Doubling Time Question: Would any... - Advanced Prostate...

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Doubling Time Question

mangeycritter profile image
22 Replies

Would any members please comment about how to interpret doubling time data.

Prostatectomy in Jan 2012. Recurrence in Jan 2016 @ 0.2. Current PSA is 5.70

Using all 23 measures since recurrence gives time of 9.09 mos.

Using last 12 months gives time of 8.77 mos.

Using last 9 months give time of 11.2 mos.

Using last 6 months gives time of 16.26 mos.

Using last 3 months gives time of 87.02 mos.

Not currently receiving any treatment, but about to start ADT. How should I interpret the doubling time data?

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pjoshea13 profile image
pjoshea13

If your PSADT is trending upwards, why rush into ADT? -Patrick

mangeycritter profile image
mangeycritter in reply topjoshea13

Thank you pjoshea13. That's exactly what I'm asking myself, but every doc says ADT now., as does the encyclopedic Tall_Allen below.

Pray the adt knocks the pc down and that it keto you undetectable for many years.🙏✌️

mangeycritter profile image
mangeycritter in reply to

Thanks Wimpy-p. If I'm truthful to myself, I'm whimpy with a capital W.

in reply tomangeycritter

My beautiful healthy with named me so . I’m going with the wimpiness.. We get whittled down pretty well with APC and treatments. We will laugh and cry . I don’t want to go out an angry guy . So accepting our lot it a must . We roll with the punches until we can’t no more. Today is hopefully not our day to depart . Give thanks for everything good in life. And throw the rest in the trash heap ..

Tall_Allen profile image
Tall_Allen

You seem to be over-reliant on PSA, and getting them too frequently. You've had metastases identified in non-pelvic lymph nodes (Stage M1a), so ADT is called for.

mangeycritter profile image
mangeycritter in reply toTall_Allen

Thank you Tall_Allen. Wish there were some way to prove a negative, i.e., what progression would happen, and over what time period, absent ADT. I'll be 79 in Sep.

Tall_Allen profile image
Tall_Allen in reply tomangeycritter

That's not "proving a negative," that's exactly what randomized clinical trials do. What you want to know is what will happen to you, and no study in the world will ever be able to tell you that. Most us us assume we won't do better or worse than the average.

We don't have data on Lupron vs no Lupron for metastatic PC for historical and ethical reasons, but we do have data on Zytiga+Lupron vs Lupron alone in men with mHSPC.

StayingOptimistic profile image
StayingOptimistic in reply tomangeycritter

I am 65 and struggling with the same decision but I am leaning now more towards starting ADT but afraid of resistance

GoEZ profile image
GoEZ

I had problems with this concept. I watched every little bump in my PSA and became a pain in the butt for my doctors. My doctor said that your PSA number means very little, It was the change in the number that mattered.

There are a few websites that will calculate your doubling time for you. I use the last 3 upward PSA reading to calculate DTime. I found that at 90 day DTime my Doctors would start getting excited and change my treatment. I have been down to a 42 day turnaround. I have talked to guys with Psa’s in the hundreds but it took them 10 to 15 years to get that high. I would have topped that in a 16 months. I find this number to be more informative about how my cancer is progressing. This is just a small piece of the cancer puzzle but it is a good way to look at your numbers.

Jan 16 to today (51 months), during which 23 samples -> 2.2 months average sampling period.

In mathematics PSADT is the first derivative of PSA. What you are concerned about is the first derivative of PSADT which obviously is the second derivative of PSA.

As a general concept, each time that a data time series is differentiated (to numerically extract its derivative) the data errors get higher by one order of magnitude (x10). Consequently, with the data at hand what you are asking is comparable to trying establishing a PSADT from 2.3 PSA values. Not ideal, but doable. Surely, NOT the way you are trying to do it.

What I would do:

I trust that monthly PSA counts give reasonable accuracy for PSADT.

Accordingly, PSADTs calculated on 10 months basis give comparable accuracy.

How are you going to do that?

Take all 23 samples and separate them into 5 sub-groups spanning 10 months each.

You should have MINIMUM 3 PSA values per sub-group. If needed, adjust the time window to accommodate min 3 samples. For your info, this is called "windowing".

Now, in order to have some smoother transition between the 5 "windows", apart from the first one, you will add the last sample of the previous window to the next one. So, 4 samples will be used twice during further processing, making the total sample count (with overlaps) 23+4=27.

Example: Your first window has 3 samples (#1,#2,#3)

Your second window has 4 samples (#4, #5,#6,#7) but from the overlap gets sample #3 from the first window and totals 5 samples from now on.

Next, you will calculate PSADT for each and every window as previously described with overlaps.

You now have a time series of 5 PSADT values. Graph it in EXCEL with linear and exponential regression functions and see how it goes.

mangeycritter profile image
mangeycritter in reply to

Thank you Justfor for your interest in my question. I am nowhere your level of mathematics/statistics, so don't understand the process. I have grouped the measures per your instructions, resulting in PSADT's of 21.01 (1st grp of 3), 9.59 (1st grp of 5), 6.96 (2nd grp of 5), 9.76, 6.18 and 25.04. Entered in Excel, created line graph, but unable to find lin and expon regression tools.

As an aside, does not the MSK nomogram for PSADT already include these functions?

Thank you again.

in reply tomangeycritter

The easy answer is yes, the MSK nomogram does exactly that. This is why you can use it to derive the 5 sub-group PSADT values. It is more convenient than doing it the EXCEL way. Speaking of which, I fear that there may be some typo with the calculated PSADTs . If the last number i.e. 25.04 is a PSADT value and not the 25th of April (European date format) than you had an unexpected deceleration of your PSADT. Good for you if this is true, but in your initial post you wrote: "Using last 12 months gives time of 8.77 mos."

Also, hope that you used the overlap, although this does not surface from your writings.

The Excel regression functions:

SLOPE(A1:A5;B1:B5)

Array A contains the PSA values and B the time (in days or months) from t=0

INTERCEPT(A1:A5;B1:B5) as above.

These two numbers define a linear equation which, under certain criteria, is the best linear representation of your input:

y = (INTERCEPT) + (SLOPE) x time

Next comes the exponential regression:

It is like the linear one, once you have converted all PSA values with LOG(Ax;2)

The Logarithm Base=2 is used for convenience as it easily spots doubling time.

Any Log Base can be used, like 10 or the base of natural logs, as long as the final values are converted back with exponentiation. In the case of Base=2 this means 2^(estimated value).

One thing that I missed mentioning before is that the time stamp for each calculated PSADT value better be the date of the last PSA test used within each subgroup.

In theory, the mid-time of the subgroup is better, which will introduce some latency, (always present with numerical filtering) but if your sub-groups, including overlaps, span to one year, 6 months of latency will not become a deal breaker.

PS Reading again I fear that you made the following mistake:

You didn't divide the 51 months into 5 10 month periods, but you divided the 23 tests into 1x3 +4x5. If you were very punctual with your tests and had one test every 2.2 months this would have been the same. BUT, if during older years you had one test every 3-6 months and lately you started monthly tests, this can be the cause of the discrepancy (25.04) I mentioned. You have to re-sample your data in time NOT in original samples. If during the latest 10 months you had 10 tests than you shall calculate your PSADT for that period with 10+1 samples NOT 5 or 6.

mangeycritter profile image
mangeycritter

Thank you Nalakrats. Begin Vantas implant this coming Thursday. Not looking forward to it, but hard to breathe while sticking head in the sand. I'm M1a with 2 thoracic nodes under G68 PSMA, but clear under normal scan.

mangeycritter profile image
mangeycritter

Nalakrats,

Would you mind amplifying what you mean by 5-AR's and an Aromatase Inhibitor. Thank you again.

mangeycritter profile image
mangeycritter

Thanks again Nalakrats. I have followed many of your posts, and think I've identified the supplements you use: Pectasol-C, Glutathone reduced, D3, N-acetyl Cysteine, B12, Folic acid, etc. I remember your saying that it would be tough to find a urologist using Vantas, which I certainly found to be the case. Searching FL, GA, SC, and NC, finally found Levine Cancer/Atrium in Charlotte , NC. Going this Thursday. You may have misinterpreted my earlier comment---not worried about the implant, worried about chemical side effects. I recognize you do not give medical advice, but nonetheless, when researching treatment option/side effects, etc, nothing like getting info from the horses's mouth. Many thanks.

mangeycritter profile image
mangeycritter

They tell me I'll be seeing Elizabeth Korede (sp?), nurse practicioner for Dr. James Kearns. I've seen Dr. Daniel George at Duke as my medical oncologist.

mangeycritter profile image
mangeycritter

Hello again Nalakrats,

Once again if you wouldn't mind I'd like your suggestions. Yesterday I had the Vantas implant installed at Levine Cancer Institute on Morehead Medical Dr. in Charlotte by Dr. Kearns' nurse practitioner. I asked her about using CAB by adding casodex but she kind of shifted the discussion to the sequential use of other drugs rather than the concurrent use of an anti-androgen. I also asked if a telemed consult with Dr. Burgess would be possible and she said she would send a note over to his office. This was late yesterday so no response yet.

FYI, MO at MSK said 3 month Lupron, MO at Duke said 1 year Lupron, local Urologist said 1 month Lupron (to test my tolerance),then 6 month plus Zytiga (if able to have insurance pay). I think I understand the Lattitude and Stampede trials strongly favor CAB over monotherapy, but the people I have seen seem to discount that. I find that this variance among the docs makes it difficult for me to assess the best plan.

So---- 2 questions really. Should I expect a "surge" (I've forgotten what surges, PSA or T) with Vantas (the nurse didn't suggest any other drug treatment), and if so, what should I do? Do you have a suggestion as to how I might convince LCI to prescribe casodex? Again, thank you for paying attention to me.

mangeycritter profile image
mangeycritter

Thanks again, N.

mangeycritter profile image
mangeycritter

Hello Nalakrats,

Once again, I would appreciate your input. From above, I had Vantas implant on May 7 at LCI. I met with Dr. Burgess on June 15. I found him to be very informative and interested in my situation. He suggested that for me (brief history: Surgery 2012, BCR 2016. No treatment. Steadily rising PSA to 6.0 in 2020. No genomic results of any import. Only somatic result is SPOP. 2019 G68 PSMA shows 2 thoracic nodes). Dr. Burgess said Vantas + Zytiga better choice for me---if I understood him correctly, this gets to the same endpoint as ADT + anti-androgen, but through a different mechanism. He also mentioned that, although not SOC, if I wanted to "swing for the fences"I might consider radiation since oligometastatic. Said the castration resistance usually in 1 to 2 yrs w/o Zytiga, 3 yrs with. I am confused by this, as I have other reports with longer time to CR. My fear is that CR is one step ahead to hospice. He recommends that first step is CAT scan and bone scan. If no other metastases evident, then can consider radiating the 2 nodes. If others evident, radiation out... He is willing to treat, but wants me to establish relation with a local MO who is willing to work with him as the quarterback (I don't know how likely I can find such an MO, but worth a try). BTW, In our discussion I mentioned that my wife is being treated at MSK for meta bladder by Dr. Rosenberg. He asked if I meant Jonathan Rosenberg, which I did. He also knows by first name Richard Joseph here at Mayo, whom he said is his go-to guy in Jacksonville. My wife had an absolutely horrific experience, which I witnessed, with Joseph, which led me to discover Dr. Rosenberg. Sorry for the digression---just wanted to make the point that Dr. Burgess seems to know many of the players and seems to be aggressive in his treatment approach. If you don't mind, I would very much like your input and suggestions.

Best regards,

mangeycritter

mangeycritter profile image
mangeycritter in reply tomangeycritter

Once again, many thanks Nalakrats. I don't know how I discovered HealthUnlocked, but what a godsend, with many highly-informed posters, esp you, LearnAll, Tall Allen, etc.

In case a poster should ask you for an MO in south FL, I'd like to pass this on:

Jonathan Rosenberg was faculty at Harvard, chief at Dana Farber, now chief at Sidney Kimmel at MSK. He has been treating my wife since 2018, and last summer he suggested to her that she might avoid travel every 3 weeks to NYC over the winter and he would be willing to refer her to Dr. Guancial ("I would send my parents to her") Dr. Guancial was a fellow under Rosenberg at Farber. A while back I replied to a post asking for MO in south FL. Suggested Guancial. Poster started with her in Jan 2020 and reports he is very pleased. Guancial is at FL Cancer Specialists in Sarasota. Her credentials: Harvard med sch, Resident at Mass Gen, Fellow at Dana Farber, trained by Rosenberg. My wife in extremely pleased and confident in Guancial's care, which continues every 3 weeks until July, 2021. Complete remission with pembro. Just sending this along in case it may help someone in the future. I intend to proceed with Dr. Burgess if I can find a willing MO locally.

Many, many thanks.

Mangeycritter

Horse12888 profile image
Horse12888

I don't see here that you're getting radiation on the mets found in the scan. Is the question: ADT on top of that?

Tall-Allen says that ADT is always indicated in the case of distant mets, and I'm sure he's right from a CSS and perhaps an OS survival perspective as well. But given that your PSA has all but stopped growing, I'd be a hard sell, personally.

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