PSA Doubling Time

[MGBman]

I suspect there are many ways to calculate PSA ‘doubling time’ but I seem to have a bit of a head scratcher. Have had a prostatectomy, radiation, Zolodex and finished 8 months of degarelix end of Aug. By 25 Oct my PSA was 0.44. On 15 Dec it was 1.99 and 18 days later on 03 Jan it was 2.84. By my Oncologist’s calculation my doubling time is 8 months. Now I know math was not my strong subject in school but a rise from 0.44 to 2.84 in approx 70 days would seem to me to be a tad bit high and more than ‘doubling’ in a few weeks let alone 8 months. Unfortunately, I forgot to ask my Doc how he arrived at 8 months. …my bad. I have another PSA on 03 Feb and fully expect that it will be 4-5-6ish. Doctors are very smart and much better at math than yours truly so if someone has any ideas how he arrived at 8 months I would love to know. I will ask him what formula he uses but in the meantime if anyone has some thoughts that would be interesting..

[Poowater]

My psa was doubling every 2 weeks. Usually, psa should double every 12 months. Have had 2 infusions Pluvicto, now psa down by 59% in month.

[NEHOG in reply to Poowater]

Pluvicto appears to need at least three infusions before it starts to have much of an effect on PSA--According to the oncologist I was with the other day. However they did say that once past the third infusion the results were impressive in most cases.

[Poowater in reply to NEHOG]

Thanks for this info.

[Hidden]

I use this.

mskcc.org/nomograms/prostat...

[MGBman in reply to Hidden]

Thank you for the link. I put in my numbers and the response was somewhere in the neighborhood of 4-5 weeks not 8 months.

[Justfor_]

He probably dropped off the 0.44 sample as not being certain of the degree the ADT had washed out by that time. Probably, calculated some DT taking into account only the two later samples. A very debatable approach. I wouldn't give any credit to any DT calculation based on less than 5-6 monotonously rising samples.

[MGBman in reply to Justfor_]

Thank you. While nine degarelix injections drove down my PSA down to 0.29 in Aug, it seems to have had no lasting impact as indicated by my Oct PSA of 0.44. I thought it was instructive that Zolodex (2015-2017) drove my PSA down to 0.01. I wonder if no lasting impact is normal for degarelix or was I a bit of an anomaly?

[MateoBeach]

Well I agree that based on those values your PSADT is ominously short indicating very rapid aggressive growth at present. More in the neighborhood of two months, but you can use one of the online calculators as others have linked.

Regardless, it implies that you need to modify or intensify or add to current treatments to get it under control. Need to review your whole history, current treatment and scans.

[MateoBeach]

your profile shows a single lesion on PSMA and MRI in area of seminal vesicle. And one surgeon said he could go respect it. I would think yes. Alternative would be SBRT. Are you on an advanced AR drug added to your ADT?

[Tall_Allen]

Here's a doubling time calculator:

mskcc.org/nomograms/prostat...

[MGBman in reply to Tall_Allen]

Thank you Tall Allen. I ran my last four PSA results - nadir in Aug (0.29) to - 03 Jan (2.84) and the doubling time turns out be 1.3 months. I wonder if there is a 'technical issue'. My PSA is recorded as ug/L (British Columbia) whereas the nomogram measures in ng/mL/mo. Notwithstanding that difference, my simple logic? math? tells me that my PSA is not taking eight months to double. Anyway, I will have to discuss this with my Oncologist on 13 Feb

[Tall_Allen in reply to MGBman]

Those metrics are the same -- μg/l=10-6g/l=ng/ml=10-9g/10-3l

[MGBman in reply to Tall_Allen]

Thanks...my chemistry has long since faded from my tiny brain

[RMontana]

This is a way you can affect the doubling time. I have taken these supplements now for 3 years; who knows. But this is double blind study tested. TNX

healthunlocked.com/active-s...

[maggiedrum]

The doubling time my MO calculated two months ago was dramatically different than the I calculated using one of the published nomograms that I found. He did not tell me at the appointment, which was shorter than usual because an MD/Resident was going through several cancer clinics for her Fellowship training, and I followed up to get an answer as to why he said that I needed a new bone and CT scan on an urgent basis. He did not mention the reason for "urgent" at the visit and I was a little freaked out.

I used the portal to ask the question and I stated that I had calculated (via monogram) a doubling of 8 months. This is still a bit high and troubling. He said in his reply that my doubling time was 5.2 months. I tried several different models to get that number and I could not. I didn't pursue the discrepancy but I will in the future.

[TomMaloney]

There is a formula for PSA doubling time. Apparently you are not a mathematician, so I will try to walk you through it.

DTD=(T1-T0) * ln|2| / ln|PSA1/PSA0|

DTD = Doubling Time in Days

T0 is the first or old PSA

T1 is the second or new PSA

So (T1-T0) is the number of days between PSA measurements

The * means to multiply by ln|2| which is 0.69315

The fuzzy part is to divide the new PSA by the old and then take the natural log

So here is the good news:

Here is a sample of doubling time calculated

Date PSA doubling time

Date0 10-22-22 0.54 232 days

Date1 01-17-23 0.70

If you replace the 4 bolded numbers with yours,

I will calculate your doubling time and post it here.

If anyone emails [e-mail] with both dates and both PSAs,

I will calculate the doubling time in days and return.

Just title the message doubling time.

Thanks,

Tom Maloney

For all cancer patients and caregivers,

God Bless Us Everyone

[MGBman in reply to TomMaloney]

Hello Tom

Interesting calculation. My four post Degarelix PSAs are:

23 Aug 2022 - 0.29

25 Oct 2022 - 0.44

15 Dec 2022 - 1.99

03 Jan 2023 - 2.84

[TomMaloney in reply to MGBman]

Holy crap,

The doubling times are totally frightening.

The Degarelix looks like it is not working.

Among the 4 dates and PSAs there will be 6 combinations,

pairing each date with all the others

........Date ......PSA doubling time

Date0 8-23-22 0.29 105

Date1 10-25-22 0.44

........Date ......PSA doubling time

Date0 8-23-22 0.29 41

Date1 12-15-22 1.99

........Date ......PSA doubling time

Date0 8-23-22 0.29 40

Date1 01-03-23 2.84

........Date ......PSA doubling time

Date0 10-25-22 0.44 23

Date1 12-15-22 1.99

........Date ......PSA doubling time

Date0 10-25-22 0.44 26

Date1 01-03-23 2.84

........Date ......PSA doubling time

Date0 12-15-22 1.99 37

Date1 01-03-23 2.84

Each of these doubling times is in days.

I consider this an emergency.

I go to Dana-Farber, can you find a top-notch center in your area?

I'm serious, I am terrified for you.

Get the best help you can .

Tom

[MGBman in reply to TomMaloney]

Hi Tom

Thank you for your response. Not sure that I’m completely effed but suspect that I will return to ADT and possibly ADT (+) in the very near future. As I live in Canada we may not be on the cutting edge so to speak but you gotta go with the flow unless one has the resources to jet off to more distant locations in the US, Europe or Aussieland. As an old soldier, you gotta soldier on.

[TomMaloney in reply to MGBman]

All the pharmaceutical companies have a compassionate use plan. Your doctor contacts them for you.Unlikely that you will be turned down.

[Horse12888]

Given that your T is recovering and your PSA is rising as a result, PSADT is meaningless.

[MGBman in reply to Horse12888]

Hello Horse12888. Could you please clarify ‘PSADT is meaningless’.

[TomMaloney in reply to Horse12888]

I totally disagree

[Horse12888 in reply to Horse12888]

PSA doubling time is the length of time it takes PSA to double. But while T is artificially low (on or immediately after ADT), it's impossible to measure PSADT accurately. Granted, if PSA is rising quickly even when T is depressed, that's a real problem.

[MGBman in reply to Horse12888]

Speaking of T, it was noticed that my T started to rise slowly while I was still on Degarelix. It went from a nadir of 0.6 and three injections later it was 1.2. Two months after my last injection my T was 2.4 (25 Oct) 8.5 (15 Dec) and 11.8 (03 Jan). So both my PSA and T seemed to be in ‘lockstep‘. It is interesting to note that the Zolodex I was on in 2015-2017, dropped my PSA to a nadir of 0.01, which was maintained for 10 months after my last Z injection. Degarelix’s nadir was 0.29 and there was essentially no lasting impact after my last D injection. Z and D have different modes of action so maybe that would account for the differences. Anyway, I give my vote to Zolodex