In the short time I've been here I've noticed a lot questions and concerns over what I see as very minute differences in PSA test results that are 2 or 3 decimal places of precision. I get that everybody wants to see their test results in a straight line downwards and when they don't anxiety understandably sets in but given the nature of the PSA test with acceptable variances and outside influences that can affect the results I'm wondering if I should be concerned about such small variances. My PSA test results only come out with 1 decimal place, e.g. 0.1 or 0.2, nothing in between. Should I be pushing for results that have more detail?
Thanks
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fireandice123
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No, the only meaningful use of 2 or 3 digit ultra-sensitive PSA test is the first year after a prostatectomy of high risk PC. For others, it only creates anxiety.
Your confusion probably arises because those men are in a different situation from you. Ultrasensitive PSA only makes sense for men with localized PCa who have had a prostatectomy. They are trying to decide when salvage radiation is needed. You need only one decimal point for the kinds of decisions you may have to make.
Not necessarily. There is an unbreakable law of information theory that says: Doubling the sampling rate equates to halving the quantization error. Without it, no electronic device employing signal processing, regarded as commonplace today, would existed. In practice, if you are taking a 0.1 resolution PSA test every 6 months and you upgrade to quarterly, then the "effective" resolution will come down to 0.05. It will take some very elementary number crunching to achieve this though.
I'm on monthly blood tests since my /Xtandi history is about where many have experienced failure. My PSA is starting to climb, but only up to where it was 2 1/2 years ago at this pt and not over 0.2 yet.. Worried? NO-- concerned--Somewhat. I've had so many slight ups and down in the last year that I have come to expect them.
My urologist (perhaps ex-urologist, I'm interviewing a new one in a week) has always prescribed ultra-sensitive PSA tests. Quest Labs ignores his request since I still have a prostate (did IG/IMRT). My radiologist and oncologist are perfectly happy with a "standard" (less than 0.1) PSA test. So am I.
If you had a RP then I believe from my reading, there might be some justification for the ultra-sensitive PSA test in deciding on followup radiation. If you still have a prostate - it makes no sense. Especially with any sort of primary radiation treatment where it may take 6 months or longer after treatment stops for the effects of the radiation on the cancer to conclude.
My results 2 months after treatment were 0.l (whatever unit), since that time (2 years later now) quarterly PSA reads have always been less than 0.1, which is fine with me.
PSA is not always an accurate indicator. We are all different.Your normal is different from mine. Doubling time is more important. Other tests may collectively be more important. If tracking Mets then ALP must be considered. Rely on your MO, to order and evaluate ALL your tests together to judge your unique treatment path. Educate yourself about all your tests but we are ill equiped to judge them together.
Snuffy Myers always recommended an ultra sensitive PSA test. That’s what I’ve been using for the past 6 years. Snuffy’s goal was to reach a “long term durable remission” and using an US PSA test was one way to measure that. I’ve had an undetectable PSA for over 6 years until recently when it’s become detectable again at very low levels, the latest is .022. I prefer the US test because it gave me a heads up to my cancer becoming castrate resistant and allows me to plan the next course of action with my MO’s once it reaches a certain level. It is not a source of anxiety for me, I’d rather get the early alert so I can plan activities, make financial decisions etc. So I disagree with those who say it’s only for localized PCA, I’ll stick with Snuffy’s protocol.
I generally agree that ultra sensitive PSA produces more anxiety than actual useful information, but my case may be an exception. Not all cancers put out a lot of PSA. I have a mix of intraductal carcinoma (puts out less PSA) and neuroendocrine (puts out zero PSA). Last summer, on Lupron and Abiraterone my PSA went from <0.01, to 0.02, then 0.03. My neuroendocrine was returning to my liver, so on the advice of Dr. Beltran we stopped abiraterone and started cabazitaxel chemo. The CT scan also noted progression in one rib. Initially my PSA skyrocketed to 0.16, then started dropping after starting cabazitaxel. After three cycles my PSA is back to 0.03, and the CT scan showed the rib was stable and the cancer in my liver had exploded all over the place.
I've since been switched to folfiri (a decades old colon cancer chemo), my liver is improving, and my rib and PSA are both stable at 0.03 (Lupron only, with an intact, never treated prostate that currently has no obvious signs of having any prostate cancer in it).
I had previously had progression at <0.01 PSA, but that doesn't count because that's when I was diagnosed with the neuroendocrine cancer. But based on the above evidence and my rib responding to cabazitaxel, the slow increase form <0.01 to 0.03 was indicative of cancer progressing in my rib.
A few years back, I had colon cancer. I was given the choice of folfiri (in my case 5-Fluorouracil) through a port and Oxaliplatin IV every 3 weeks, or Oral Xeloda (Capecitabine) for 2 weeks out of the 3 week cycle and the Oxaliplatin IV every 3 weeks. Went through 2 cycles then was determined to be allergic to Xeloda, so treatment was stopped. 5% of the population are allergic to Xeloda, but test is so expensive, the test is to put you on it. You might ask your doctor about Xeloda, since it is same as Folfiri, but with the convenience of being oral. I was msi-High for the colon cancer, and the 2 cycles seemed to have been successful so far. (I am msi-Low for prostate cancer, so no advantages there.)
If you're on oxaliplatin that sounds more like folfox to me. The "iri" in folfiri refers to irinotecan, also known as "I run to the can" for its most prominent side effect. My cycle is only 2 weeks, and includes a 46 hour infusion of 5-FU. After that I'm done with chemo drugs for the next 11 days. This seems to be working very well, I'm reluctant to mess with success.
I would ask for 2 significant figures. There’s a huge difference between 0.1 and 0.2. Ideally you want to know what the doubling time is. If you only have 1 decimal place then 0.1 to 0.2 could mean. 0.14 to 0.16, which is a tiny increase. Or it could mean 0.06 to 0.24 which is a 4 fold increase. Hugely different interpretations of those results, especially if they are three months apart.
In Australia I’m pretty sure you can’t get results with less than 2 decimal places (when it’s less than 1) so I’m not sure why they are even still doing that in the USA
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