I was kind of curious today about my own PSA doubling time, (PSADT), and what it means about overall survival, (OS). Before today, I mistakenly thought my doubling time was always the same, that it was just a sign of the type of prostate cancer I had, how far it has spread, and my body's immune system response to it. But when I looked at it over the many years that I have had advanced PC, I realize now that it has changed dramatically over time. When I first started to have PSA increase in 2012, I had a PSADT of 1.5 months. later, in 2018, I had a PSADT of 3.5 months. And then in 2019 it rose to 9 months and in 2020 it rose to 15 months.
What that means is that my estimated overall survival rate (OS) became longer than it was years ago. I don't know exactly what the reason for this is, but I suspect it is due to my personal immunity and things I have done with diet, (lycopene) and heat treatment of metastases.
The only time you might calculate doubling time is while you are on vacation from ADT, unless of course you are no longer hormone sensitive, and your PSA is rising in spite of ADT. If you are hormone sensitive, and the cancer cells are prevented from growing by ADT, then the PSA is usually quite stable, and there is no doubling time if there is no change in PSA. But when you are on a vacation from ADT and your PSA is growing, then you can use your PSA test record to evaluate your doubling time. And therefore, an increase in doubling time over the years means you can estimate longer overall survival, while if your doubling time decreases, your estimated survival is shorter.
The researchers found that the men with the shorter PSA doubling times had a shorter time before they developed metastases (shorter metastasis-free survival (MFS)) as well as a shorter overall survival (OS). They also found that the men who had developed metastasis had a three times higher risk of dying than those without metastasis
I'll try to answer this as simply as possible. I went to my records which are online, but I also kept my own records. I listed them on a piece of paper. Online records showed three periods of vacations from Lupron, but in my own records there were four. I can't explain how one period was lost.
In the first period, PSA was 0.4 at the start, and 8,2 seven months later, when Lupron was resumed. Doubling 0.4 four times leads to 6.4, so doubling time was around 7months/4.5times=1.55 months.
In the second period, PSA was 0.8 at the start, and 6.4 ten months later, when Lupron was resumed. Doubling 0.8 three times leads to 6,4, so doubling time was around 10 months/3 times = 3.3.
In the third period, PSA was 0.1 at the start, and 34.3 thirty-eight months later. Doubling 0,1 eight times leads to 25.6, so doubling time was 38 months/8.5 times =4.5 months,
During the end of that last period, PSA rose from 16.9 to 34.3, roughly double, in 17 months, which makes doubling time 17 months, when Lupron was resumed.
Since then I have had PSA <0.06 for the past four years, on Lupron quarterly.
Thank you. The reason I asked about the PSA values you used is that at very low amounts there is some debate whether they can really be used to have any diagnostic value in computing PSA doubling time. You also need to use at least three points to establish a trend.
You may want to google search “PSA doubling time calculator”. There is one from a huge cancer center in NYC that people use. Do not have it off hand.
You are welcome. Read your bio. We are very similar in diagnosis. I had 25 sessions of IMRT. However I also had my entire pelvic area radiated as a precaution to unseen spores. I had 6 months of ADT.
I am almost 20 months out of radiation and off ADT about 15 months ago. Last PSA was 0.09. My T is back to normal along time ago at around 700.
I have noticed small changes in PSA in the +- 0.02 range. Nothing to worry about.
I am still on ADT - will be on it thru 2025. My Doc orders regular PSA tests as opposed to the ultrasensitive PSA test. So far, so good re., PSA levels (at zero). Will cross the stop of the ADT bridge when that time comes.
Couple of things I would have done differently, in retrospect: A) Would have started on Orgovyx before getting the initial biopsy of the prostate to determine presence of cancer cells - this might have eliminated any chance of leakage of cancerous cells due to the biopsy; 2) Would have gone on ADT, even while on Active Surveillance - ie., before deterioration to the stage where Radiation (I did not want proctectomy) became necessary. Well, what is past is past. Praying for more, and rapid advances in cancer research! Meanwhile, your continued success gives us all hope!
Good luck to you moving forward. God knows what the future holds. Think positive.
We had 16 inches of new snow so I am going to do a half day of skiing.
Tomorrow the dogs and I will spend a couple of hours snow shoeing in the forest. I put boots on them to protect their pads. All of us sleep like babies after that.
PSADT is difficult to evaluate. Do I use 3 data points? A years worth? Everybody does not use the same number of PSA values. Using my own, I can calculate very different PSADT by how I pick the data.
I believe that you have an additional problem. Lupron wears off very slowly. So your starting PSA values are very probably repressed due to slow testosterone levels. Personally I would not use any PSA numbers that are at a time of "incomplete" T recovery.
A further complication: The best formula for calculating PSADT is to find the least squares line to fit the data. The online calculator Mgtd mentioned does that. I played with the calculator adding or taking out values to see how it affected my PSADT. I was surprised at some of the results. And I'm a science/math guy!
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Modified Citrus Pectin - reply from Dr Eliaz
First PSA Three Months After Starting ADT Vacation
