Good Chris, I always enjoy a psa discussion. I haven't clicked on your link due to the warnings but some time ago I posted a link from Practise Update with an analysis saying psa density rose with Gleason.
I also did some calcs and decided the known size of my tumour pre-Op, 13mm dia, Gleason 4+4 seemed about right with psa =9.9 using perhaps 'convenient' assumptions.
More interestingly from that I did some calcs to work out how large my current tumour as of May23 might be with a psa of 0.09. The article and my calcs are below although off hand I no longer fully understand the working.
Per cc
My tumour was said to be 13mm diameter pre-op.
V=(4/3)πr3
Pre operation my psa was 9.9 and gleason 4+4 and 13mm diameter.
Gleason 4 = 0.7 times 9,2 would be psa 6.4. Plus what might be assumed a normal psa of around 3. Means my total calculated psa = 9.7 using the stated assumptions. The actual value was 9.9.
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Current lesion size(May 23). Using the above calcs with my psa at May23 which is 0.09
I can't be certain of the Gleason. But if still Gleason 4 the lesion could be 0.09/0.7=0.1286mm
Or if Gleason 3 could be 0.09/0.11=0.8182mm i.e. bigger.
If benign could be 0.09/0.05=1.8mm i.e. bigger.
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The article text:
OBJECTIVE
To evaluate how blood levels of prostate-specific antigen (PSA) relate to prostate volume of benign tissue, Gleason pattern 3 (GP3) and Gleason pattern 4 (GP4) cancer.
METHODS
The cohort included 2209 consecutive men undergoing radical prostatectomy at 2 academic institutions with pT2N0, Grade Group 1-4 prostate cancer and an undetectable postoperative PSA. Volume of benign, GP3, and GP4 were estimated. The primary analysis evaluated the association between PSA and volume of each type of tissue using multivariable linear regression. R2, a measure of explained variation, was calculated using a multivariable model.
RESULTS
Estimated contribution to PSA was 0.04/0.06 ng/mL/cc for benign, 0.08/0.14 ng/mL/cc for GP3, and 0.62/0.80 ng/ml/cc for GP4 for the 2 independent cohorts, respectively. GP4 was associated with 6 to 8-fold more PSA per cc compared to GP3 and 15-fold higher compared to benign tissue. We did not observe a difference between PSA per cc for GP3 vs. benign tissue (P = 0.2). R2 decreased only slightly when removing age (0.006/0.018), volume of benign tissue (0.051/0.054) or GP3 (0.014/0.023) from the model. When GP4 was removed, R2 decreased 0.051/0.310. PSA density (PSA divided by prostate volume) was associated with volume of GP4 but not GP3, after adjustment for benign volume.
CONCLUSION
Gleason pattern 4 cancer contributes considerably more to PSA and PSA density per unit volume compared to GP3 and benign tissue. Contributions from GP3 and benign are similar. Further research should examine the utility of determining clinical management recommendations by absolute volume of GP4 rather than the ratio of GP3 to GP4.
From <https://www.practiceupdate.com/content/contribution-of-gleason-pattern-4-prostate-tissue-to-blood-psa-levels/146431/55/3/1>