sudden stop in PSA decline

[lokibear0803]

I‘ve been doing IADT, and started relugolix in December 2022, with PSA 7.48, and each monthly PSA decline since then was significant and reassuring. Here’s the history:

December 7.48

January 0.94

February 0.49

March 0.24

April 0.09

May 0.09

So suddenly the May PSA remained the same as April, after impressive drops in previous month-to-month measurements.

Here’s my thinking so far:

— the early months from January-April suggest I’m still solidly hormone-sensitive

— if the zero-change in May indicates castrate resistance, I’d be surprised it showed up so suddenly

…is this in fact how CR begins to appear?

— my MO has suggested this may be my new normal for nadir (previously it’s been 0.02-0.04)

…if so, is this an indication that CR is starting to show up?

— I’d done a long bike ride three days before blood draw, long enough to make my butt very sore

…could this have been a factor?

— I’d not yet taken my daily relugolix that morning before the PSA draw

…could this have been a factor?

— I have seen variation in my PSA at low levels - sometimes it even increases from month to month

…so this could be simple coincidence of timing in measuring normal PSA up-and-down

My inclination is to buy into the last idea, and regard this as simple variation that got measured on its way down from an upward bump, coincidentally measured at the exact same level as the previous month. As I mentioned, I’ve even seen changes from 0.02 to 0.05 in my PSA, so this apparent “plateau” should come as no surprise.

Your thoughts are welcome, and I thank you in advance.

[Justfor_]

Of all the stated causes the bike ride makes the most sense to me. I understand that you still have your prostate, right? With 2.5-3.5 days of PSA half-life lets do a rough estimate: You would have anticipated seeing a count of 0.05-0.06. Lets split it in two equal parts, half of it originating from the prostate, the remaining from lesions outside it. You got 0.09, ie. the prostate contribution doubled from 0.03 to 0.06 after 3 days of decay. So, just after the bike ride it quadrupled from anticipated. Doesn't sound far fetched to me. But, these are pure theoretical thoughts. If you want to know for sure, just repeat the test.

[lokibear0803 in reply to Justfor_]

Thanks Justfor.

I’ve done that same calculation in general around bike rides, and in principle I agree with your approach to it.

But then I read things on this forum and elsewhere that any effect is negligible after 48 hours. It makes me wonder if there are more variables than just the PSA half-life.

But you’re right, I can simply do a retest. However, when I was at one point doing weeklies, the variation was surprising — there was noticeable up and down, so it didn’t seem a reliable predictor. I’ve concluded that monthly at a minimum is the most useful. Sigh.

[Justfor_ in reply to lokibear0803]

There are two distinct cases that you should discriminate between:

1) Cycling while NOT being under ADT. Actively expressing PSA cells are equal to all existing. In such a case quadrupling would be far too much because all cancerous cells are actively expressing PSA and for this to happen each and every one should gears up to 4x.

2) Cycling while being under ADT. A limited cell population is actively expressing PSA, but beside them there is a greater number in dormant state, because the energy supply is limited. While cycling blood circulation into the prostate gets elevated, permitting some of the latter waking up. In such a case 4x can be feasible.

I have noticed this during my Bicalutamide maneuvers. My PSADT prior to starting the drug was much longer than that after sub-critical dosage. It is the compressed spring - suddenly released free, kick action.

[lokibear0803 in reply to Justfor_]

Thank you, Justfor, for taking some time on this.

[cujoe]

Locibear - The following is excerpted from an article at LEF. It is a reasonable guide to getting consistency in your lab results. I make a point to use the same walk-in labs for labs not done at my cancer center or PCP. When possible, I also try to get the blood draws done around the same time. In my case, that is before 10:30 AM and always in a well-hydrated, fasted state:

* * *

The PSA level in the blood, like many lab tests, has a rhythm based on the time of the day i.e., a diurnal rhythm. Therefore, obtain your PSA blood tests in either the morning or the afternoon, but not both. And, the laboratory testing method (assay) and even the lab itself doing the PSA can lead to variability in results, so make sure the same methodology is used e.g. Hybritech, Tosoh, DPC, etc, and return to the same lab facility for all your PSA testing. Following these recommendations will decrease aberrant PSA test results. You may hear your local physician say that all of the above is controversial, but you have nothing to lose and possibly something to gain by avoiding these possibly confounding issues.

* * *

If also testing for Testosterone, time of day and previous night's sleep can have a significant effect, with morning labs being significantly higher than those done in late afternoon. I have over 30 T labs done since 2013 and without exception, the afternoon labs always have fallen significantly below the trend line of the morning labs, often by over 200 ng/dL. These effects obviously become manifest on non-castrate T-levels, so I'm not sure there is enough impact on castrate T-levels for concern. As for sleep, sleep researcher Mathew Walker has noted that 4-5 hours of sleep (vs. 7-9) can effectively age your testosterone production by the equivalent of being 10 years older. Same applicability to normal vs castrate T-level as with time of day for blood draws should be noted.

With more labs, trends are both defined (3 sequentially in same direction = trend) and confirmed (4th higher or lower than the last point on the trend = confirmation - or not.) Easy to overthink minor variations. When I have reason to question direction, I pay up for a walk-in lab for clarification and peace of mind.

Trying to create consistent conditions for blood draws obviously helps assure reliable results, but labs equipment can sometimes be out of calibration and poor blood draws and handing can also potentially affect results. Over time such "noise" tends to disappear.

Good Luck! Ciao - K9

[lokibear0803]

Many thanks, Cujoe!