very little information on how to use

> the

> > > test because no good studies have been done yet with adequate

> > follow-

> > > up

> >

>

[Guest guest]

Quoting Dr. Chodak's reply to Larry:

>> I think there are way too many biopsies being done on men such as

>> yourself, prematurely.

I responded:

> When would be the " mature " time to perform a biopsy? And how would

> the medic and patient know?

On the same date, Dr. Chodak replied to me in full as follows:

> I am trying to avoid too many details of individual cases unless I am

> involved. †Please understand that †comments can be misinterpreted.

> †I am not trying to solicit here but I do offer consultations if

> someone wants more counseling and help managing their situation.

> †That was not the major thrust for the website, though, as I am no

> longer seeing patients and not trying to recruit new ones as some

> websites are trying to do.

With all due respect, I regret that I must observe that that is evasive;

not responsive to my question.

Regards,

Steve J

" Judge, and be prepared to be judged. "

-- Ayn Rand

[Guest guest]

Steve,

The problem is ... there is no good answer to your question. No one

really knows cause the testing just isn't there from a reliability

standpoing as evidenced by the large number of false positive PSA

tests.

Larry

>

> Quoting Dr. Chodak's reply to Larry:

>

> >> I think there are way too many biopsies being done on men such

as

> >> yourself, prematurely.

>

> I responded:

>

> > When would be the " mature " time to perform a biopsy? And how

would

> > the medic and patient know?

>

> On the same date, Dr. Chodak replied to me in full as follows:

>

> > I am trying to avoid too many details of individual cases unless

I am

> > involved. †Please understand that †comments can be

misinterpreted.

> > †I am not trying to solicit here but I do offer consultations if

> > someone wants more counseling and help managing their situation.

> > †That was not the major thrust for the website, though, as I am

no

> > longer seeing patients and not trying to recruit new ones as some

> > websites are trying to do.

>

> With all due respect, I regret that I must observe that that is

evasive;

> not responsive to my question.

>

> Regards,

>

> Steve J

>

> " Judge, and be prepared to be judged. "

> -- Ayn Rand

>

[Guest guest]

Steve,

The problem is ... there is no good answer to your question. No one

really knows cause the testing just isn't there from a reliability

standpoing as evidenced by the large number of false positive PSA

tests.

Larry

>

> Quoting Dr. Chodak's reply to Larry:

>

> >> I think there are way too many biopsies being done on men such

as

> >> yourself, prematurely.

>

> I responded:

>

> > When would be the " mature " time to perform a biopsy? And how

would

> > the medic and patient know?

>

> On the same date, Dr. Chodak replied to me in full as follows:

>

> > I am trying to avoid too many details of individual cases unless

I am

> > involved. †Please understand that †comments can be

misinterpreted.

> > †I am not trying to solicit here but I do offer consultations if

> > someone wants more counseling and help managing their situation.

> > †That was not the major thrust for the website, though, as I am

no

> > longer seeing patients and not trying to recruit new ones as some

> > websites are trying to do.

>

> With all due respect, I regret that I must observe that that is

evasive;

> not responsive to my question.

>

> Regards,

>

> Steve J

>

> " Judge, and be prepared to be judged. "

> -- Ayn Rand

>