Prostate Growth

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Bob Anthony - 03 May 2006 20:48 GMT

Does anyone know how fast the prostate can enlarge in a year? I know
this is something of an odd question, but perhaps there is an equation.
(Prostate growth in grams) and (Psa value) over a given time can yield
more psa due to enlargement rather than the supposed slow growth rate of
pca. Again, this would be just an approximation. I'm not aware of any
studies on the subject.
Hypothetically, if a 35 gram prostate doubled in size within a year, if
this is even possible, and the psa was 2.5 at the time of the 35 gram
point, how would this effect psa at the 70 gram point in there was no
pca present?
If pca was present at the 35gm /2.5 psa point, then is it feasible that
the larger rise in psa could be attributed more to the enlargement,
rather than the pca?

B.A.

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ron - 03 May 2006 21:36 GMT

Bob...Dr. Strum uses the following equation to predict the PSA expected
from a non-cancerous gland:

Benign PSA = 0.067 x gland volume (or weight)

So a 35 gm gland that is non-cancerous might be expected to produce a
PSA of 2.35 ng/ml; 4.70 from a 70 gm benign gland. Some other docs use
0.10 as the multiplication factor...Ron

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Bob Anthony - 03 May 2006 22:39 GMT

Thanks Ron

Then a 56 gm benign prostate would produce 3.75 and 5.6 of psa
respectively. After RLRP in 12/04 my prostate weighed in at 56 gm and at
a psa of 7.4 at surgery. My uro at the time wanted to do a biopsy Oct
03. with a psa of 3.x. (I was up around a point from the year before,
but was I was not informed of any underling problems, nor was I educated
about what to notice). I waited 9 months for the biopsy (foolishly) and
it increased to 7.x. I'm wondering about psa velocity of >2 points 1
year prior to RP. Although in my situation it was organ contained with
neg margins, just what was the greatest increase in psa attributed to,
pca or enlargement? Is there any answer? The prognosis may depend on it,
or it may not. So far, so good. Coming into my 18th month in June for
the next psa test. Questions, questions....just psa anxiety I guess.

B.A.

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ron - 03 May 2006 23:10 GMT

Bob...We can take the analysis a step further. So let's say that
(7.4-3.7) = 3.4 ng/ml of PSA came from PCa around the time of surgery.
Strum uses the following Table to calculate the "PSA leak" from the
cancer and then the PCa volume:

Gleason Grade PSA leak
(Weighted) Exact
5.0 0.93
4.5 1.36
4.0 1.99
3.5 2.92
3.0 4.26
2.5 6.23
2.0 9.12
1.5 13.33
1.0 19.49
So if you had a GS = 3+3 after surgical pathology, 4.26 ng/ml of PSA
would be produced by every cc (or gram) of cancerous tissue. Since
your observed leak was 3.4, the formula would suggest that you had
3.4/4.26 = 0.8 cc of tumor. Just redo the math if your average GS was
not 3.0.

Now you can go back to an earlier PSA, assume your GS didn't change and
run two cases, 1) how much the prostate would have to grow to account
for all the PSA change, and case 2) how much the tumor would need to
grow to account for all of the PSA change. The truth should lie
sommewhere between these two case. Just ask another question if I'm
not clear...Hope this helps, Ron

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Bob Anthony - 04 May 2006 16:22 GMT

Thanks Ron:

Got it. Then according to my calculations, my prostate was approximately
47 grams in 2002, whereby in 12/04 it was 56 grams. Hmmmm...a 9 gram
growth spurt from 3/02 to 12/04.

My avg GS = 3.5.
3.4/2.92 = 1.16 cc
Psa 3/02 was 3.1
47 gm x 0.067 = 3.1

Interesting data. Am I correct in these calculations?

B.A.

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ron - 04 May 2006 16:51 GMT

Yep, looks right to me (your "leak should be 3.7, not 3.4, my error up
above). So you had little or no tumor back in '02 and something around
(3.7/2.92=) 1.27 cc at surgery...Ron

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Bob Anthony - 04 May 2006 23:05 GMT

Thanks Ron for prompt and informative replys. Now, who says that pca
grows slowly? I guess compared with other more aggressive cancers, it
does. A 1.27 seems rather fast presuming there was little or no tumor
back in '02. Am I correct in this assessment? Obviously, it is >.5 and
was well worth the effort removing it in any event.

B.A.

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